Come L'evoluzione Tecnologica Può Mitigare L'effetto Del Peso Dei Materiali, Degli Equipaggiamenti E Dell'armamento Del Soldato Nell'ambito Delle Operazioni Appiedate

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Centro Militare di Studi Strategici

Rapporto di Ricerca 2014 - STEPI AH-T- 06

Come l'evoluzione tecnologica può mitigare l'effetto del peso dei materiali, degli equipaggiamenti e dell'armamento del soldato nell'ambito delle operazioni appiedate.

Aniello RICCIO, Ph.D. Andrea SELLITTO, Ph.D.

data di chiusura della ricerca: Ottobre 2014

Index

INDEX 1

LIST OF ACRONYMS 3

SOMMARIO 5

INTRODUCTION 6

ANALITYCAL SECTION

1. INTRODUCTION TO THE EVOLUTION OF THE SOLDIER’S LOAD 8

1.1. PRE-MUSKET ERA (700 BCE – 1651 CE) 8 1.2. MUSKETEERS (1651 – 1865 CE) 16 1.3. WORLD WARS (1914 – 1946 CE) 22 1.4. MODERN ERA (1950 CE – PRESENT) 31 1.5. CONCLUSIONS 41

2. MATERIALS 44

2.1. HISTORICAL BACKGROUND 44 2.2. STATE OF THE ART 54 2.3. FUTURE DEVELOPMENT 58 2.3.1. SHEAR-THICKENING FLUID 58 2.3.2. MAGNETORHEOLOGICAL FLUID 61 2.3.3. CARBON NANOTUBES 63 2.3.4. SPIDER-SILK 67

3. UNMANNED GROUND VEHICLES 69

3.1. HISTORICAL BACKGROUND 69 3.2. STATE OF THE ART AND FUTURE DEVELOPMENT 76 3.2.1. FRONTLINE ROBOTICS TELEOPERATED UGV 77 3.2.2. BATTLEFIELD EXTRACTION-ASSIST ROBOT 78 3.2.3. MULTI-MISSION UNMANNED GROUND VEHICLE 81 3.2.4. TERRAMAX 84

3.2.5. LEGGED SQUAD SUPPORT SYSTEM 85

4. POWERED EXOSKELETON 88

4.1. HISTORICAL BACKGROUND 88 4.2. STATE OF THE ART AND FUTURE DEVELOPMENT 99 4.2.1. XOS 99 4.2.2. HUMAN UNIVERSAL LOAD CARRIER 104 4.2.3. HYBRID ASSISTIVE LIMB 111 4.2.4. REWALK 114 4.2.5. TACTICAL ASSAULT LIGHT OPERATOR SUIT 116

5. CONCLUSIONS 119

SPECIALIZED SECTION

6. MATERIALS 121

6.1. PERFORMANCE STANDARDS 121 6.2. BACKING MATERIALS 123

7. UNMANNED GROUND VEHICLES 125

7.1. FRONTLINE ROBOTICS TELEOPERATED UGV 125 7.2. BATTLEFIELD EXTRACTION-ASSIST ROBOT 127 7.3. MULTI-MISSION UNMANNED GROUND VEHICLE 128 7.4. TERRAMAX 129 7.5. LEGGED SQUAD SUPPORT SYSTEM 130

8. POWERED EXOSKELETON 131

8.1. XOS 2 131 8.2. HUMAN UNIVERSAL LOAD CARRIER 132 8.3. HYBRID ASSISTIVE LIMB 133 8.3.1. LOWER LIMB 133 8.3.2. SINGLE JOINT 134 8.4. REWALK 135 8.5. TACTICAL ASSAULT LIGHT OPERATOR SUIT 136

REFERENCE 137

List of Acronyms

AP Armor-Piercing BAP Body Armor, Powered BCE Before Common Era BEAR Battlefield Extraction-Assist Robot BES Bio-Electric Signals BLEEX Berkeley Lower Extremity EXoskeleton CBRNe Chemical, Biological, Radiological, Nuclear, and explosive CCF Chinese Communist Forces CE Common Era CNT Carbon NanoTube CPVF Chinese People’s Volunteers Force CVD Chemical Vapor Deposition DARPA Defense Advanced Research Projects Agency DARPA-AI Defense Advanced Research Projects Agency for Artificial Intelligence DBB Dynamic Balance Behavior EAP ElectroActive Polymers eLEGS exoskeleton Lower Extremity Gait System EOD Explosive Ordnance Disposal ESAPI Enhanched Small Arms Protective Inserts FMJ Full Metal Jacketed FMJ FN Full Metal Jacketed Flat Nose FMJ RN Full Metal Jacketed Round Nose HAL Hybrid Assistive Limb HOSDB UK Home Office Scientific Development Branch HULC Human Universal Load Carrier IED Improvised Explosive Device IOTV Improved Outer Tactical Vest LR LRN Long Rifle Lead Round Nose LS3 Legged Squad Support System MR MagnetoRheological MTVR Medium Tactical Vehicle Replacement MULE Multifunction Utility/Logistics Equipment vehicle MWCNT Multi-Walled Carbon NanoTubes 3

NIJ National Institute of Justice NKPA North Korean People’s Army PASGT Personnel Armor System for Ground Troops PBO poly(P-phenylene-2,6-BenzobisOxazole) – Zylon PMC Precious Metal Clay PSDB Police Scientific Development Branch RAR Royal Australian Regiment RDECom U.S. Army Research, Development and Engineering Command RISS Robotic Infantry Support System RoK Republic of Korea S-MET Squad Multipurpose Equipment Transport SJHP Semi Jacketed Hollow Point STF Shear-Thickening Fluid STRIPS STanford Research Institute Problem Solver SWCNT Single Walled Carbon NanoTube TA Control Tank TALOS Tactical Assault Light Operator Suit TT TeleTank TUGV Frontline Robotics Teleoperated UGV UGV Unmanned Ground Vehicle UHMWPE Ultra-High-Molecular-Weight PolyEthylene VBIED Vehicle Borne IED

Sommario

Uno dei requisiti di un soldato è stato e sarà quello di trasportare armi, munizioni e viveri: inoltre, la diversità e la complessità delle operazioni militari spesso richiedono al soldato di trasportare uno specifico equipaggiamento per la missione e di muoversi, a piedi, attraverso varie tipologie di terreno per lunghi periodi in condizioni di tempo molto differenti. Mentre l’equipaggiamento è spesso cruciale per il successo della missione e per la sopravvivenza del soldato, il suo peso, se in eccesso, può avere effetti negativi. Lo scopo di questo lavoro è quello di descrivere in che modo è possibile mitigare il peso dei materiali, degli equipaggiamenti e dell’armamento del soldato nell’ambito delle operazioni appiedate ed è stato diviso in due sezioni: nel primo capitolo della prima sezione, quella analitica, è stata effettuata una panoramica del carico trasportato dai soldati nel corso della storia. Particolare interessante è che, mentre il carico è stato soggetto a leggere fluttuazioni nel corso dei tempi, la sua percentuale rispetto al peso medio del soldato non ha subito grosse variazioni escludendo particolari eccezioni, questo soprattutto perché spesso ad una riduzione del peso dell’equipaggiamento non è corrisposto una diminuzione del carico, ma un aumento dell’equipaggiamento trasportato (per esempio più munizioni e più acqua). I capitoli successivi vertono sui modi specifici in cui è possibile mitigare l’effetto del carico, in particolare sui materiali, sugli UGV (Unmanned Ground Vehicle – veicoli senza pilota) e sugli esoscheletri. Mentre per i materiali è stato possibile fare una netta distinzione tra ciò che è allo stato dell’arte e quelli che sono gli sviluppi futuri, tale distinzione non è stata fatta per quel che riguarda UGV ed esoscheletri: per queste ultime due categorie, infatti, il confine tra lo stato dell’arte e gli sviluppi futuri è talmente labile da non riuscirne a fare una netta distinzione, in quanto molte di tali tecnologie sono attualmente in fase di sperimentazione e di sviluppo. A valle della sezione analitica è stata presentata una sezione specialistica di supporto, in cui sono state inserite le specifiche della tecnologia esposta nella sezione analitica.

Introduction

Since ancient times, there has always been a complex relationship between the loads carried by soldiers and the requirements of their mission. One of the requirements of a soldiers is, was and will be to carry arms, ammunition, clothing and sustenance, that is the basis for their survival. In addition, the diversity and complexity of military operations often requires the soldier to carry mission-specific equipment and move, on foot, through various terrains for long and continuous periods in very different weather conditions. While the equipment is often crucial for mission success and survival, its weight, when in excess, has led to combat deaths. The purpose of this work is to describe how to mitigate the effects of the load carried by soldiers by means of improvements in materials, and by adopting UGVs or exoskeletons. The work has been divided into a first analytical section and a specialized one:  The analytical section is structured in the following way: o The first chapter debates about the evolution of the soldier’s load, from ancient times to modern era; o The second chapter is focused on the materials adopted by soldiers’ equipment; o The third chapter is focused on UGVs; o The fourth chapter debates about the exoskeletons.  In the specialized support section, the specifications of the technology described into the analytical section are reported.

ANALITYCAL SECTION

1. Introduction to The Evolution of the Soldier’s Load

Before starting the review of the evolution of soldiers’ load, several considerations have to be taken into account: first of all, all the loads described in this chapter are the estimated dry loads and may change according to the environment. As a matter of facts, the 3.2 kilogram coat adopted by the British Army during the Great War could absorb up to an additional 9 kilograms of water [1]. British soldiers, who would start a march with 27.5 kilograms, could well finish with loads in excess of 43.5 kilograms taking into account the effects of water saturation and mud; the American overcoat in the World War II would likewise increase in weight by around 3.6 kilograms. In most cases the loads carried by soldiers described herein are based on an average; this may dilute the true appreciation of loads carried by individual soldiers, most notably those who had specific roles within their unit: a machine gunner or signal operator, for example, would usually carry a load noticeably heavier than a rifleman.

1.1. Pre-Musket Era (700 BCE – 1651 CE) The first iron army ever created was the Assyrian one in the seventh century BCE, during the reign of Sargon II [2]. The production and storage of iron weapons and other metal materials of war became a central feature of the army’s logistical base: a single room in Sargon’s palace at Dur-Sharrukin, also known as Fort Sargon, contained 200 tons of iron weapons, helmets and body armor. The Assyrian soldier was equipped with iron scale armor, helmet, iron shinned boots, shield, sword and spear: equipped in such a way, the Assyrian spearman was thought to bear a load of between 27.5 and 36.5 kilograms. Considering a mean weight of an Assyrian equal to 65 kg, means a carried load between 42 and 56 per cent of body weight.

Figure 1.1: Assyrian soldier fully equipped.

A century later, the Greek infantry soldier, the Hoplite, was thought to carry a load of between 22.5 and 32 kilograms when dressed in a complete panoply of breastplate, greaves, helmet, shield, spear and sword. For the Hoplites, who themselves may not have weighed more than 68 kilograms, this equated to a load of between 33 and 47 per cent of their body weight. The key strength of the Hoplite equipment was the heavy Hoplite shield that alone weight between 6 and 8 kilograms; however, this was often discarded when fleeing the battlefield, action that lead to the saying of Spartan mothers: “Come back with your shield or upon it”. Probably the Hoplites may not have carried this complete load during the march, because each soldier had one or more slaves, called skeuphoroi or baggage carriers, who carried the soldier’s provisions, bedding and personal kit and, when no threat was imminent, may have carried the soldier’s shield, handing it to the soldier mere moments prior to a battle.

Figure 1.2: Hoplite soldier.

King Philip II of Macedon (359 – 336 BCE) rebuilt the Greek Army with a view to the imminent war against the Persians. The purpose was to increase the mobility and speed of his army: for this reason, Philip II gave orders that all soldiers were to carry their own equipment and that wheeled vehicles were not to be used, replacing them with pack mules and horses. This action reduced the number of camp followers by almost two thirds, consequently decreasing the army’s logistical load and increased its march speed. The result was a Macedonian soldier who was a beast of burden, carrying 13.5 kilograms of grain, equivalent to ten days’ rations, plus their 22.5 kilograms of battle equipment and arms, for a total load of 36 kilograms. On the other side, with the aim to reduce costs, the Macedonian soldiers had to purchase their own equipment by themselves: in such a way the more expensive components of the Hoplite armor were replaced by cheaper composite materials or simply abandoned altogether, lightening the soldier’s load. Moreover, the Macedonia spear, or sarissa, was introduced in place of the Hoplite spear. The sarissa weighted between 5.5 and 7.5 kilograms depending on length, being heavier than the 0.1 kilogram Hoplite spear; this spear was used as both an offensive and defensive weapon and allowed for the abandonment of the armored breastplate and the

10 introduction of a smaller shield, so that while the weapon load increased, armor load decreased [3].

Figure 1.3: Macedonian soldier.

In order to effectively carry this load and yet still be able to function in combat, the Macedonian soldier needed to be physically conditioned and prepared: this was accomplished by vigorous battle hardening drills, which included marching 55 ÷ 64 kilometers per day while carrying armor, weapons, equipment and food at a rate of 8 kilometers per hour. The combined results of these changes was the creation of the fastest army the world had ever seen, with the entire army capable of covering 21 kilometers a day carrying a load of between 27.5 and 36.5 kilograms, equivalent to 40 to 54 per cent of the body weight. In around 100 BCE, following the King Philip II trend, Gaius Marius introduced sweeping reforms to the Roman army, which included the reduction of pack animals to one mule per fifty soldiers. Considering equal of around 113.5 kilograms the maximum load a mule can carry, each soldier could only unload around 2.5 kilograms onto the mule, supposing, of course, that the mule was not carrying its own food or any additional

11 supplies: this reform, aimed at increasing the logistical efficiency of the Roman army, led to the labelling of the Roman infantryman as Muli Mariani. Now carrying their personal possessions and some food and drink, the Roman soldier hauled a load of up to 45.5 kilograms. However, the medium load carried by a roman soldier of around 36.5 kilograms can be considered, although some authors [4] suggest a lighter load based on operational requirements: a “road marching load” of 26 kilograms, an “approach marching load” of 20 kilograms, and a “tactical combat load”, with which the Legionnaires could engage the enemy in physical contact for an entire day, of 15 kilograms. The typical equipment of a legionary consisted of armor, commonly lorica hamata, lorica squamata, or I – III century CE lorica segmentata, shield (scutum), helmet (galea), two javelins (one heavy pilum and one light verutum), a short sword (gladius), a dagger (pugio), a pair of heavy sandals (caligae), a sarcina (marching pack), about fourteen days’ worth of food, a waterskin (bladder for posca, a popular drink in ancient Rome and Greece), cooking equipment, two stakes (sudes murale) for the construction of palisades, and a shovel or wicker basket [5]. Based on specimen samples from Pompeii and Herculaneum, which estimate the average Roman male body weight of the era as 66 kilograms, the average Roman soldier would have carried a load of around 55 per cent of their body weight, from a minimum of 23 to a maximum of 69 per cent. As the Roman Legionnaires could be expected to march up to 32 kilometers per day and then fortify their night camp, they needed to be physically conditioned for such a task: in order to prepare the Roman soldier to carry such loads and march for long distances, Publius Flavius Vegetius Renatus, in his work Epitoma rei militaris [6], recommended that recruits carry a load of up to 60 Roman pounds, equivalent to 19.6 kilograms, route marching at the “military step” of 32 kilometers for five hours, with a rate of 6.4 kilometres per hour or at the “full step” of 39 kilometers in the same time, equivalent to a rate of 7.7 kilometres per hour. This load did not include the soldier’s clothing and weapons, and was designed to condition the soldier to carry rations as well as arms during campaigns.

Figure 1.4: Legionary.

However, infantry forces and marching soldiers started to became a subsidiary arm, being superseded by the armored mounted knights that turned out to be the center point on the battlefield thanks to their rapid shock action. The Byzantine scutati, or heavy infantrymen, carried many weapons against enemy cavalry such as spears to ward off cavalry and axes to cut the legs off of horses [7]. They wore a mail shirt or armor weighing 16 kilograms, with or without greaves and gauntlets, in addition to a spear or lance, sword and spiked axe, for an approximate total load of between 19.5 and 36.5 kilograms, equivalent to a load between 30 to 55 per cent of body weight. Following the Roman army trend, each soldier was required to carry their own equipment for the battle, personal necessities and several days’ food. Although baggage trains did still accompany the army, they carried the equipment and supplies needed for sustained operations and siege craft and did little to reduce the individual soldier’s load.

Figure 1.5: Scutati.

The longbow, crossbow and invention of powdered weapons led to the return of the foot soldier; another reason for a return of the infantry armies was the cheaper cost to train and arm a soldier with a pike compared to that of a mounted knight. During the English Civil War (1638 – 51), the English pikemen took to the field. Typically dressed in Corselet armor, which together with helmets and leg guards weighed around 11 kilograms, these foot soldiers carried a knapsack containing food and spare clothing that brought their carried load to between 22.5 to 27.5 kilograms, excluding the weight of their pike and other melee weapons, like sword or axe. Considering that they equipped the shorter seven feet pike (2.1 m) weighing between 1.8 and 2.3 kilograms instead of the traditional, longer and heavier 16.5 ÷ 18 feet (5 ÷ 5.5 m) pike, the total load carried by the pikemen is considered to be around 27 kilograms, equal to about the 40 per cent of their body weight.

Figure 1.6: English Pikeman.

In the charts of Figure 1.7 and Figure 1.8 are respectively reported the absolute values of the load carried by the soldiers in the time period analyzed in this paragraph, and the load in relation of the body weight of the soldiers.

Load carried during 700 BCE - 1651 CE (absolute value)

50 45 40 35

kg 25 20 15 10 Minimum Load 5 0 Maximum Load Mean Load Scutati Hoplite Assyrian Legionary Macedonian English Pikeman 700 BCE - 1651 CE Pre - Musket Era

Figure 1.7: Evolution of the load carried by soldiers during 700 BCE – 1651 CE period (kg). 15

Load carried during 700 BCE – 1651 CE (% of body weight)

70 60 50 40

% 30 %min %Max 20 %Mean 10 0 Assyrian Hoplite Macedonian Legionary Scutati English Pikeman 700 BCE - 1651 CE Pre - Musket Era

Figure 1.8: Evolution of the load carried by soldiers during 700 BCE – 1651 CE period (% of body weight).

From the charts shown in Figure 1.7 and 1.8 it can be noticed that the mean value of the load carried by soldiers has not extremely changed during the period, settling around on the 45% of their body weight.

1.2. Musketeers (1651 – 1865 CE) By the start of the Spanish War of Succession (1702 – 14), the pike was replaced by Flintlock muskets and socket bayonets.

Figure 1.9: Flintlock muskets and socket bayonets.

During the American War of Independence and the French Revolutionary wars, the British Redcoats, equipped with muskets, shot and powder, carried a load of around 36.5 kilograms. During the Napoleonic wars, the Redcoat’s loads fluctuated between 22.5 and

36.5 kilograms with the load at the landmark Battle of Waterloo in 1815 being between 27.5 and 32 kilograms.

Figure 1.10: The Redcoats. From left: Private; Officer, Battalion Company; Field Grade Office.

The Redcoat’s counterparts, the French, carried a slightly lighter load of around 27.5 kilograms during the French Revolutionary wars and similar loads into the Napoleonic wars, before loads dropped slightly to around 25 kilograms during the decisive Battle of Waterloo. Under the command of Napoleon, French troops routinely marched 16 ÷ 43 kilometers per day and were expected to be fit for fighting at the end of the march. Marshal Davoust, a French Marshal under Napoleon, generally expected his men to march in column at a pace of 4 kilometers per hour for up to ten hours a day. In a sixteen-day period, Marshal Davoust marched his soldiers 280 kilometers in order to engage the Prussians. Likewise, to win the Battle of Dresden, Napoleon reportedly marched his army a staggering 144 kilometers in 72 hours. With these long continuous marches, it should not surprise that the French soldiers remarked that “Our emperor makes war not with our arms but with our legs”.

Figure 1.11: Garde Impériale (French Imperial Guard). From left: Sapper; Drummer, Officer, Petty Officer; Soldier; typical Rifleman.

During the Crimean War (1853 – 56), the British loads remained similar to those at Waterloo, ranging from 26 to 31 kilograms, while the French loads increased to between 33 to 36.5 kilograms. A few years later, in 1861, the American Civil War began. Armed with shoulder arms, sixty rounds of ammunition, a piece of shelter tent and 7 ÷ 11.5 kilograms in their knapsack, the soldiers of the Union Army of the Potomac carried a total load of between 20.5 and 22.5 kilograms. In addition to this load, each eight-man section also had to carry additional stores of picks, kettle, axes and various other tools. However Union Army loads were not universal; the 24th Wisconsin Volunteer Infantry Regiment of the Union Army’s Middle Military Division, for example, were noted as carrying around 22.5 kilograms in their knapsacks plus their 4.5 kilogram musket: a total load of around 27 kilograms.

Figure 1.12: Union Army. First row, from left: Lieutenant General; Brigadier general; Colonel of Infantry; Captain of Artillery. Second row, from left: Major of Cavalry; Lieutenant Colonel, Surgeon; Sergeant Major, Artillery; Sergeant, Infantry; Third row, from left: Private, Infantry; Corporal, Cavalry; Private, Light Artillery; Great Coat for all mounted men. 19

Figure 1.13: Confederate Army. First row, from left: General; Colonel, Infantry; Colonel, Engineers, Major, Cavalry. Second row, from left: Surgeon, Major Medical Department; Captain, Artillery; First Lieutenant, Infantry; Sergeant, Cavalry. Third row, from left: Corporal, Artillery; Private, Infantry; Overcoat (Infantry); Overcoat (Cavalry). 20

The load of the Confederate Army’s infantry soldier varied greatly, ranging between 13.5 to 36.5 kilograms. The 21st Virginia Infantry F Company, for example, were claimed to carry loads of 13.5 ÷ 18 kilograms, and in some cases up to 22.5 kilograms, in their knapsacks. However, limited supplies and laxer regulations meant that the Confederate soldier often carried less weight than his Union counterpart, and their 7 ÷ 11.5 kilograms knapsacks vanished early in the war. With the average weight of the American soldier in the Civil War being around 62 kilograms the average Confederate soldier’s load ranged between 22 ÷ 59 per cent of their body weight, while the Union Army soldier’s load ranged between 33 ÷ 44 per cent of their body weight. In the charts of Figure 1.14 and 1.15 are respectively reported the absolute values of the load carried by the soldiers in the time period analyzed in this paragraph, and the load in relation of the body weight of the soldiers.

Load carried during 1651 - 1865 CE (absolute value)

40 35 30 25

kg 20 15 Minimum Load 10 5 Maximum Load 0 Mean Load French French Redcoat Redcoat Union Army Confederates 1803-1815 1853-1856 1861-1865 Napoleonic War Crimean War American Civil War

Figure 1.14: Evolution of the load carried by soldiers during 1651 – 1865 CE period (kg).

Load carried during 1651 - 1865 CE (% of body weight)

60 50 40

% 30

20 %min 10 %Max 0 %Mean French French Redcoat Redcoat Union Army Confederates 1803-1815 1853-1856 1861-1865 Napoleonic War Crimean War American Civil War

Figure 1.15: Evolution of the load carried by soldiers during 1651 – 1865 CE period (% of body weight).

From the charts of Figure 1.14 and Figure 1.15 it can be noticed that the load carried by soldiers in this time period varies a lot, ranging from a load of 35% of body weight carried by Confederate soldiers to the 54% carried by the British soldiers during the Napoleonic Wars.

1.3. World Wars (1914 – 1946 CE) In the Great War, heavy loading reduced the marching ability of the average soldier and was claimed to have altered the tactics of war. During this conflict, German troops carried loads ranging 25 to 45.5 kilograms, although a load of around 32 kilograms was considered average. French soldiers, meanwhile, carried heavier loads of up to 38.5 kilograms. During their North African campaign, the specialized French Foreign Legion were required to carry loads even greater, around 45.5 kilograms, for up to 40 kilometers per day. Both of these forces carried not only heavy loads but had to traverse substantial distances under this weight.

Figure 1.16: German soldier – Great War.

Figure 1.17: German infantry marching – August 07, 1914.

Figure 1.18: French bayonet charge – Great War.

Figure 1.19: French soldiers – Great War.

The loads carried by United States troops were claimed to leave soldiers exhausted during the short distance assaults between trenches, even before contact with the enemy. With the average American soldier weighing around 64.5 kilograms, and carrying a load between 22 and 32 kilograms, these soldiers carried a load between 34 ÷ 50 per cent of their body weight. The British soldiers in 1914 started off with little lighter loads, between 20.5 and 27 kilograms, but soon found their loads increasing to 30 ÷ 40 kilograms. Considering an average weight for the British recruits of 60 kilograms lead to a carrying load between 34 and 67 per cent of their body weight.

Figure 1.20: United States’ soldiers – Great War.

Figure 1.21: British infantry – Morval; September 25, 1916.

The Australians and Canadians carried equivalent loads: the Australian soldiers at Gallipoli carried a load of 33.5 kilograms while the Canadian soldiers carried a load of 30 ÷ 36 kilograms. For the Australian soldiers of the 6th Australian Infantry Division assaulting Mont St Quentin, loads were a little lighter, ranging between an estimated 27 and 28.5 kilograms. Considering an average weight for both Australian and Canadian soldiers equal to 64.5 kilograms, the weight carried by Australian and Canadian was about between 42 ÷ 52 and 47 ÷ 56 per cent of body weight respectively.

Figure 1.22: Australian ANZAC army soldier troops – Gallipoli; Great War. 25

Figure 1.23: Canadian Soldiers going over the top – Vimy Ridge; Great War.

The load carried by soldiers didn’t change too much during World War II. During the D-Day landings at Omaha Beach the Allied troops landed with a load of around 27.5 ÷ 41 kilograms: such a load was attributed to cause deaths in the water. Even if the soldiers made it to the beach, they faced another problem: getting across the beach quickly and under intense enemy fire; also in this case, weight was against the soldiers as “The GI’s were so laden with ammunition and equipment that every step was a strain”. With an average body weight of 65.5 kilograms, the Allied soldier carried a load between 42 ÷ 63 per cent of their body weight, while charging through chest deep water and then across sands, all while exposed to heavy enemy fire.

Figure 1.24: Allied D-Day beach landing – Normandy; late afternoon of June 06, 1944.

On the Eastern Front, Soviet soldiers carried loads of 28 ÷ 35.5 kilograms, while in the North African desert, Australian troops carried loads of between 22 and 32 kilograms into the battles at Bardia and El Alamein (1941 – 42). In the Pacific theatre, the loads carried by Australian soldiers were similar: 20.5 ÷ 41 kilograms in Papua New Guinea (1942) and up to 37.5 kilograms in Borneo (1945). Operating behind the lines in Burma, the British Chindits likewise carried loads of between 32 to 41 kilograms. The opposing forces in the Pacific theatre, the Japanese soldiers, also carried heavy loads, ranging from the standard 28 kilograms up to 56 kilograms for machine gun units. With the average Japanese soldier weighing around 53 kilograms this equated to a load of between 53 per cent and an unreasonable 106 per cent of their body weight.

Figure 1.25: Soviet guerrillas – Leningrad area; October, 1942. 27

Figure 1.26: A patrol from the Australian 2/13th Infantry Battalion – Tobruk; September 08, 1941.

Figure 1.27: Australian soldiers showing a captured Japanese 70 mm howitzer and Juki medium machine gun – Oivi; November 23, 1942. 28

Figure 1.28: British soldiers in the Chindits unit – India; 1942.

Figure 1.29: Japanese soldiers – World War II. 29

In the charts of Figure 1.30 and Figure 1.31 are respectively reported the absolute values of the load carried by the soldiers during the World Wars, and the load in relation of the body weight of the soldiers.

Load carried during 1914 - 1945 CE (absolute values)

60 50 40

kg 30 20 Minimum Load 10 Maximum Load 0 Mean Load US Allies Soviet British French German (Pacific) Japanese Canadian Australian Australian Australian (North Africa) British Chindits 1914-1918 1939-1945 World War I World War II

Figure 1.30: Evolution of the load carried by soldiers during 1914 – 1945 CE period (kg).

Load carried during 1914 - 1945 CE (% of body weight)

120 100 80 60 40 %min 20 %Max 0 %Mean US Allies Soviet British French German (Pacific) Japanese Canadian Australian Australian Australian (North Africa) British Chindits 1914-1918 1939-1945 World War I World War II

Figure 1.31: Evolution of the load carried by soldiers during 1914 – 1945 CE period (% of body weight). 30

From both charts in Figure 1.30 and Figure 1.31, it can be appreciated how the load carried by soldiers during the World Wars have not substantially changed; also the Japanese, which achieved one of the maximum loads in percentage of body weight probably ever carried by a soldier, are characterized by a mean value of the load carried in line with the value observed in the period of the two World Wars.

1.4. Modern Era (1950 CE – present) After viewing a Canadian Exercise conducted in May 1942, Field Marshal Montgomery, in a letter to Canadian General Crerar, recommended a load that would not have an impact on the soldier’s fighting ability, equal to a maximum of 22.5 kilograms. For the Canadians, with an average body weight below 72 kilograms, this would suggest a load of around 31 per cent of their body weight. During the Korean War in 1950, the Canadians were to carry precisely that recommended load.

Figure 1.32: Canadian riflemen catch up on the hometown news while waiting for orders to move up against the Chinese communist forces on the Korean front – Korea; February, 1951.

Figure 1.32: US soldiers during a battle – Korean War.

The United States’ soldiers started the war carrying a load ranging from 18 to 22.5 kilograms, however this load, considerably lower if compared to the one carried during the World Wars, had a negative effect on the soldiers: infantry troops arrived at their march destination in a state of fatigue, with men complaining that they straggled as a result of carrying things they never used in combat. Even so, the loads kept climbing, with claims that American soldiers had to carry 37.5 kilograms at a speed of around 4 kilometers per hour (during the day when on roads) for a distance of 19 ÷ 32 kilometers per day. Moreover, in December 1950, the American 7th Marines of the 1st Battalion were reportedly required to carry loads of around 54.5 kilograms through the snows and steep slopes of Toktong Ridge.

Figure 1.33: Republic of Korea (RoK) soldiers move in single file toward Korea's east- central front near Lookout Mountain – east of Pukhan River; June 28, 1953.

While the South Koreans of the Republic of Korea’s (RoK) army carried heavy loads of over 36.5 kilograms, the North Korean People’s Army (NKPA) and the Chinese Communist Forces (CCF) carried lighter loads of around 18.5 kilograms, that, supposing a medium weight of 55 kilograms for the Asian soldier, correspond on a load equal to 66 and 34 per cent of body weight respectively.

Figure 1.34: North Korean People’s Army tank regiment – Korean War. 33

Figure 1.35: Chinese forces crossing the Yalu River and joined the war – Korean War.

With these lighter loads the NKPA and CCF were able to move faster and further per day than their American counterparts, reaching a rate of 4.8 kilometers per hour for 35 ÷ 40 kilometers per day. An exception to the lighter Chinese loads was with the Chinese People’s Volunteers Force (CPVF) having to carry loads of around 27.5 ÷ 32 kilograms when their logistic support let them down.

Figure 1.36: US soldiers checking houses during a patrol – Vietnam War. 34

During the Vietnam War (1955 – 75), the load carried by United States’ soldier increased insomuch as they adopted the term “grunt” recalling the term “Marius Mules” embraced by Roman Legionnaires: the typical load for the American infantry soldier patrolling through the jungles of Vietnam was 27.5 ÷ 32 kilograms, reaching for the Marines 36.5 to 45.5 kilograms. Australian troops generally carried heavier loads of 32 ÷ 32.5 kilograms and in some cases even more: Several members from the 8th Battalion, Royal Australian Regiment (RAR) weighed their packs and found they carried loads of between 36.5 and 54 kilograms. Interestingly, even when their mission changed from reconnaissance to pacification, and the content of the loads changed, the overall load weight remained the same. As such, Australian soldiers were constantly taking measures to lighten their loads by removing non-essential stores. These loads were similar for the soldiers of the 4th Battalion RAR, who likewise carried loads of 30 ÷ 40 kilograms for a rifleman and up to 47.5 ÷ 56 kilograms for the radio operators.

Figure 1.37: Australian soldiers from 7th RAR waiting to be picked up by US Army helicopters following a cordon and search operation – Phuoc Hai; August 26, 1967.

The native Viet Cong were not so encumbered. Unlike the heavy loads carried by soldiers from foreign forces, the Viet Cong reportedly carried noticeably lighter loads of around 12 kilograms: these loads are perhaps indicative of the advantages of fighting on “own” soil. 35

Figure 1.38: A Viet Cong soldier crouches in a bunker with an SKS rifle – January 1, 1968.

During the Falklands conflict in 1982, the British infantry and Royal Marines carried loads between 32 ÷ 36.5 kilograms in Fighting Order (essential fighting stores) and 45.5 ÷ 54.5 kilograms in Marching Order (short duration sustainment stores together with fighting stores), although the 45 Royal Commando Marines carried a load between 54.5 ÷ 66 kilograms during a long march.

Figure 1.39: British troops from the Parachute Regiment – Mount Longdon; June 12, 1982. 36

A year later, during Operation URGENT FURY, American troops landed in Grenada carrying loads of up to 54.5 kilograms; during the same operation, American Army Rangers parachuted onto the runway at Salinas airfield, carrying even heavier loads of around 76 kilograms [8].

Figure 1.40: Rangers from 1st Plt., C Co., 1st battalion lead the company as they move along Fury Drop Zone – Grenada; 25 October 1983.

Figure 1.41: An American soldier wearing the Desert Battle Dress Uniform – Gulf War.

In the Gulf War (1990 – 1991), during Operation DESERT SHIELD and DESERT STORM, American soldiers carried loads up to 45.5 kilograms. In Somalia, during Operation UNITED SHIELD (1995), American Army infantry soldiers came ashore with a load of around 49.5 kilograms. Weighing an average of 75 kilograms, these soldiers were carrying a load of around 70 per cent of their body weight. Little has changed in the more recent conflicts. In East Timor, on Operation CITADEL (2002), Australian soldiers carried loads ranging from 45 to 50 kilograms for gunners and signalers.

Figure 1.42: Australian Defence Forces personnel on patrol – East Timor.

A recent comprehensive study of the 82nd Airborne Division, on Operation ENDURING FREEDOM III in Afghanistan, found that the American soldiers carried a “fighting load” of 29 kilograms, an “approach march load” of 43.5 kilograms, and an “emergence approach march load” of 57.5 kilograms. With the average weight of the soldiers in this study being 79.5 kilograms, this equated to loads of 36 per cent, 55 per cent and 73 per cent of body weight respectively. Nowadays, American soldiers continue to carry loads between 45.5 ÷ 54.5 kilograms in Afghanistan and Iraq, marching around 10 ÷ 15 kilometers per day. In Figure 1.44 and Figure 1.45 the absolute value of the load carried by soldier from 1950 and the same value expressed as percentage of body weight are reported respectively.

Figure 1.43: American soldiers fighting in Afghanistan – Helmand Province; July 3, 2009.

Load carried during 1950 CE - present (absolute values)

kg 0 10 20 30 40 50 60 70 80

Canadian

RoK 1950-1953 Korean War Korean NKPA

CPFV

US Minimum Load

Australian Maximum Load

1955-1975 Mean Load Vietnam War Vietnam Viet Cong

Falklands - British 1982

Grenada - US 1982

91 Gulf War - US 1990-

Somalia - US 1995

East Timor - Australian 2002

on Iraq/Afghanistan - US 2003-

Figure 1.44: Evolution of the load carried by soldiers during 1950 CE – present period (kg). 39

Load carried during 1950 CE - present (% of body weight)

% 0 20 40 60 80 100

Canadian

RoK 1950-1953 Korean War Korean NKPA

CPFV

US %min

Australian %Max

1955-1975 %Mean Vietnam War Vietnam Viet Cong

Falklands - British 1982

Grenada - US 1982

91 Gulf War - US 1990-

Somalia - US 1995

East Timor - Australian 2002

on Iraq/Afghanistan - US 2003-

Figure 1.45: Evolution of the load carried by soldiers during 1950 CE – present period (% of body weight).

From the charts it can be appreciate how the load carried by soldiers, especially those from the United States, is increasing in the last decades. Moreover, it can be observed that a heavier load does not correspond to a “better” equipment, as highlighted by the heavier load carried by American and Australian during the Vietnam War compared to the 3 ÷ 4.5 times lighter Viet Cong equipment, who gave a very hard time to the US coalition.

1.5. Conclusions All the data related to the soldier’s load, for most but not all countries, have been gathered and reported in Figure 1.46 (absolute values) and Figure 1.47 (per cent of the body weight). Analyzing both Figures, it appears that the load have remained generally unchanged for over two millennia, until increasing noticeably after the Vietnam War. Furthermore, in the context of relative loads, it can be seen that the Roman loads of around 36.5 kilograms or 55 per cent of their body weight is very similar to the “approach march loads” of the 82nd Airborne Division in Afghanistan, where the soldiers carried loads of 43.5 kilograms or 55 per cent of their body weight. This example shows how absolute loads may have increased in recent times, while the relative loads carried by the soldier may have in fact stayed the same. Finally, although logistical aides (like carts, mules, motorized vehicles and aircraft) have changed through history, the soldier’s load has not reduced noticeably. A plausible reason for this lack of load reduction may be due to the fact that these logistical aides did little to unload the solider in the first instance and were used primarily to carry other logistical stores.

In order to reduce the negative effect of the load carried by the soldier, several solutions can be adopted. This solutions, analyzed in the following chapter, are:  Improvement in Materials  Unmanned Ground Vehicle (UGV)  Powered Exoskeleton.

Load carried by soldiers

kg 0 10 20 30 40 50 60 70 80

Assyrian

Hoplite

Macedonian

Legionary Pre - Musket Era 700 BCE - 1651 CE Scutati

English Pikeman

Redcoat

War French 1803-1815 Napoleonic Redcoat

War French Crimean 1853-1856 Union Army

Confederates Civil War American 1861-1865 German

French

British 1914-1918 World War I Australian Minimum Load Canadian Maximum Load Allies Mean Load Soviet

Australian…

Australian… 1939-1945 World War II British Chindits

Japanese

Canadian

RoK 1950-1953 Korean War NKPA

CPFV

Australian 1955-1975

Vietnam War Viet Cong

Falklands - British 1982 Grenada - US 1982 Gulf War - US -91 1990 Somalia - US 1995 East Timor - Australian 2002 Iraq/Afghanistan - US -on 2003

Figure 1.46: Evolution of the load carried by soldiers (kg). 42

Load carried by soldiers in % of their body weight

% 0 20 40 60 80 100

Assyrian

Hoplite

Macedonian

Legionary Pre - Musket Era 700 BCE - 1651 CE Scutati

English Pikeman

Redcoat

War French 1803-1815 Napoleonic Redcoat

War French Crimean 1853-1856 Union Army

Confederates Civil War American 1861-1865 German

French

British 1914-1918 World War I Australian %min Canadian %Max Allies %Mean Soviet

Australian…

Australian… 1939-1945 World War II British Chindits

Japanese

Canadian

RoK 1950-1953 Korean War NKPA

CPFV

Australian 1955-1975

Vietnam War Viet Cong

Falklands - British 1982 Grenada - US 1982 Gulf War - US -91 1990 Somalia - US 1995 East Timor - Australian 2002 Iraq/Afghanistan - US -on 2003

Figure 1.47: Evolution of the load carried by soldiers (% of body weight). 43

2. Materials

2.1. Historical Background The need to protect soldiers by means of an armor has driven to the research of effectives materials in harms’ prevention and to a technological development of the same since ancient times. In this sense, the Dendra panoply is an historical evidence of a protective covering made of bronze plates found in Greece and dated back to the Micenean-Era.

Figure 2.1: Dendra panoply, XV century BCE.

A panoply is a completed set of attire including weapons and armor. The entire suit consisted of 15 pieces joined together with cord and an additional pair of greaves and vambraces accompanying it. The remains of the boar-tusk helmet were found with it, as well, and have been reconstructed to look similar to how they would have some 3 400 years ago, on a new base of leather or stiff fabric. These joint pieces, four additional plates and the helmet make the panoply the most complete and body-covering armor of the Bronze Age. The set consist of protection for the upper arms, neck, and torso to just above the knees. Using cord of leather or twined fabric, they were all joined to create a single, 44 protective suit. The gorget was an exception to this method of attachment, as it surely had to be removed often when not in combat, and likely rested on pins or something of that sort, on top of the shoulders. The boar tusk helmet was constructed of sliced tusks stitched to a leather or material cap, running in horizontal rows, and a pair of bronze cheek guards [9, 10]. During the Roman era, since monarchy, throughout the republican age and until the collapse of the empire, armors were principally made of leather and metal alloys (iron and bronze, above all). The real evolution was about the manufacture, more than the used materials themselves. The Lorica Hamata was an example of armor born in that period and which use lasted until the early twentieth century. It was composed by an elevate number of steel rings kept together by means of rivets or simply wedged in together. From 10 000 to 30 000 rings were needed to manufacture a Lorica Hamata, where each ring had an external radius from 3 to 10 millimeters. The weight of this kind of armor could reach 15 kilograms but it was often mitigate by wearing a leather belt which unloads part of the weight on the hips [11].

Figure 2.2: Lorica Hamata, IV century BCE – I century CE.

Other representatives items utilized that periods were the: 1. Lorica Muscolata, a metal alloy armor which reproduced the musculature of the abdomen and chest; 2. Lorica Segmentata, an armor composed by a series of steel sheets joined by leather strips, moreover it is the most recognizable roman armor in the popular imagination;

3. Linothorax, from 11 to 18 layers of linen composed a 1 centimeter thick armor which resulted extremely resistant in spite of its lightness.

The late middle ages see the arrival of to the Plate Armor which see its development mostly in the context of the Hundred Years’ War. It was originally made of bronze, easy to shape, but it was early replaced by iron which was easier to retrieve and which gained a certain popularity thanks to its strength. The improvement of making steel over the years made this one the preferred choice in the plate armor building. This type of personal covering declined in the seventeenth century due to the arrival of flintlock muskets which could easily penetrate those shields from long distance. The plate armors remained a prerogative of cuirassiers whom wears a lighter version of the protective covering developed in the late middle-age [9, 12].

Figure 2.3: French plate armor for heavy cavalry, ca. 1600.

In Uomini contro, a Francesco Rosi’s movie (1970), a dramatic scene which displays an event of the first world war is present, in which a general sends his armored soldiers to cut the wires of the enemy trench. The armor worn by the privates is the Corazza Farina [13]. This cuirass was composed by a trapezoidal plate (30×40 cm) made of 5 layers of chrome-nickel steel curved on the sides and two shoulder pads. 23 rivets strengthened the structure. The armor was declared resistant to bullets caliber 6.5 mm fired at a distance of 125 meters. As, the mentioned scene shows, the armors results inadequate to the enemy’s fire, in particular to the bullets exploded by the large caliber machine guns vastly utilized in that conflict.

Figure 2.4: Corazza farina, Great War.

The Corazza Farina wasn’t the only one of its kind. Other examples are the Brewster Body Shield [14] developed for United States Army and the German Infaterie-Panzer [15]. The body armors have to absorb energy concentrated in a very small frontal area where the bullet strikes. These steel shields couldn’t withstand that energy and often they add damage to the soldiers due the metal sheets which bended under the projectile penetration.

Figure 2.5: Brewster Body Shield (left) and German Infaterie-Panzer (right), Great War.

During the Second World War the Flak Jackets [16, 17] made their appearance on a large scale. Their objective was to protect against case fragments from explosive artillery, round shots, land mines and low-velocity projectiles.

Figure 2.6: Flak Jacket, World War II.

These jackets were made of manganese steel plates sewn into a waistcoat made of ballistic nylon. The manganese steel, also known as Mangalloy [18], is a steel containing 11 ÷ 15% of manganese. This material has the capability to achieve three times its hardness during condition of impact without any increase of brittleness. Ballistic nylon, produced by DuPont, is a thick, tough, synthetic nylon fabric. It is created using a very high-denier (the denier is a liner unit mass density for fibers) nylon thread (typically 1 000d and above) though the defining feature of ballistic nylon is not the thread denier (and its accompanying weight), but rather the specific weave used to turn the thread into fabric. A ballistic weave is a particularly tight and dense weave that maximizes the fabric's durability and tear resistance. The most common ballistic weave is a 2×2 basket weave, as pictured in Figure 2.7. This weave pattern provides exceptional tear resistance in all directions, while the large denier of the individual nylon threads effectively resists abrasion.

Figure 2.7: Blue Cordura garment.

It was in 1945, during the battle of Okinawa, that the US Army used Doron Plate [19], a fiberglass-based laminate, for the soldiers’ vests. The plates were 1/8 inch (3.2 mm) thick and cut into five inches (12.7 cm) squares then inserted into pockets on a nylon vest that covered the front and back portions of the torso as well as the shoulders. The vest weighed approximately 8 pounds (3.6 kg). The plates consist of fiberglass filaments bonded together with resin under pressure. The plates could be molded to fit the contours of the chest or back. Dow Company discovered the technology for the Doron plate in May 1943 because a shortage of metal during World War II had stimulated research into non- metallic forms of body armor. The Doron plate could not stop direct fire from bullets but was effective at stopping relatively slow moving flak and shrapnel.

In the 1950's and 1960's technology advanced, and the newer forms of nylon and other artificial fibers shows signs of improvement in weight reduction. However, their ballistic protection suffered as a result. The design itself haven't changed much: nylon outer skin with metallic or composite inserts made of Doron or metal/non-metal composites. A breakthrough came in 1967, and Natick Laboratories (part of US Army) created the first ceramic inserts for the vests. Nicknamed Chicken Plates [20], they were not that popular. Most soldiers who went to Vietnam with them actually sat on them in the helicopter to let it protect against shots fired from below instead of wearing them. However, these plates do stop rifle bullets at acceptable weight. Large number of them were issued to helicopter crew who are expected to fly into enemy fire day in and day out. These Chicken Plates were made of either boron carbide, silicon carbide, or aluminum oxide.

Figure 2.8: Ceramic core personal armor known as Chicken Plate deployed in Vietnam to US troops.

In 1969, American Body Armor was founded to create body armor for law enforcement, and their first product, trademarked as “Barrier Vest”, was a success and widely adopted by law enforcement agencies. Other makers started marketing body armor as well, leading the newly formed National Institute of Justice to launch a study to develop accurate non-partial way to evaluate the protection level of such body armor. 50

Stephanie Kwolek [21], a chemist researcher at the DuPont Company, discovered a liquid crystalline polymeric solution which led to the invention of Kevlar and to its spread on the market in the early seventies. Kevlar resulted five times stronger than steel when woven into fabric and layered. The first popular armor featuring Kevlar was the K-15, launched in 1975, featuring 15-layers of Kevlar weave backed by a ballistic steel "shock plate" over the heart for maximum protection, and was awarded a patent. Similarly sized and positioned "trauma plates" are still used today on the front ballistic panels of most concealable vests, reducing blunt trauma and increasing ballistic protection in the centre- mass heart/sternum area. In 1976, Richard Davis, founder of Second Chance Body Armour designed this company's first all-Kevlar vest, named the Model Y. In the photo shown in Figure 2.9, Richard Davis demonstrate the aftermath of a self-inflicted gunshot.

Figure 2.9: Richard Davis demonstrate the aftermath of a self-inflicted gunshot.

He claims to have been inspired by a robbery where he had a gunfight against 3 notorious robbers. His all-Kevlar design was light enough to be worn concealed under clothing for daily use by police officers and civilians.

US Army in 1980's adopted the PASGT armor and helmet, both of which are made out of Kevlar.

Figure 2.10: Military issue PASGT body armor.

However, PASGT is only officially rated "Level I" (see protection level ratings in Table 2.1). Anecdotally the armor had been rated higher, but such tests were never proven. It was designed as fragmentation and shrapnel armor only.

Protection Level Designed to Resist

Level I .22LR, 380 ACP, light pistol

Level IIA 9mm, .40 S&W, .45 ACP, medium pistol

Level II 9mm FMJ, .357 Magnum, medium pistol

Level IIIA .357 SIG FMJ, .44 Magnum, heavy pistol

Level III NATO 7.62mm, rifle

Level IV .30-06 Armor Piercing, rifle Table 2.1: Ballistic body armor protection levels.

US Army also fielded an improved armor commonly known as Ranger Body Armor (only issued to 75th Ranger Regiment) but that didn't offer enough all around protection. The “Black Hawk Down” incident demonstrated the need for all around protection when several Rangers were injured from being shot in the rear.

Figure 2.11: The Improved Outer Tactical Vest, an enhanced version of the Interceptor Body Armor.

In 2004 – 2005 US Army phased out the PASGT (and Ranger Body Armor) and replaced with Interceptor Body Armor, which is rated “Level III”, able to stop rifle bullets, while about 5 pounds (2.3 kg) lighter than the Ranger and PASGT body armor. However, with addition of side plates, collar, and groin plates, the overall weight has actually crept up, not down

2.2. State of the Art Newer materials such as Spectra, Zylon, and other fibers claim to outperform Kevlar. However, they are also much more expensive and offers different trade-offs. Zylon, for example, is found to be not weather resistant, and when exposed to the elements, quickly degrades.

Figure 2.12: Spectra shield production.

Spectra fiber [22], manufactured by AlliedSignal (now Honeywell), is an ultra-high- strength polyethylene fiber. Ultra-high molecular weight polyethylene is dissolved in a solvent and spun through a series of small holes, called spinnerets. This solution is solidified by cooling, and the cooled fiber has a gel-like appearance. The Spectra fiber is then used to make Spectra Shield composite. A layer of Spectra Shield composite consists of two unidirectional layers of Spectra fiber, arranged to cross each other at 0 and 90 degree angles and held in place by a flexible resin. Both the fiber and resin layers are 54 sealed between two thin sheets of polyethylene film, which is similar in appearance to plastic food wrap. The resulting non-woven fabric is incredibly strong, lightweight and has excellent ballistic protection capabilities. Spectra Shield is made in a variety of styles for use in both concealable and hard armor applications.

Gold Flex® [22] is a fabric manufactured by Honeywell from synthetic fiber and often used in ballistic vests. AlliedSignal also uses the Shield Technology process to manufacture another type of shield composite called Gold Shield. Gold Shield is manufactured using aramid fibers in place of the Spectra fiber. Gold Shield is currently made in three types: Gold Shield LCR and GoldFlex, which are used in a concealable bullet proof vest and Gold Shield PCR, which is used in the manufacture of hard armor, such as plates and helmets. Another manufacturer, Akzo Nobel, has developed various forms of its aramid fiber TWARON [23] for bullet proof vests. According to Akzo Nobel, this fiber uses 1 000 or more finely spun single filaments that act as an energy sponge, absorbing a bullet’s impact and quickly dissipating its energy through engaged and adjacent fibers. Because more filaments are used, the impact is dispersed more quickly.

Figure 2.13: Gold Flex.

A further fiber used to manufacture body armor is Dyneema [24]. Originated in the Netherlands, Dyneema has an extremely high strength-to-weight ratio (a 1 mm diameter rope of Dyneema can bear up to a 240 kg load), and has high energy absorption characteristics.

Figure 2.14: Dyneema.

An interesting modern design is Dragon Skin [25, 26], which is a remix of old idea and new design. Dragon Skin lightweight ergonomic armor developed by Pinnacle Armor is used for concealed and body armor.

Figure 2.15: Dragon Skin body armor.

Dragon Skin utilizes flexible armor made up of bullet proof ceramic leaves, creating a flexible layer shaped like fish scales. This thin, lightweight armor flexes and molds to the contours of the body and allows for about 44% greater coverage than a rigid 10”×12” (25.4×30.5 cm) ESAPI plate (Enhanched Small Arms Protective Inserts, a ceramic trauma plate) which is a typical coverage. The discs are composed of silicon carbide ceramic matrices and laminates, much like the larger ceramic plates in other types of bullet resistant vests. The armor is available in three basic protection levels: SOV-2000, which has previously had certification to Level III protection; SOV-3000, which is rated as Level IV by

56 the manufacturer, but has not officially certified as such; and a rating-unspecified “Level V” variant not available to the general public.

Figure 2.16: X-ray of Dragon Skin body armor.

SOV-2000 armor is made of an overlapping series of high tensile strength ceramic discs encased in an sonic skin textile cover. Different layout configurations with variations in coverage are available. AMI level III plates are fabricated using an outer 3 millimeters (0.12 inch) MARS steel layer bonded to a compressed Dyneema backing, with a linex coating for spall reduction, resulting in a total plate thickness of approximately 1 inch (25 mm). AMI level III 12”×14.5” (300×370 mm) plates weigh about 10 pounds (4.5 kg) and 10”×12” (250×300 mm) plates are about 9 pounds (4.1 kg).

SOV-2000 is made of overlapping approximately 0.25”×2” (6.4×51 mm) ceramic discs encased in a fabric cover. In evaluating the Dragon Skin system, it is important to note that while the external measurements of the Dragon Skin panel are 11.5”×13.5” (290×340 mm), the area of Level III coverage provided by the encased ceramic discs is 10”×12” (250×300 mm); the fabric edges are not intended to provide ballistic protection. The weight of the SOV-2000 armor providing 10”×12”of Level III protection was approximately 5.5 pounds (2.5 kg).

2.3. Future development Latest generation of materials and nano-technology promises even better material in the future. Spider silk is even tougher than regular silk and if it can be produced on a massive scale, plus nano-construction of composite material, new body armor will be lighter and stronger than ever. Scientists recently have genetically modified silkworms to generate a special mix of regular silk and spider silk. The road ahead looks promising. Other developments such as shear hardening liquid (flexible under normal wear, but hardens when hit), magnetorheological fluid (liquid under normal conditions, but magnetic field turns it stiff), as well as nano-tubes promises interesting composites that promises high strength and low weight inserts for ballistic vests.

2.3.1. Shear-thickening Fluid The term liquid body armor [27, 28] can be a little misleading. For some people, it brings to mind the idea of moving fluid sandwiched between two layers of solid material. However, both types of liquid armor in development work without a visible liquid layer. Instead, they use Kevlar that has been soaked in one of two fluids. The first is a shear-thickening fluid (STF), which behaves like a solid when it encounters mechanical stress or shear. In other words, it moves like a liquid until an object strikes or agitates it forcefully. Then, it hardens in a few milliseconds. This is the opposite of a shear-thinning fluid, like paint, which becomes thinner when it is agitated or shaken.

Figure 2.17: Shear-thickening fluid adopted in liquid body armor.

Figure 2.18: Before impact, the particles in shear-thickening fluid are in a state of equilibrium. After impact, they clump together, forming solid structures. 59

You can see what shear-thickening fluid looks like by examining a solution of nearly equal parts of cornstarch and water. If you stir it slowly, the substance moves like a liquid. But if you hit it, its surface abruptly solidifies. You can also shape it into a ball, but when you stop applying pressure, the ball falls apart. Here's how the process works. The fluid is a colloid, made of tiny particles suspended in a liquid. The particles repel each other slightly, so they float easily throughout the liquid without clumping together or settling to the bottom. But the energy of a sudden impact overwhelms the repulsive forces between the particles -- they stick together, forming masses called hydroclusters. When the energy from the impact dissipates, the particles begin to repel one another again. The hydroclusters fall apart, and the apparently solid substance reverts to a liquid. The fluid used in body armor is made of silica particles suspended in polyethylene glycol. Silica is a component of sand and quartz, and polyethylene glycol is a polymer commonly used in laxatives and lubricants. The silica particles are only a few nanometers in diameter, so many reports describe this fluid as a form of nanotechnology. To make liquid body armor using shear-thickening fluid, researchers first dilute the fluid in ethanol. They saturate the Kevlar with the diluted fluid and place it in an oven to evaporate the ethanol. The STF then permeates the Kevlar, and the Kevlar strands hold the particle-filled fluid in place. When an object strikes or stabs the Kevlar, the fluid immediately hardens, making the Kevlar stronger. The hardening process happens in mere milliseconds, and the armor becomes flexible again afterward.

Figure 2.19: Treated Kevlar after impact from a bullet.

In laboratory tests, STF-treated Kevlar is as flexible as plain, or neat, Kevlar. The difference is that it's stronger, so armor using STF requires fewer layers of material. Four layers of STF-treated Kevlar can dissipate the same amount of energy as 14 layers of neat Kevlar. In addition, STF-treated fibers don't stretch as far on impact as ordinary fibers, meaning that bullets don't penetrate as deeply into the armor or a person's tissue underneath. The researchers theorize that this is because it takes more energy for the bullet to stretch the STF-treated fibers. Research on STF-based liquid body armor is ongoing at the U.S. Army Research Laboratory and the University of Delaware. Researchers at MIT, on the other hand, are examining a different fluid for use in body armor.

2.3.2. Magnetorheological Fluid The other fluid that can reinforce Kevlar armor is magnetorheological (MR) fluid [29]. MR fluids are oils that are filled with iron particles. Often, surfactants surround the particles to protect them and help keep them suspended within the fluid. Typically, the iron particles comprise between 20 and 40 percent of the fluid's volume. The particles are tiny, measuring between 3 and 10 microns. However, they have a powerful effect on the fluid's consistency. When exposed to a magnetic field, the particles line up, thickening the fluid dramatically. The term "magnetorheological" comes from this effect. Rheology is a branch of mechanics that focuses on the relationship between force and the way a material changes shape. The force of magnetism can change both the shape and the viscosity of MR fluids. The hardening process takes around twenty thousandths of a second. The effect can vary dramatically depending on the composition of the fluid and the size, shape and strength of the magnetic field. For example, MIT researchers started with spherical iron particles, which can slip past one another, even in the presence of the magnetic field. This limits how hard the armor can become, so researchers are studying other particle shapes that may be more effective. As with STF, you can see what MR fluids look like using ordinary items. Iron filings mixed with oil create a good representation. When no magnetic field is present, the fluid moves easily. But the influence of a magnet can cause the fluid to become thicker or to take a shape other than that of its container. Sometimes, the difference is very visually dramatic, with the fluid forming distinctive peaks, troughs and other shapes. Artists have even used magnets and MR fluids or similar ferrofluids to create works of art.

Figure 2.20: When exposed to a magnetic field, the particles in magnetorheological fluid align along the field lines.

With the right combination of density, particle shape and field strength, MR fluid can change from a liquid to a very thick solid. As with shear-thickening fluid, this change could dramatically increase the strength of a piece of armor. The trick is activating the fluid's change of state. Since magnets large enough to affect an entire suit would be heavy and impractical to carry around, researchers propose creating tiny circuits running throughout the armor. Without current flowing through the wires, the armor would remain soft and flexible. But at the flip of the switch, electrons would begin to move through the circuits, creating a magnetic field in the process. This field would cause the armor to stiffen and harden instantly. Flipping the switch back to the off position would stop the current, and the armor would become flexible again.

In addition to making stronger, lighter, more flexible armor, fabrics treated with shear- thickening and magnetorheological fluids could have other uses as well. For example, such materials could create bomb blankets that are easy to fold and carry and can still protect bystanders from explosion and shrapnel. Treated jump boots could harden on impact or when activated, protecting paratroopers' boots. Prison guards' uniforms could make extensive use of liquid armor technology, especially since the weapons guards are most likely to encounter are blunt objects and homemade blades.

2.3.3. Carbon nanotubes Carbon nanotube (CNT) [30] is an ideal candidate material for bulletproof vests due to its unique combination of exceptionally high elastic modulus and high yield strain. A Young's modulus of about 1 000 GPa, strength ranging between 13 ÷ 53 GPa, and strain at tensile failure predicted to be as high as ∼16% typically characterize SWCNTs (Single Walled NanoTubes). Assuming that the specific gravity of SWCNT is about 1.4 g/cm3, one can estimate the ballistic performance parameter to range between 2 708 m/s and 4 326 m/s. These values are in agreement with the previously reported value of 3 000 m/s by Alan Windle for the ballistic performance parameter of carbon nanotubes. If one compares these values with those for other fibers suitable for ballistic applications, the enormous potential of CNTs as a candidate material for bullet-proof armor system is quite evident.

Figure 2.21: Specific energy absorption capacity as a function of sonic velocity for selected high performance fibers.

There are three different approaches for utilizing carbon nanotubes to enhance the ballistic performance of a body armor. These are: 1. Incorporation of CNTs into PMCs, metals or ceramics to enhance their hardness or toughness and erosion resistance; 2. Use of neat or composite fibers of CNTs in the form of woven or non-woven fabric, for achieving exceptional ballistic performance; 3. Reinforcing the armor grade fibers like Kevlar, UHMWPE or PBO with CNTs to improve their elastic modulus and energy absorption capacity. These methods are schematically shown in Figure 2.22.

Figure 2.22: Methods of employing carbon nanotubes for ballistic armor applications.

Carbon nanotubes possess very high hardness. In fact, superhard materials synthesized by compressing SWCNTs at 24 GPa exhibit hardness of up to 152 GPa, which is even greater than that of a diamond sample. Therefore, incorporation of CNTs as one of the components in a polymer matrix composite armor tile is likely to deform/erode/fracture the projectile when it is attacked, because of its extreme hardness. Carbon nanotubes, due to their unique combination of high elastic modulus and high strain to failure are capable of elastically storing an extreme amount of energy, which can cause the bullet to bounce off or be deflected. This attribute of carbon nanotubes can also provide the armor improved protection against blunt trauma effects. Based on their computational modeling studies, Mylvaganam and Zhang have shown that body armor comprising six layers of carbon nanotube yarns, each of 100 µm thickness, would have the capability of bouncing off a bullet with a muzzle energy of 320 J.

Figure 2.23: Artist’s representation of a carbon nanotube.

The above-mentioned characteristic of carbon nanotubes has been practically utilized by Block Textiles, Inc., USA. The company has developed a light weight impact deflecting bullet-proof vest comprising directionally aligned single-walled carbon nanotubes in the matrix of an epoxy resin, that is near impervious to bullets fired at close range at all angles of incidence. Moreover, it also exhibits improved impact puncture and penetration resistance, which provides the wearer of the vest enhanced protection against blunt trauma effects. The above armor tiles can be fabricated by curing a mixture of carbon nanotubes in an epoxy resin under a controlled temperature and humidity environment and applying an electric field of sufficient strength to align the SWCNTs. The typical surface topography of the armor tile is shown in the following SEM micrograph, wherein the rope- like structure formed by the unidirectionally aligned single walled carbon nanotubes is quite evident. Researchers from Lockheed Martin Corp., have developed a hybrid composite containing fibrous reinforcement, wherein the polymer matrix is enhanced by the additions of either SWCNTs or MWCNTs (or combination of both). The incorporation of the CNTs in the PMC based armor results in improved ballistic properties and is reflected in significant reduction in the projectile velocity as determined by the V50 ballistic test. The above ballistic material developed is promising for applications in personal body armor, aircraft, ships, and armored vehicles.

Figure 2.24: Carbon nanotubes being spun to form a yarn, CSIRO [31].

Nanocomp Technologies Inc., Concord, N.H., USA has been working with US Army's Natick Soldier Center to develop a new generation lightweight, body armor based on their CNT technology. Their proprietary CVD process is capable of producing large quantities of one-millimeter long CNTs, and CNT-based yarns, sheets and rolls. In April 2009, the company demonstrated that their ~5 mm thick CNT-composite panels can stop a 9 mm bullet in controlled ballistic testing. Their body armor technology has now matured beyond early stage of development and has made considerable progress towards its commercialization. Currently, the hard body armor incorporates a ceramic tile strike face for providing superior ballistic performance while being lightweight. Alumina, silicon carbide and boron carbide are some of the candidate ceramic materials commonly used in body armor. Although these ceramics are very hard, they are also quite brittle and, therefore, hardly able to survive one or two shots before catastrophic fracture of the ceramic tile leading to collateral damage. Consequently, there is a need to improve their multi-hit capability. This could be achieved by enhancing their fracture toughness.

Carbon nanotubes are being considered as a reinforcing material to enhance the mechanical properties of ceramics, particularly by fracture toughness, which is likely to improve their resistance against multiple hits by bullets. Recent studies have shown that incorporation of CNTs in ceramics like alumina and silicon carbide can have a strong influence on the microstructure, fracture mode and mechanical properties. A significant improvement of up to 94% in fracture toughness was observed when 4% vol. of CNTs are added to alumina. Researchers from Military University of Technology, Poland, have conducted numerical modeling investigations to determine the ballistic performance of CNT fiber reinforced 7017 aluminum alloy. Their numerical model analyzed the impact of a sharp nosed projectile on the metal matrix composite plate by performing computer simulations employing finite element methods and clearly showed that the CNT fiber reinforcement plays an important role in determining the overall ballistic resistance of the composite plate.

2.3.4. Spider-silk After decades of trying, scientists may have finally found a way to make body armor out of spider silk [32, 33]. This would mean ultra-lightweight, super-strong, flexible body armor that would provide highly improved protection soldiers and law enforcement officers. Developing lightweight, flexible soft body armor with the higher degree of protection of hard body armor has so far been the impossible dream. Strand-for-strand, researchers in the field know, the drag line of an orb-weaving spider, while weighing far less, can be three times more flexible than Kevlar and five times stronger than steel. Contrary to its size and weight, spider silk is naturally capable of absorbing a huge amount of energy. There are two key components to spider silk fiber: the soft goo gel that is manufactured in the abdomen and the strong solid thread that it has become when it leaves the body. Among the challenges: cracking the genome profile of ideal spider silk; finding a way to synthesize the silk-making protein; and devising a method to mass-manufacture the protein in the volumes necessary. Farming the spiders has not been an option, as spiders do not play nicely with each other -- they show an aggressive and cannibalistic behavior and fail to produce the mass volumes necessary. Tomato plants, crops, bacteria, yeast and goats have gone in and out of fashion as vehicles for converting the spider silk gel into solid thread. Silkworms produce fragile silk, but they have heaps of natural potential as high volume producers capable of spinning approximately a kilometer of silk thread in a 67 few days, with a long history of successful human cultivation. The latest breakthrough was achieved by the University of Wyoming and published in Proceedings of the National Academy of Sciences this month. According to their publication, they have succeeded in genetically modifying silkworms to produce a combination of worm and spider silk that is as strong as spider silk. Arguably, the Holy Grail for Spidey body armor would be cracking the bark spider, reputedly 10 times stronger than Kevlar, and then applying these new silkworm factories. Bark spider silk is the strongest on earth, 100 percent tougher than all other documented silk.

Figure 2.25: Spun and refined spider silk.

3. Unmanned Ground Vehicles

3.1. Historical Background An Unmanned Ground Vehicle (UGV) is a vehicle that operates while in contact with the ground and without an onboard human presence [34]. In the broadest sense, an UGV is any piece of mechanized equipment that moves across the surface of the ground and serves as a means of carrying or transporting something, but explicitly does not carry a human being [35]. UGVs can be used for many applications where it may be inconvenient, dangerous, or impossible to have a human operator present, and they can be classified according to several characteristics, such as the purpose of the development effort, the specific reason for choosing an UGV solution for the particular application (hazardous environment, size limitation), the operating area, the mode of locomotion (wheel, track or legs), the control and navigation techniques employed for determining the vehicle’s path. UGVs’ design may be very variable, but generally they are composed of the following parts [36]: Sensors: Sensor(s) are needed by UGVs in order to perceive their surroundings, permitting controlled movement. The accuracy of the sensors is really important, particularly for UGVs that operate in highly unpredictable environments such as the battle field or fires. Platform: The platform provides locomotion, utility infrastructure and power for the UGV. Control: The level of autonomy and intelligence of the UGV depends largely on its control systems, which range from classic algorithmic control to more sophisticated methods such as hierarchical learning, adaptive control, and neural networks. Human machine interface: The human machine interface depends on how the UGV is controlled. The interface could be a joystick and a monitor control panel in the case of teleoperation, or more desired advanced ones such as speech commands from the commander. Communication: Communication is essential in the case of military UGVs, where both accuracy and secrecy of information exchange are crucial. The communication happens between the humans, involved in the decision making cycle, and the UGV, involved in operations, and possibly between UGVs. This requires a communication link between the human and the vehicle that can vary from radio link to fiber optics. 69

System integration: The choice of system level architecture, configuration, sensors and components provide significant synergy within an UGV system. Well-designed UGV systems will become self-reliant, adaptable and fault tolerant, thereby increasing the level of autonomy.

The first example of UGV is probably the Teletank, developed by the Soviet Union in 1930s and early 1940s, which consists in a series of wireless remotely controlled unmanned tanks [37]. The first combat use was in the Winter War, at the start of World War II. The teletank (TT) is controlled by radio from a control tank (TA) at a distance of 500 ÷ 1 500 meters, the two constituting a telemechanical group. Usually, the control tank, where the operator and the radio transmitter were placed, stayed back as far as possible to still communicate with the teletank, while the latter approached the enemy. The control tank would provide fire support as well as protection for the radio control operator; moreover, if the enemy was successful at seizing the teletank, the control tank crew was instructed to destroy it with its main gun. When not in combat the teletank was driven manually.

Figure 3.1: USSR Teletank.

Teletanks were equipped with DT machine guns, flamethrowers, smoke canisters [37], and sometimes a special 200 ÷ 700 kg time bomb in an armored box, dropped by the tank near the enemy's fortifications and used to destroy heavy fortified bunkers: the time delay of the bomb is at least 15 minutes from hitting the ground allowing the tank to withdraw to a safe distance.

Figure 3.2: Teletank T-18 layout.

Figure 3.3: Teletank T-18 in flamethrower layout.

Teletanks were also designed to be capable of using chemical weapons, although they were not used in combat. Each teletank, depending on its model, was able to recognize sixteen to twenty-four different commands sent via radio on two possible frequencies to avoid interference and jamming.

Figure 3.4: Teletank T-26. 71

Teletanks were built based on T-18, T-26, T-38, BT-5 and BT-7 tanks; they were employed by the Soviet Red Army in the Winter War, and at least two teletank battalions were fielded at the beginning of the Great Patriotic War [37].

During World War II, the British developed a radio control version of their Matilda II infantry tank in 1941. Known as Black Prince, it would have been used for drawing the fire of concealed anti-tank guns, or for demolition missions. Due to the costs of converting the transmission system of the tank to Wilson type gearboxes, an order for 60 tanks was cancelled [38].

Figure 3.5: First prototype A43 Black Prince.

In the same period, the Germans employed the Goliath tracked mine – Leichter Ladungsträger Goliath (SdKfz. 302/303a/303b) – a remote controlled German-engineered demolition vehicle, also known as the beetle tank to the Allies [39, 40]. It was developed by the Wehrmacht, and its different models were able to carry 60 or 100 kg of high explosives. It was intended to be used for multiple purposes, such as destroying tanks, disrupting dense infantry formations, and demolition of buildings and bridges.

Figure 3.6: An SdKfz. 303, the petrol gasoline version of the Goliath. 72

The Goliath was inspired by a miniature French tracked vehicle found after France was defeated in 1940. The result was the SdKfz. 302 (Sonderkraftfahrzeug, “special- purpose vehicle”), called the Leichter Ladungsträger (“light charge carrier”), or Goliath, which carried 60 kilograms (130 pounds) of explosives. The vehicle was steered remotely via a joystick control box. The control box was attached to the Goliath by a triple-strand cable connected to the rear of the vehicle, for transmitting power to the electric driven version. Two of the strands were used to move and steer the Goliath, while the third was used for detonation: it was possible to assign only very simple commands like “left”, “right”, “detonate”, it was not even possible to go on reverse. The Goliath had 650 metres (2 130 feet) of cable; each Goliath was disposable, being intended to be blown up with its target. Early model Goliaths used an electric motor but, as these were costly to make (3 000 Reichsmarks) and difficult to repair in a combat environment, later models (known as the SdKfz. 303) used a simpler, more reliable gasoline engine.

Figure 3.7: Cut away of a gasoline powered Goliath.

Goliaths were used on all fronts where the Wehrmacht fought, beginning in early 1942. They were used principally by specialized Panzer and combat engineer units. Goliaths were employed at Anzio in Italy in April 1944, and against the Polish resistance during the Warsaw Uprising 1944; a few Goliaths were also seen on the beaches of Normandy during D-Day, though most were rendered inoperative due to artillery blasts severing their command cables. A small number of Goliaths were also encountered by 73 allied troops in the Maritime Alps following the landings in southern France in August 1944, with at least one being used successfully against a vehicle of the 509th Parachute Infantry Battalion.

Figure 3.8: Cut away of a SdKfz 303a in detail.

Although a total of 7 564 Goliaths were produced, the single-use weapon was not considered a success due to the high unit cost, low speed (just above 6 miles per hour – 9.7 km/h), poor ground clearance (just 11.4 centimeters), vulnerable command cables and thin armor which failed to protect the remote bomb from any form of antitank weapons.

The first major mobile robot development effort named Shakey [41] was created during the 1960s as a research study for the Defense Advanced Research Projects Agency for Artificial Intelligence (DARPA-AI) to test its obedience with commands, which is different from advanced robots that are autonomous or semi-autonomous: as a matter of fact, while other robots would have to be instructed on each individual step of completing a 74 larger task, Shakey could analyze the command and break it down into basic chunks by itself. Shakey was a wheeled platform that had a TV camera, sensors, and a computer to help guide its navigational tasks of picking up wooden blocks and placing them in certain areas based on commands. It used search techniques to plan “way points” for navigating while avoiding obstacles.

Figure 3.9: Shakey, the first mobile robot that could make decisions about how to move in its surroundings.

Although the problems Shakey faced were simple and only required basic searches, the researchers developed a sophisticated software search algorithm called “A*” that would also work for more complex environments. Today A* is used in applications such as understanding written text, figuring out driving directions, and playing computer games. A planning system called STRIPS (“Stanford Research Institute Problem Solver”) reasoned about complicated goals, like “go to room D and push block 9 over to where doorway 4 is.”

3.2. State of the Art and Future Development There are two specific class of UGVs: Remote-operated and Autonomous. A remote-operated UGV is a vehicle remotely controlled by an human operator. All the actions are determined by the operator supported by either direct visual observation or by the sensors placed on the UGV, like a digital video camera. An example would be a toy remote control car. There are a wide variety of remote-operated UGVs in use today. Predominantly these vehicle are used to replace humans in hazardous situations. Examples are explosives and bomb disabling vehicles: according to press reports, the military has deployed nearly 5 000 robots in Iraq and Afghanistan, starting from up from 150 in 2004 [42]. Soldiers have used them to search caves and buildings for insurgents, detect mines, and ferret out roadside bombs. By the end of 2005, robots reportedly had rendered safe or exploded more than 1 000 ground mines. Actually, this kind of UGV is also employed in Japan in order to repair nuclear reactors that are still emitting too much radiation to warrant a human presence. UGVs are also being developed for peacekeeping operations, ground surveillance, gatekeeper/checkpoint operations, urban street presence, and to enhance police and military raids in urban settings. UGVs can “draw first fire” from insurgents – reducing military and police casualties. Furthermore, UGVs are now being used in rescue and recovery missions. These robots were paramount following 9/11, when searching for survivors at Ground Zero.

An autonomous UGV is essentially an autonomous robot that operates without the need for a human controller. The vehicle uses its sensors to develop some limited understanding of the environment, which is then used by control algorithms to determine the next action to take in the context of a human provided mission goal. This fully eliminates the need for any human to watch over the menial tasks that the UGV is completing.

A fully autonomous robot may have the ability to:  Collect information about the environment, like building maps of building interiors;  Detect objects of interest such as people and vehicles;  Travel between waypoints without human navigation assistance;  Work for extended durations without human intervention;

 Avoid situations that are harmful to people, property or itself, unless those are part of its design specifications;  Disarm, or remove explosives;  Repair itself without outside assistance.

A robot may also be able to learn autonomously. Autonomous learning includes the ability to:  Learn or gain new capabilities without outside assistance;  Adjust strategies based on the surroundings;  Adapt to surroundings without outside assistance;  Develop a sense of ethics regarding mission goals.

Autonomous robots still require regular maintenance, as with all machines. One of the most crucial aspects to consider when developing armed autonomous machines is the distinction between warriors and civilians: this aspect is fundamental nowadays, when combatants often intentionally disguise themselves as civilians to avoid detection. Even if a robot maintained 99% accuracy, the number of civilian lives lost can still be catastrophic. Due to this, it is unlikely that any fully autonomous machines will be sent into battle armed, at least until a satisfactory solution can be developed.

3.2.1. Frontline Robotics Teleoperated UGV The Frontline Robotics Teleoperated UGV (TUGV) is a remote controlled teleoperated vehicle developed to address the threats from large explosives and Vehicle Borne IEDs (VBIEDs) [43]. It is characterized by one of the largest towing capacity and longest run-time of any counter VBIED vehicle platform, providing first-responders a multi-purpose vehicle capable of performing under the most challenging conditions imaginable: as a matter of fact, Robots currently used for VBIED disruption are severely limited in their capabilities since these are typically EOD platforms that were not originally designed for disruption of large improvised explosive devices. EOD platforms are small, lightweight and employ batteries for power; however the mission requirements for VBIED disruption require disruptors that weigh 150 kg to 700 kg be towed long distances to the VBIED or other explosive threat. A battery operated EOD robot does not have the power, load or towing capacity to meet these requirements.

Figure 3.10: Tele-operated UGV – Frontline Robotics.

TUGV main feature is a towing capacity of 1 750 pounds (794 kg), in order to pull one of the largest VBIED “battle wagons”, moreover it can carry a 1 000 pounds (454 kg) payload capacity in the rear cargo bed and a 100 pounds (45.4 kg) payload capacity on the front deck, respectively to transport mission-critical equipment to remote sites and optional CBRNe sensors and equipment. The long range operation is possible thanks to a wireless communication system, by which the data taken from the wide-angle driving cameras and from the CBRNe sensors are send to the remote operator.

3.2.2. Battlefield Extraction-Assist Robot The Battlefield Extraction-Assist Robot (BEAR) is a military robot developed by Vecna Technologies that will be used for the extraction of wounded soldiers from the battlefield with no risk to human life. The BEAR is a six feet (1.8 m) tall humanoid robot with advanced technology and features that make the robot effective and intelligent. Vecna's roboticists designed the robot with a teddy bear face to provide those being rescued comfort and reassurance. The humanoid robot uses a powerful hydraulics system to carry humans and other heavy objects over long distances and rough terrain such as stairs. The BEAR is remotely controlled by an operator thanks to cameras and microphone placed on it.

Figure 3.11: Battlefield Extraction-Assist Robot – BEAR.

The initial versions of the BEAR were remotely controlled by a human operator who was able to see and hear through the robot's sensors. Later, developments to the BEAR’s AI have given the robot the ability to process higher lever commands given by an operator such as “go to this location” or “pick up that box” [44]; however, if the robot is unable to execute the operator’s command, it is programmed to ask the operator for assistance to complete the task [45]. Another way to remotely control the BEAR is via a device known as the iGlove, that is a motion-capture glove developed by AnthroTronix which allows the operator to make a simple hand gesture to command the robot. Another remote control, developed by AnthroTronix too, is the Mounted Force Controller, that is a specific rifle grip mounted on an M-4 carbine to let soldiers to command the BEAR without putting down their weapon [46].

Figure 3.12: BEAR diagram.

The BEAR is powered through a hydraulic actuator which gives the robot the ability to lift 520 pounds (236 kg), while the tracked legs are electronically powered by a battery pack that allow an autonomy up to an hour. The bear is equipped with infrared, night vision, and optical cameras as well as a microphone. Further study will include also a touch and pressure sensors on the BEAR’s hands, and chemical and biological agent detection sensors. Moreover, Dynamic Balance Behavior (DBB) technology has been implemented in the BEAR in order to give the robot the ability to maintain balance in any position even while carrying heavy objects.

Figure 3.13: BEAR in action. 80

Figure 3.14: Detail of the 3 fingers, 6 degree of freedom BEAR’s arm.

The main purpose of the BEAR is to carry a wounded soldier far away from a hazardous environment to a place where a medic can assess their injuries safely without risk to the medic's life. The robot has been designed slim enough to fit through doors and the BEAR's tracks enable it to climb stairs. Other application of the BEAR include:  Search & rescue;  Transporting supplies;  Clearing obstacles;  Lifting heavy objects;  Handling hazardous materials;  Reconnaissance;  Inspecting for mines and IEDs.

3.2.3. Multi-Mission Unmanned Ground Vehicle The Multi-Mission Unmanned Ground Vehicle, previously known as Multifunction Utility/Logistics Equipment vehicle (MULE), or as Robotic Infantry Support System (RISS), was an unmanned platform developed by Lockheed Martin Missiles and Fire Control [47] and by the General Dynamics Eagle Enterprise [48] for the United States Army's, whose development has been cancelled in July 2011 [49]. It provided transport of equipment 81 and/or supplies in support of dismounted maneuver force. It was also be capable of being armed in the role of support to dismounted infantry in the close assault. There were three variants of the MULE, according to the specific task to be accomplished that is: 1. Transport; 2. Air assault; 3. Countermine use.

Figure 3.15: Multi-Mission Unmanned Ground Vehicle in action.

The main purpose of the RISS was to reduce the soldier's load and to carry supplementary supplies such as water and ammunition: it's basically a mini load-carriage system available to the soldiers when needed, which allows lightening the load for the individual soldier, while taking the supplies available at the right time. General Dynamics envisions additional uses for the RISS that may include reconnaissance and surveillance or medical and personnel transport. The 15-foot (4.6 m) long, six-foot (1.8 m) wide vehicle would be capable of carrying a payload of up to 2 000 pounds of weapons, supplies or personnel.

Figure 3.16: MULE.

Anything else that is mission-essential but not built in to the individual soldier system would be carried on a “robotic mule”. The MULE would have assisted with not only taking some of the load carriage off the individual soldier, but it would also provide a host of other functions, such as the water generation and/or water purification; moreover it acted as a weapons platform, it had day and night thermal, infrared and forward-looking imaging systems inside the nose, as well as chemical-biological sensors.

Figure 3.16: MULE, artist’s conception.

Another aspect of the MULE was the possibility to communicate with unmanned aerial vehicles to give the squad members a true 360-degree image of the battlefield. The MULE may incorporate mechanisms, such as a robot arm/hand, to facilitate transloading equipment or supplies on and off the vehicle; it would provide semi- autonomous navigation, possibly including automated transloading of selected supplies.

3.2.4. TerraMax TerraMax is the trademark for unmanned ground vehicle technology developed by Oshkosh Corporation. The original TerraMax vehicle was a 6×6 autonomous MTVR-based tactical cargo hauler entered in the 2004 and 2005 DARPA Grand Challenge by Oshkosh Corporation, University of Parma's Artificial Vision and Intelligent Systems Laboratory and Rockwell Collins (collectively known as Team TerraMax). A 4×4 variant was subsequently developed for and entered in the 2007 DARPA Urban Challenge. Since then, Oshkosh has continued developing the technology for the United States Department of Defense. The TerraMax is now supplied to the U.S. and British military; actually it is employed in reconnaissance missions and freight transport in high-risk areas so freeing soldiers from possible attacks or ambushes [50].

Figure 3.17: Vehicle equipped with TerraMax UGV.

The TerraMax UGV is a vehicle kit system that advances perception, localization and motion planning to protect warfighters from IED threats and increase performance in autonomous missions. Such a kit can be placed on any tactical wheeled vehicle and it is capable of supervised autonomous navigation in either a lead or follow role. Its multi- sensor system combines with novel registration techniques to provide accurate positioning estimates without needing to rely on continuous tracking through a lead vehicle or in GPS denied environments [51]. The vehicles equipped with TerraMax are capable of navigation to the objective independently. This not only facilitates tight convoy formation, but also enables the composition of the convoy to change as demanded by traffic conditions, road blockages or other obstructive situations. The system is fully integrated onto the vehicle to minimize system vulnerability while enabling Advanced Driver Assist Systems such as Electronic Stability Control, Collision Mitigation Braking and Adaptive Cruise Control. This provides for more streamlined installation, safer operation and more advanced autonomous control. Terramax capability has been proven in Series 19 of BBC Television series Top Gear [52], where it was featured against presenter James May in the Range Rover in an off-road challenge in the Nevada Automotive Test Center, Nevada, USA. The TerraMax demonstrated its capability to “see” the surrounding area thanks to its sensors. Moreover, it featured also the capability to remotely deflate the tires to have a better grip in difficult ground conditions.

3.2.5. Legged Squad Support System The Legged Squad Support System (LS3) is a rough-terrain robot funded by DARPA and the US Marine Corps designed to go anywhere marines and soldiers go on foot, helping carry their load. Each LS3 carries up to 400 pounds (181 kg) of gear and enough fuel for a 20-mile (32 km) mission lasting 24 hours. LS3 automatically follows its leader using computer vision, without the need of a dedicated driver. It also travels to designated locations using terrain sensing and GPS. The initial contract for the Legged Squad Support System was awarded to Boston Dynamics on December 3, 2009; the contract schedule called for an operational demonstration of two units with troops in 2012. DARPA, which has continued to support the program, carried out the first outdoor exercise on the latest variation of the LS3 in February 2012, with it successfully demonstrating its full capabilities during a planned hike encompassing tough terrain.

Figure 3.18: LS3 in close formation.

Following its initial success, an 18-month plan was unveiled, which saw DARPA complete the overall development of the system and refine its key capabilities, due to start in summer 2012. On September 10, 2012, two LS3 prototypes were demonstrated in an outdoor test. The LS3 prototypes completed trotting and jogging mobility runs, perception visualization demonstrations, and a soldier-bounded autonomy demonstrations. They were roughly “10 times quieter” than the original platform. Other improvements included a 1 to 3 mph (1.6 ÷ 4.8 km/h) walk and trot over rough, rocky terrain, an easy transition to a 5 mph (8 km/h) jog, and a 7 mph (11.3 km/h) run over flat surfaces. In early December 2012, the LS3 performed walks through woods in Fort Pickett, Virginia. These tests were with a human controller giving voice commands to the robot to give it orders. Giving voice commands is seen as a more efficient way of controlling the LS3, because a soldier would be too preoccupied with a joystick and computer screens to focus on a mission. There are currently ten commands that the system can understand. Saying “engine on” activated it, and saying “follow tight” made it walk on the same path as the controller. Saying “follow corridor” made the LS3 generate the path most efficient for itself to follow the human operator. Others include basic orders like “stop” and “engine off”. Continued work is being made to make the LS3 more mobile, like traversing a deep snow- 86 covered hill, or avoiding gunfire and bombs on the battlefield. DARPA intends to supply a Marine company with an LS3 by 2014 [54].

Figure 3.19: LS3 in load position.

From 7-10 October 2013, the LS3 took part in testing, along with other systems, at Fort Benning, Georgia as part of the U.S. Army's Squad Multipurpose Equipment Transport (S-MET) program. The program objective is to find an unmanned robotic platform to transport soldier equipment and charge batteries for their electronic gear. Requirements for the vehicle are to carry 1 000 pounds (450 kg) of gear, equal to the amount a nine-man infantry squad would need on a 72-hour mission. Cubic volume is seen as more of a problem for load-carrying unmanned vehicles, as their center of gravity changes when more gear has to be stacked. It has to travel 4 km/h (2.5 mph) for eight hour marches and speed up in bursts of up to 38 km/h (24 mph) for 200 meters. The proposed S-MET vehicle needs to traverse forward and backward on slopes of up to 30 percent and descending on slopes of 60 percent.

4. Powered Exoskeleton

4.1. Historical Background The idea of covering the warriors’ body with armor for protection dates back to ancient times, however the idea of a body with mechanical muscles appeared in relative recent times in history, especially after the advent of steam power. Edward Sylvester Ellis, in 1868, wrote about an inventor, the teenage dwarf Johnny Brainerd, that constructed a nonsentient automaton called the Steam Man [55], whose adventures where published in the dime novel “The Steam Man of the Prairies”. The book narrated on a man that shall go by steam, in the shape of a giant humanoid, that tow its creator behind it in a cart at speeds of 60 miles an hour (96.5 kilometers per hour), while it chased buffaloes and terrorized Indians. Here the description of the Steam Man according to the novel:

Perhaps at this point a description of the singular mechanism should be given. It was about ten feet in hight, measuring to the top of the 'stove-pipe hat,' which was fashioned after the common order of felt coverings, with a broad brim, all painted a shiny black. The face was made of iron, painted a black color, with a pair of fearful eves, and a tremendous grinning mouth. A whistle-like contrivance was trade to answer for the nose. The steam chest proper and boiler, were where the chest in a human being is generally supposed to be, extending also into a large knapsack arrangement over the shoulders and back. A pair of arms, like projections, held the shafts, and the broad flat feet were covered with sharp spikes, as though he were the monarch of base-ball players. The legs were quite long, and the step was natural, except when running, at which time, the bolt uprightness in the figure showed different from a human being. In the knapsack were the valves, by which the steam or water was examined. In front was a painted imitation of a vest, in which a door opened to receive the fuel, which, together with the water, was carried in the wagon, a pipe running along the shaft and connecting with the boiler. The lines which the driver held controlled the course of the steam man; thus, by pulling the strap on the right, a deflection was caused which turned it in that direction, and the same acted on the other side. A small rod, which ran along the right shaft, let out or shut off the steam, as was desired, while a cord, running along the left, controlled the whistle at the nose.

The legs of this extraordinary mechanism were fully a yard apart, so as to avoid the danger of its upsetting, and at the same time, there was given more room for the play of the delicate machinery within. Long, sharp, spike-like projections adorned those toes of the immense feet, so that there was little danger of its slipping, while the length of the legs showed that, under favorable circumstances, the steam man must be capable of very great speed [56].

Figure 4.1: Cover of “The Steam Man of the Prairies”.

In the last decade of XIX century, Nicholas Yagn, of St. Petersburg, Russia, patented an assisted walking device called Apparatus for facilitating walking and running.

Figure 4.2: US Patent 406 328 – Apparatus for facilitating walking and running.

The earlier version used a giant bow spring, and in particular it consisted of a spring- support for the body and adapted to be secured to the legs and operating to relieve the latter of the weight of the body, or such weight and an additional weight or burden carried by the body […]. The invention further consists in the combination, with the spring-support for the body, of a like support for the legs to assist the latter in carrying the weight of the body and in overcoming the inertia thereof [57]. The final version of the apparatus, called Apparatus for facilitating walking, running and jumping, used compressed gas bags to store the energy and it is a perfect example of a passive and human-powered exoskeleton. This invention consisted in a compressed-fluid accumulator adapted to be applied to the feet and to support and take up the entire weight of the body, or approximately so, as well as the power due to the momentum when the body is in motion 5 (see Figure 4.3) also, in the combination, with the accumulator, of a storage-reservoir adapted to be carried on the person, in which a fluid is stored under pressure [58].

Figure 4.3: US Patent 440 684 – Apparatus for facilitating walking, running and jumping.

However we have to wait the 1917 to have the first example of a device that use energy generated apart from the user, when the US inventor Leslie C. Kelley developed the Pedomotor [59]. The idea is to facilitate the operation of pedestrianism or running operation, providing relief of muscles utilized during the running operation, and to increase the speed of the person. Although any type of motive power can be applied, Kelley describes a small steam-engine to be worn on the persons back. Artificial ligaments parallel the main muscle ligaments and are directly connected to the motive power source.

Figure 4.4: US Patent 1 308 675 – Pedomotor.

In the mid-1960s, Cornell University engineer Neil Mizen had developed a 35 pound (15.8 kilogram) wearable frame exoskeleton, called the man amplifier. The project was never completed, but the intention was to put hydraulic motors on the suit’s joints enabling any normal person to lift 1 000 pounds (453.6 kilograms) with each hand. The motor, a 20 horsepower gasoline engine plus fuel tank, should have been installed on the back of the wearer, and the final suit should have had a weight of about 400 pound (181 kg) [60].

Figure 4.5: Popular Science page on Man Amplifier.

By 1961, two years before the fictional Iron Man was created by Marvel Comics, the Pentagon had actually invited proposals for real-life wearable robots. In an article published by The Spokesman Review, the soldier of a distant future is described as an human tank equipped with power steering and power breakes. […] The “servo-soldier” […] will wear a special suit which will have its own engine enabling him to run faster, stop quicker and lift bigger loads that ordinary mortals. What’s more, he will be immune to germ warfare, poison gas and the heat and radiation from nuclear blasts [61]. In addition to this Cold War propaganda, in the 1960s the United States military had indeed designed, in collaboration with General Electric, the first true exoskeleton in the sense of being a mobile machine integrated with human movements, inspired by Neil Mizen work on the man amplifier. The suit was named Hardiman, and should have been word as an outer mechanical garment; moreover it should have been powered by hydraulics and electricity to dramatically amplify the wearer’s strength and endurance, by a factor of approximately 25 to one, so it was made lifting 250 pounds (110 kg) feel like lifting 10 pounds (4.5 kg). A feature dubbed force feedback enabled the wearer to feel the forces

93 and objects being manipulated, in order to provide the operator with sensitive control of the structure and act as a safeguard against the application of excessive force.

Figure 4.6: Hardiman.

The device was intended to be enable to lift and handle loads in excess of 1 000 pounds (454 kg) and to mimic the movements of its wearer, presenting a literal union of man and machine, combining the machine’s strength and endurance with the human’s flexibility, intellect and versatility [62]. While the general idea sounded promising, the actual Hardiman had major limitations [62]. It was impractical due to its 1 500 pound (680 kg) weight, and its slow walking speed (2.5 feet/s – 0.76 m/s) further limited practical use. Moreover, it was intended as a slave-master system: the operator is in a master suit which is in turn inside the slave suit which responds to the master and takes care of the work load. However, this multiple physical layer type of operation may work fine, but takes longer response time than a single physical layer, that can be a trouble if the goal is physical enhancement. While the single components of Hardiman were tested with some results, any attempt to use the full exoskeleton resulted in a violent uncontrolled motion: for this reason it was

94 never tested with a human inside. Further research was not focused on the full exoskeleton, but was concentrated only on one arm. Although it could lift its specified load of 750 pounds (340 kg), it weighed about 750 kg, more than twice the liftable load. Without getting all the components to work together the practical uses for the Hardiman project were limited, and was too heavy and bulky to be of military use [63].

Figure 4.7: Hardiman prototype arm system.

In the next decade further studies on this topic weren’t realized, until Jeffrey Moore, an engineer at Los Alamos National Laboratory, dusted off the concept in 1985. Moore’s proposal was an exoskeleton, called Pitman, consisting of a powered suit of armor for infantrymen capable of carrying 300 pounds (136 kg) of equipment. The operator is housed in a 500 pounds (227 kg) fiberglass, polymer/ceramic composite armor called Body Armor, Powered (BAP), that consists of six layers, as shown in Figure 4.8 [64]:  Impregnated antibacterial polypropylene;  Closed-cell foam laced with heating/cooling tubing; 95

 Sealed, impermeable "condom" layer;  Nitrogen-filled polyurethane bubble sensors;  Energy absorbing closed-cell foam;  Laminated, composite armor.

Figure 4.8: Pitman.

However, the Defense Department was not interested in this proposal: the main reason is probably that Pitman was too futuristic even for the Pentagon. Moore’s concept was to control the exoskeleton via a network of brain-scanning sensors in the helmet that would have measured the shifting magnetic fields generated by the brain during movement. For this reasons, Pitman stayed on the drawing board.

In 1986 Monty Reed, a US Army Ranger who had his ankle and back broken during a fall in a parachute accident, created an exoskeleton prototype called Lifesuit [65, 66]. The idea of the exoskeleton came from Hardiman and from his reading of Starship Troopers by Robert Heinlein, in particular from the description of Mobile Infantry Power Suits, the powered exoskeletons employed in the novel.

Figure 4.9: Lifesuit 2.

In 2000, Reed started a non-profit organization called They shall walk, aimed to help people with motor disability, and in 2001 the first prototype, LIFESUIT 1, was completed. These firsts prototypes where simple supports barely operating, however some improvement came indeed from LS6, built in 2003, which was able to record and play back a human gait. In 2005, Monty Reed set the Land Speed Distance Record for walking in robot suits when, during the foot race known as the Saint Patrick’s Day Dash, he and his LS12 were able to complete the 3-mile race in 90 minutes. 97

Actually, LIFESUIT 14 can walk one mile with a full charge, lifting 203 pounds (92 kg), while LIFESUIT 16 will be wear under clothes, and will use nanotechnology developed at University of Washington. Moreover, its weigh will be of only 46 pounds (21 kg), plus the 40-pound (18 kg) scuba tank of air that powers it [67].

Figure 4.10: Lifesuit 12.

In January 2007, Newsweek magazine reported that the Pentagon is interested in the findings of nanotechnologist Ray Baughman from the University of Texas. Baughman’s study are focusing on Electroactive Polymers, EAPs, which intended to increase the strength-to-weight ratio of movement systems in military powered armor. EAPs are polymers that exhibit a change in size or shape when subjected to an electric field: typically, EAPs are able to have a large amount of deformation while sustaining large forces: in 1990s it has been demonstrated that some EAPs are capable of a strain up to 380%, which makes them ideal in the development of artificial muscles; as a matter of facts, an EAP is often referred to as an artificial muscle. An electrical voltage, obtained from a fuel cell, can be applied to EAPs, making them contract. In such a way a mini-muscles, a hundred of times stronger than human muscle tissue, is obtained; this muscles can be woven into a fabric that would contract when heated and would go back to its original shape when cooled [68].

Powered exoskeleton seen so far in this work clearly show deficiencies that does not make them suitable for military use; nevertheless this deficiencies are certainly not to be attributed to a lack of ideas or imagination of their makers, but rather to limitations of technology: the computational power, inadequate to have a suit responding to wearer’s command and movements; the battery pack, too big and heavy to be portable; the actuators, too weak and bulky to imitate a human body. In the next section, the progress made in solving those issue will be analyzed. 98

4.2. State of the Art and Future Development The recent years have seen an increase of the technology, in the form of more smaller and versatile sensors, fasters microprocessors, and more performant actuator as seen in the middle of the XX century: this improvement opens the door to a more reliable design of wearable exoskeleton. Actually, several project exist in order to build a wearable exoskeleton that allows the wearer to improve his own performance, and that can be adopted by the military in war operation, or by people affected by mobility disease, allowing them to overcome their motoric dysfunction. In the following paragraph, an in- depth analysis of the more important existing exoskeleton is presented.

4.2.1. XOS In 2000s the Defense Advanced Research Project Agency (DARPA), the agency of the United States Department of Defense responsible for the development of new technologies for use by the military, started a seven-years, $75-million project called Exoskeletons for Human Performance Augmentation. DARPA’s purpose was to design a suit that would have let the average soldier lug hundreds of pounds and hike for days without fatigue, handle weapons that normally require two people, jump higher, and whisk the injured off the battlefield by tossing one or two men on his back. Moreover the suit would have an armor capable to protect the wearer from enemy fire. However this idea sounds unrealistic to some of the experts of DARPA itselfs: “Half the people I talked to believed, almost as if it was a religious thing, and about half thought it was a complete waste of money, time and resources”, says Cornell University engineer Ephrahim Garcia, who led the DARPA program in its early stages [69], adding that “It was a huge challenge”. Nevertheless building an efficient exoskeleton would be a big challenge: it would need a portable power unit capable of supply energy for at least a full day, small and powerful actuators acting like artificial muscle, sensors to read the forces applied on the suit, and an efficient control system capable to perfectly and instantly coordinate exoskeleton actions to the ones of its wearer: even the slightest lag would create a drag- like effect and make the operator feel as if he were moving through water. Finally it needs to be fast. The solution came from a man, Steve Jacobsen, who spent his past 35 years in robotic branch, whose work included among other the 80-ton robotic dinosaur seen in Jurassik Park and the mechanized fountains of the Bellagio casino in Las Vegas. Stephen C. Jacobsen, University of Utah engineering professor, founded a company called Sarcos

99 in 1983, operating principally as a bioengineering research institution. The company evolved, in 1987, into Sarcos Research Corp. and it was focused on creating and commercializing projects developed through the Utah's Center for Engineering Design that Jacobsen had founded in 1973. In 2000, Sarcos applied for DARPA proposal to develop a design for a wearable powered exoskeleton suitable for military applications. One of the biggest issue in the design of a powered exoskeleton, as highlighted also in DARPA proposal, lie in the interface between robot and operator: Jacobsen overcome this issue asking help to Jon Price, the company’s staff photographer, and his daughter. Jacobsen prepared a little test, where Price played the part of the exoskeleton, and his daughter the one of the pilot: she stepped up on her father’s feet, with her toes atop his ones, turning her back to him. Then they held hands balancing themselves and she began to walk: Price had just to indulge his daughter’s movement, keeping his feet directly beneath hers. After just a few minutes their where moving synchronously: the daughter was taking all the high-level decisions (like movement direction and speed) and Price was just mirroring her step by step. This demonstration proved that an intelligent machine can interact with a pilot, interpreting his movements and reacting to them accordingly, by the means of just a few points of contact, as in this case are the feet and the hands. Jacobsen and his group then designed compact actuators, built improved force sensors, invented more-efficient hydraulic valves, and even machined the robot's aluminum feet. According to Obusek, one of the pilot of XOS, “A human will fatigue fairly quickly even with very little resistance”: the purpose is to create a mechanism that reduce that resistance to almost zero. In order to accomplish that, the XOS has been designed as a human limb: the movement that are performed by human’s muscle fibers and tendons are simulated by actuators and cables. The operator’s movement are read by XOS’ sensors, than the data are sent to a computer, which calculates how to move the exoskeleton to mimic its wearer movements minimizing the strain on the user. This directives are sent to a series of valves that control the flow of high-pressure hydraulic fluid to cylinder actuators in the joints. The fluid moves the cylinders, which move the cables attached to them, acting as tendons and pulling on the robotic limbs. The XOS has 30 actuators, each controlling a different joint.

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Figure 4.11: XOS.

This control system has been verified during a test, in which the demo pilot Jameson tried to perform a workout without increasing his heart rate. Sensors were applied in each of his hand-grip, registering the force applied: without the exoskeleton’s help, the sensors would have shown that he was trying to pull down about 100 pounds (45 kg) in each hand, but the goal is to get the force read by the sensors as close to zero as possible; in such a way the work is performed by the XOS and not by the pilot. According to Jacobsen: “The XOS carries itself, and [Jameson] carries himself”.

Figure 4.12: XOS joints.

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Sensors have been applied also on the suit’s feet and back and the data collected, together with those collected by the hand-grip, are sent to a central computer hundreds or, for some sensors, several thousand times per second: those data are used to solve the set of equations that governs the motion and position of the exoskeleton’s legs, arms and back; in such a way, the system realize what Jameson is going to do and what artificial muscle to move in order to mimic him. In this specific case, the suit understand that he wants to bring his hands down, so the system instructs the robotic arms to move before Jameson exerts any significant force, letting him never feel strain. When he steps out of the XOS after a round on the weight machine, he's not even out of breath.

Figure 4.13: Exoskeleton test pilot Rex Jameson greets XOS maker Steve Jacobsen.

In 2002 the first XOS suit was built. This model didn’t have power, but its purpose was to prove that the exoskeleton was able to move like his wearer do, and consequently 102 that every joint was in the right place and the range of motion was correct. In order to do that, some simple actions were tried, like kicking a soccer ball, running, or climbing into the tight cab of a bulldozer. The further step was to provide mechanical muscles to the suit: this issue has been overcame thanks to hydraulically driven actuators. This was not an easy task because every joint have the need to open and close with the proper speed and power, moreover, a purely hydraulic system would waste to much energy to maintain the fluid pressure in the valves: for such a reason Sarcos redesigned the valves that control the flow of the fluid to be more of an on-demand system, so they consume power only when the suit moves, as an electrically driven actuator would. The last version, the XOS 2, is composed by a tank containing a 24-hour supply of fuel, an engine that drives hydraulic fluid via high pressure lines to servo valves on each joint. According to John Main, chief of DARPA’s exoskeleton program, running an internal combustion engine with the power of a scooter will be “smelly and loud”, and the exoskeleton won’t be allowed indoors by the US Occupational Health and Safety Administration: “The OSHA won’t let it run inside a building because basically it’s a vehicle” says Main [70].

Figure 4.14: XOS 2 during a push-up test demo at the Raytheon Sarcos research lab in Salt Lake City, Utah.

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XOS suit hadn’t hit all the point in DARPA program: it doesn’t let a soldier to run faster or make him immune to gunfire. However Sarcos’ idea was closest to DARPA initial vision then the ones of the other 14 teams that participated in the project (Oak Ridge National Laboratory and the University of California at Barkeley among others), and actually it is the only full exoskeleton the military has moved into the further development stage, taking a $10-milion grant [71-73].

4.2.2. Human Universal Load Carrier The Human Universal Load Carrier, HULC, is a powered exoskeleton developed by Professor Homayoon Kazerooni and his team at Ekso Bionics. Ekso Bionics, originally known as Berkeley Bionics, was founded in Berkeley, California, in 2005 [74]. It’s research fields are focused on robotic exoskeletons to augment human strength, endurance and mobility. In addition to HULC, Ekso Bionics developed other exoskeleton device to augment soldiers’ abilities and help disabled people to walk: BLEEX (Berkeley Lower Extremity EXoskeleton): The Berkeley Lower Extremity Exoskeleton, commonly abbreviated BLEEX, is an intelligent, bionic exoskeleton system that provided soldiers, disaster relief workers, wildfire fighters, and other emergency personnel the ability to carry major loads such as food, rescue equipment, first-aid supplies, communications gear and weaponry with minimal effort over any type of terrain for extended periods of time. The vision for the device is that it will provide a versatile transport platform for mission-critical equipment [75]. BLEEX is composed by a set of modified combat boots, attached to metal braces placed on the sides of the legs, and connected to a vest and a backpack. The system operate with the assistance of a Pentium 5 equivalent processor and allow to carry about 70 pounds (32 kg) of load feeling like (2 kg), distributing the remaining load to the mechanical legs. The Bleex 2 should be able to carry up to 150 pounds (68 kg) walking at a speed of 4 miles per hour (6 km/h) [76].

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Figure 4.15: BLEEX.

ExoHiker: ExoHiker was completed in 2005, and it is designed to help hikers carry heavy loads on their back over extended periods of time. It is composed by two artificial legs connected to the back and to the shoes, and it can be strapped on to the body of rambler between 5 feet 4 inches (1.63 m) and 6 feet 2 inches (1.88 m) in height, like a wearable robot; its total weight is 31 pounds (14 kg) including power unit, batteries and on- board computer, and it allow to carry up to 150 pounds (68 kg) while the wearer feels no load, operating noiseless at an average speed of 2.5 mph (4 km/h) for 42 miles (68 km) with just one 80 Watt-hour lithium polymer battery weighing 1.2 pounds (0.5 kg); the

105 mission time can be unlimited with a small solar panel. The exoskeleton is controlled with an handheld LCD display [77].

Figure 4.16: ExoHiker.

ExoClimber: ExoClimber is an enhancement of ExoHiker that allows the wearer the rapid ascend of stairs and climb steep slopes, providing the same long term load carrying capability of ExoHiker. It weighs 50 pounds (23 kg) including power unit and on-board computer, and for each pound of lithium polymer battery, can assist a climber to ascend 600 feet (183 m) vertically with a 150-pound (68 kg) load having the wearer feel no load [78].

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Figure 4.17: ExoClimber.

Ekso/eLEGS: The Exoskeleton Lower Extremity Gait System, eLEGS, is an hydraulic powered exoskeleton that allows paraplegics to stand and walk with the aid of crutches or a walker. The control system interprets the intend of the wearer by means of force and motion sensors, using those information to move appropriately. Moreover, users can easily put on and take off the device by themselves as well as walk, turn, sit down, and stand up unaided [79].

Figure 4.18: eLEGS in action.

In 2011 eLEGS was renamed Ekso. Ekso weighs 45 pounds (20 kg), has a maximum speed of 2 mph (3.2 km/h) and a battery life of 6 hours. It can be wear by users weighing up to 220 pounds (100 kg), who are between 5 feet 2 inch (1.57 m) and 6 feet 4 inch (1.93 m) tall and that can transfer themselves from a wheelchair to the chair where Ekso is placed. It allows the user to walk in a straight line, stand from a sitting position, stand for an extended period of time, and sit down from a standing position. 107

Ekso has been selected as #2 of the 10 Most Significant Gadgets of 2010 by WIRED magazine; it is currently undergoing further development and clinical trials in rehabilitation centers. It should become lighter and more adaptable, and by 2013 should be available for private use at a cost of about $100 000 [80].

Figure 4.19: eLEGS.

Hydraulic Human Power Extender: The Hydraulic Human Power Extender is a six- degree-of-freedom tool designed for loading and unloading aircraft. The carrying capability of the Power Extender is 500 pounds (227 kg), and its gripper jaws open up to 30 inch (76.2 cm). A set of piezoelectric force sensors is located between the wearer and machine, 108 and another one is located between the machine and the load: the first set read the force from the user, while the second one the force reflection in the machine. Three on-board microcomputers control the six axes of the extender. In its simplest behavior, when a worker uses the Hydraulic Human Power Extender to move a load, the extender transfers to her/his arms, as natural feedback, a scaled-down value of the load’s actual weight. The wearer still “feels” the load’s weight, but what he/she feels is less than what he/she would feel without the extender [81, 82].

Figure 4.20: Hydraulic Human Power Extender.

Electric Human Power Extender: The Electric Human Power Extender is a device intended to reduce the risk of low back injuries due to repetitive lifting in warehouse workers. It is composed by an electric extender, composed of two arms and two legs, designed and built for maneuvering boxes. During maneuvering large, rigid, and bulky objects, the device will let the wearer feel the forces as if they were the forces of maneuvering a light, single-point mass. This power extender not only can mask unwanted forces on the wearer, as in the last example, but also can be programmed to follow a particular trajectory regardless of the exact direction in which the wearer manipulates the extender [83, 84].

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Figure 4.21: Electric Human Power Extender.

In January 2009, Lockheed Martin entered into an exclusive licensing agreement with Ekso Bionics (formerly Berkeley Bionics), in order to design a wearable exoskeleton that can allow soldiers in combat operations to carry a load of up to 200 pounds (90 kg) at a speed of 10 miles per hours (16 km/h) for an extended time. Moreover, this wearable exoskeleton, HULC, is the first energetically-autonomous, orthotic, lower extremity exoskeleton, and it allows the wearer to carry the load over any sort of terrain for an extended period of time without undue effort. The control algorithm ensures that the exoskeleton moves in concert with the pilot with minimal interaction force between the two. The control scheme needs no direct measurements from the human or from the human-machine interface like sensors between them. The controller, based on measurements from the exoskeleton only, estimates how to move so that the wearer feels very few forces. This novel control scheme

110 is quite elaborate, but it is an effective way to create locomotion when the area of contact between the wearer and the machine is unpredictable. The innovation respect other exoskeleton systems is related to the power supply: HULC is not tethered to a power generator like XOS 2, but its hydraulic architecture is efficient highly enough to run on batteries. Lockheed Martin has announced that the Protonex Technology Corporation has been selected to develop power supply concepts that will enable the HULC to extend the mission time up to 74+ hour [85]. Another advantage of the HULC system is that it can be removed and packed-up in 30 seconds: soldiers just have to stretch out a leg and step into foot beds underneath the boot. Straps then wrap around the thighs, waist and shoulders. Sensors in the foot pads relay information to the onboard microcomputer that moves the hydraulic system to amplify the wearer's movement. The flexibility of the system allows soldiers to run, walk, kneel, crawl, and even go into low squats. The modular components of the system can be swapped when the warfighter is in danger and needs greater mobility to escape from the enemy [86].

4.2.3. Hybrid Assistive Limb Near the end of the decade, the Robot suit HAL was developed by a Japanese company called Cyberdyne. Cyberdyne Inc. was established in June 2004, in order to disseminate the research result of Professor Yoshiyuki Sankai of the University of Tsukuba for the benefit of public [87], in order to materialize his idea to utilize Robot Suit HAL for the benefits of humankind in the field of medicine, caregiving, welfare, labor, heavy works, entertainment and so on. The name Cyberdyne is the same of the fictional company that produced robots in the Terminator film series, however this is not an intentionally reference but the name choice came from the merging of the new academic field of Cybernics, a new domain of interdisciplinary research centered on cybernetics, mechatronics, and informatics [88], advocated by Prof. Sankai, and the suffix –dyne, referring to power [89]. The Hybrid Assistive Limb is a power exoskeleton designed to support and expand the physical capabilities of its users, and it is in particular focused upon people with physical disabilities. There are two primary versions of the system: HAL 3, which is only provided of leg function, and HAL 5, which is a full-body exoskeleton for the arms, legs, and torso which Cyberdyne claims augments body movement and increases user strength by up to ten times. 111

Figure 4.22: HAL 5.

As of February 2013, Cyberdyne has leased 330 HAL suits to 150 facilities across Japan, and in August 2013 HAL has been given an European Community certification that should allow it to be distributed in Europe as the world first medical treatment robot [90].

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Figure 4.23: HAL 3.

In order to move, the HAL exoskeleton does not need human operator's muscle contractions, but it incorporated sensors that picked up the electrical messages sent by the operator’s brain: when a person moves the body, he or she first thinks about the motions in his or her brain. By thinking “I want to walk” the brain transmits to the appropriate muscles the necessary signals for the motions through nerves. In an healthy body, each muscle is able to receive those signals from the brain to it and move as strongly and fast as intended. Signals sent to muscles by the brain leak on the skin surface as very weak signals, called Bio-Electric Signals (BES). HAL is able to read BES by only attaching the originally developed detectors on the surface on the wearer‘s skin. By consolidating various information, HAL recognizes what sorts of motions the wearer intends: the movement is performed as a combination of the voluntary control of the wearer read by the BES and an autonomous control in absence of BES by which the suit replicates human motions based on fundamental motion patterns. In such a way, HAL assists the wearer’s motion as he or she intends applying a bigger power that he or she usually exerts. Moreover, the exoskeleton is able to respond as much rapidly to signals received from the brain as a human muscle would do, assisting the wearer’s motion. Once the brain confirm that the body has moved accordingly to the signal sent, assisted by HAL, the movement feeling are fed back to the brain. In such a way, the brain becomes able to learn the way to emit the signals necessary to move gradually [91]. Theoretically, an exoskeleton based on the HAL 5 concept would enable a user to do whatever he or she wanted without moving a muscle, simply by thinking about it. Actually, the HAL 3 exoskeleton is available for therapeutic use, helping people with physical disability; other models are offered for welfare use, like the single and double-leg, for leg movement, and the single-joint, for the knee or the elbow.

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Figure 4.24: Cyberdyne single and double-leg.

Figure 4.25: Cyberdyne single-joint.

4.2.4. ReWalk ReWalk, by Argo Medical Technologies of Israel, consists of a lightweight brace- support suit featuring motors at the joints, rechargeable batteries and a computerized control system carried in a backpack [92]. The exoskeleton would enable paraplegics to not only walk but to stand and even climb the stairs [93]. The challenge here is to design something that imitates a human walking, including universal fit for a broad range of user height, from 160 to 190 cm [94], and weight measurements, as well as a low profile that is both contemporary and user friendly. ReWalk exoskeleton is a light, wearable brace support suit featuring DC motors at the joints, rechargeable batteries, an array of sensors, and a computer-based control system. Users wear a backpack device and braces on their legs, and select the activity they want from a remote control. A sensor on the chest determines the torso’s angle and guides the legs to move forward or backward to maintain balance [95]. The user chooses the desired movement – stand up, take a step, stand still, sit down – on a remote control. Sensors then determine the angle of the user's chest and

114 guide the legs along while allowing the person to maintain his or her balance. The user typically uses crutches while wearing the suit, which is intended to be worn under clothing.

Figure 4.26: ReWalk.

The suit cost is about € 56 000; it has been initially adopted only in hospitals and rehabilitation centers, however the firsts suits home for everyday use start to be introduced. Claire Lomas is the first to take the ReWalk suit home and she used the suit to complete the 2012 London Marathon in 17 days, raising about £ 200 000 for research into spinal damage; later on, she was given the job of lighting the Paralympic cauldron in Trafalgar Square [96]. In January 2013 the updated 2.0 version of ReWalk has been unveiled: the ReWalk 2.0 features include improved sizing, allowing taller individuals to wear it more comfortably, and enhanced controlling software.

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Figure 4.27: Claire Lomas proved the capability of the ReWalk system by using it to walk a complete marathon and then lighting the Paralympic cauldron in Trafalgar Square.

Actually, ARGO offers two ReWalk models: the ReWalk Personal, currently available in Europe and pending FDA review in the US, and the ReWalk Rehabilitation which is now available in Europe, Israel and the United States. Both models are designed to provide a customized user experience with on-board computers and motion sensors that restore self-initiated walking without needing tethers or switches to begin movement. The ReWalk uses patented technology with motorized legs that power knee and hip movement. It controls movement using subtle changes in center of gravity, mimics natural gait and provides functional walking speed. A forward tilt of the upper body is sensed by the system, which triggers the first step. Repeated body shifting generates a sequence of steps, which allows natural and efficient walking.

4.2.5. Tactical Assault Light Operator Suit The Tactical Assault Light Operator Suit (TALOS) is a powered exoskeleton that the U.S. Army intends to design with the help of universities, laboratories, and the technology industry [97]. TALOS was first unveiled by Adm. Bill McRaven, top officer of the Special Ops, during a conference held in May 2013 [98], a first prototype should be available by the first half of 2014 while a more complete version should be ready between 2016 and 2018 [99].

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The armor was inspired to Adm. McRaven by the death of one of his troops in Afghanistan as reported by the admiral to National Public Radio: “One of our folks going through the door was killed by the Taliban on the other side in an attempt to rescue a hostage”. The aim of TALOS would be to provide Special Operations soldiers with a much better and more versatile protection than before: as a matter of fact, it would protect its wearer from bullets, assist in lifting heavy loads and provide the wearer information about their environment using cameras, sensors and advanced displays. The suit is being developed by engineers at MIT, the U.S. Army Research, Development and Engineering Command (RDECOM) and several other companies and academic institutions, with Battelle helping to oversee the integration of these technologies: 56 corporations, 16 government agencies, 13 universities and 10 national laboratories are working all over the program [100].

Figure 4.28: TALOS concept, as in demonstration video from RDECOM.

The suit would be provided with heads-up displays to help military forces synthesize information in their environment: for example, such displays could help military forces identify chemical contamination. If a soldier goes around a corner and sees something yellow oozing from a container, the soldier could consult the display to figure out what the substance is. The display should also provide a night vision-360 degrees visual, giving the

117 wearer the ability to look into the corner of the eyepiece and see the enemy's exact location. Moreover, the suit would be produced with a liquid-ceramic material, developed by Norman Wagner, a professor of chemical engineering at the University of Delaware, in order to give to the wearer a better protection from bullets, and sensors that can detect injuries and apply a wound-sealing foam [101]. TALOS will likely feature a powered exoskeleton for strength and endurance. Two possible candidates are Lockheed Martin’s HULC or Raytheon’s XOS 2. These exoskeletons endow super-strength, allowing soldiers to easily lift weights of a few hundred pounds [102]. A central challenge will be power. The suit would require a battery pack, but even with a good set of batteries, it couldn’t operate for extended periods away from a power source for charging. Moreover, big batteries have been known to explode in electric cars: friendly fire the military would no doubt like to avoid. However, improving battery technology is already getting plenty of dollars and research in the electric car industry. And absent better batteries, the less glamorous solution would be to keep the suit and soldier tethered to a vehicle for heavy lifting.

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5. Conclusions

The study presented in this work has demonstrated how the load carried by soldiers has not changed noticeably in the last two millennia, despite a substantial change of equipment and of military tactics through the years. Several ways to mitigate the effect of the load carried by soldiers have been considered, such as improvement in materials or adopting UGVs and powered exoskeletons. An improvement of the technologies for load carriage (UGV) cannot be considered a valid alternative for the mitigation of the effects of the soldier’s load: UGVs are undoubtedly very useful for the carriage of logistic equipment, however they would be unsuitable to carry the main equipment of a soldier, like weapon, ammunition or armor; indeed such equipment is useful only if the soldiers have it with them: having it on a UGV is like not have it at all. Powered exoskeleton seems to be the best solution; however, considering the state of the art, it is not realistic to have them deployed on the battlefield in the next few years. The improvement in materials is the more suitable solution: lighter and more resistant materials are actually studied, and their application can be employed in the near future.

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Specialized Section

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6. Materials

6.1. Performance Standards Due to the various types of projectile, it is often inaccurate to refer to a particular product as “bulletproof” because this implies that it will protect against any and all threats. Instead, the term bullet resistant is generally preferred. Body armor standards are considered regional, because around the world ammunition varies and as a result the armor testing must reflect the threats found locally. Law enforcement statistics show that many shootings where officers are injured or killed involve the officer's own weapon: as a result, each law enforcement agency or para- military organization will have their own standard for armor performance to ensure that their armor protects them from their own weapons. While many standards exist, a few standards are widely used as models. The US National Institute of Justice ballistic and stab documents are examples of broadly accepted standards. In addition to the NIJ, the UK Home Office Scientific Development Branch (HOSDB – formerly the Police Scientific Development Branch – PSDB) standards are used by a number of other countries and organizations. These “model” standards are usually adapted by other counties by incorporation of the basic test methodologies with modification of the bullets that are required for test. NIJ Standard-0101.06 has specific performance standards for bullet resistant vests used by law enforcement. This rates vests on the following scale against penetration and also blunt trauma protection (deformation) [104]:

Armor Level Protection

This armor would protect against 2.6 g (40 gr) .22 Long Rifle Lead Round Nose (LR LRN) bullets at a velocity of 329 m/s (1080 feet/s Type I ± 30 feet/s) and 6.2 g (95 gr) .380 ACP Full Metal Jacketed Round (.22 LR; .380 ACP) Nose (FMJ RN) bullets at a velocity of 322 m/s (1 055 feet/s ± 30 feet/s). It is no longer part of the standard.

New armor protects against 8 g (124 gr) 9×19mm Parabellum Full Type IIA Metal Jacketed Round Nose (FMJ RN) bullets at a velocity of 373 (9 mm; .40 m/s ± 9.1 m/s (1 225 feet/s ± 30 feet/s); 11.7 g (180 gr) .40 S&W S&W; .45 ACP) Full Metal Jacketed (FMJ) bullets at a velocity of 352 m/s ± 9.1 m/s

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(1 155 feet/s ± 30 feet/s) and 14.9 g (230 gr) .45 ACP Full Metal Jacketed (FMJ) bullets at a velocity of 275 m/s ± 9.1 m/s (900 feet/s ± 30 feet/s). Conditioned armor protects against 8 g (124 gr) 9 mm FMJ RN bullets at a velocity of 355 m/s ± 9.1 m/s (1 165 feet/s ± 30 ft/s); 11.7 g (180 gr) .40 S&W FMJ bullets at a velocity of 325 m/s ± 9.1 m/s (1 065 feet/s ± 30 feet/s) and 14.9 g (230 gr) .45 ACP FMJ bullets at a velocity of 259 m/s ± 9.1 m/s (850 feet/s ± 30 feet/s). It also provides protection against the threats mentioned in [Type I].

New armor protects against 8 g (124 gr) 9 mm FMJ RN bullets at a velocity of 398 m/s ± 9.1 m/s (1 305 feet/s ± 30 feet/s) and 10.2 g (158 gr) .357 Magnum Jacketed Soft Point bullets at a velocity of

Type II 436 m/s ± 9.1 m/s (1 430 feet/s ± 30 feet/s). Conditioned armor (9 mm; .357 protects against 8 g (124 gr) 9 mm FMJ RN bullets at a velocity of Magnum) 379 m/s ±9.1 m/s (1245 feet/s ± 30 feet/s) and 10.2 g (158 gr) .357 Magnum Jacketed Soft Point bullets at a velocity of 408 m/s ± 9.1 m/s (1 340 feet/s ± 30 feet/s). It also provides protection against the threats mentioned in [Types I and IIA].

New armor protects against 8.1 g (125 gr) .357 SIG FMJ Flat Nose (FN) bullets at a velocity of 448 m/s ± 9.1 m/s (1 470 feet/s ± 30 feet/s) and 15.6 g (240 gr) .44 Magnum Semi Jacketed Hollow Point (SJHP) bullets at a velocity of 436 m/s (1 430 feet/s ± 30 Type IIIA feet/s). Conditioned armor protects against 8.1 g (125 gr) .357 SIG (.357 SIG; .44 FMJ FN bullets at a velocity of 430 m/s ± 9.1 m/s (1 410 feet/s ± 30 Magnum) feet/s) and 15.6 g (240 gr) .44 Magnum SJHP bullets at a velocity of 408 m/s ± 9.1 m/s (1 340 feet/s ± 30 feet/s). It also provides protection against most handgun threats, as well as the threats mentioned in [Types I, IIA, and II].

Conditioned armor protects against 9.6 g (148 gr) 7.62×51mm

Type III NATO M80 ball bullets at a velocity of 847 m/s ± 9.1 m/s (2 780 (Rifles) feet/s ± 30 feet/s). It also provides protection against the threats mentioned in [Types I, IIA, II, and IIIA].

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Conditioned armor protects against 10.8 g (166 gr) .30-06

Type IV Springfield M2 armor-piercing (AP) bullets at a velocity of 878 m/s ± (Armor Piercing 9.1 m/s (2 880 feet/s ± 30 feet/s). It also provides at least single hit Rifle) protection against the threats mentioned in [Types I, IIA, II, IIIA, and III].

Table 6.1: Types of armor protection levels.

6.2. Backing Materials One of the critical requirements in soft ballistic testing is measurement of “back side signature”, that is the energy delivered to tissue by a non-penetrating projectile, in a deformable backing material placed behind the targeted vest. Most of military and law enforcement standards have settled on an oil/clay mixture for the backing material, known as Roma Plastilena. Although harder and less deformable than human tissue, Roma represents a “worst case” backing material when plastic deformations in the oil/clay are low (less than 20 mm): as a matter of facts, armors placed over a harder surface are more easily penetrated. The oil/clay mixture of Roma is roughly twice the density of human tissue and therefore does not match its specific gravity; however Roma is a plastic material that will not recover its shape elastically, which is important for accurately measuring potential trauma through back side signature. The selection of test backing is significant because in flexible armor, the body tissue of a wearer plays an integral part in absorbing the high energy impact of ballistic and stab events. However the human torso has a very complex mechanical behavior: away from the rib cage and spine, the soft tissue behavior is soft and compliant. In the tissue over the sternum bone region, the compliance of the torso is significantly lower: this complexity requires very elaborate bio-morphic backing material systems for accurate ballistic and stab armor testing. A number of materials have been used to simulate human tissue in addition to Roma. In all cases, these materials are placed behind the armor during test impacts and are designed to simulate various aspects of human tissue impact behavior. One important factor in test backing for armor is its hardness; as already mentioned, armor is more easily penetrated in testing when backed by harder materials, and therefore harder materials, such as Roma clay, represent more conservative test methods.

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Relative Backer Specific Materials Elastic/plastic Test type hardness Application type gravity vs gelatin

Back face signature Roma Oil/Clay Ballistic and Moderately measurement. Used Plastilina Plastic >2 mixture Stab hard for most standard Clay #1 testing

Good simulant for Animal human tissue, hard to 10% ~1 (90% Softer than protein Visco-elastic Ballistic use, expensive. gelatin water) baseline gel Required for FBI test methods

Good simulant for Animal 20% ~1 (80% skeletal muscle. protein Visco-elastic Ballistic Baseline gelatin water) Provides dynamic view gel of event

Neoprene foam, Slightly Moderate agreement

HOSDB- EVA harder with tissue, easy to Elastic Stab ~1 NIJ Foam foam, than use, low in cost. Used sheet gelatin in stab testing rubber

Long Biomedical testing for Silicone chain Similar to Visco-elastic Biomedical ~1.2 blunt force testing, very gel silicone gelatin good tissue match polymer

Pig or Very complex, requires Sheep Live Real tissue Various Research ~1 ethical review for animal tissue is variable approval testing

Table 6.2: Backer material properties.

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7. Unmanned Ground Vehicles

7.1. Frontline Robotics Teleoperated UGV

Dimensions Specifications

Twin Cylinder, EFI 4-Stroke 680 cc Engine / 40 HP gas powered Length 110 in. (2.8 m) Drive System Automatic PVT

On-Demand True All-Wheel Shaft Width 60 in. (1.5 m) Final Drive Drive with lockable rear differential

Height 75 in. (1.9 m) Max Speed 40 mph (64 km/h)

Fuel System Direct Fuel Injection Type Wheelbase 76 in. (1.9 m) Fuel Tank 9 gal. (34 l) 87 octane (min)

Front – McPherson Strut Suspension Rear – Independent Ground Clearance 10 in. (254 mm) Brake System OEM pedal operated manually driven

Brake System Curb Weight 2 100 lbs. (953 kg) Actuator Controlled remote driven

Parking Brake Actuator Controlled Turning Radius 110 in. (2.8 m) Tires Front/Rear 25x8/25x11-12 Run Flat tires

Power System Environmental

Onan 2.8kW AC Generator generator

4 x Optima D34M Batteries spiral cell, deep- cycle Operating -20°C to 45°C Temperature System Voltage 12 and 24

Individually fused, Power Distribution relay controlled via RS-485

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Loads Vehicle Control

Towing Capacity 1750 lbs. (794 kg) By-wire system for primary and secondary controls

Payload Capacity 1000 lbs. (454 kg) CANbus communication protocol Rear Cargo

Frontline RDC (Robot Data Centre) computer system - rugged MIL-STD-810F computer Payload Capacity 100 lbs. (45 kg) - MIL-C-38999 connectors Front Deck 900MHz wireless communication system Table 7.1: Frontline Robotics Teleoperated UGV [43].

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7.2. Battlefield Extraction-Assist Robot

Dimension Sensors

Height 6 ft. (1.8 m) Infrared

Loads Night Vision

Hydraulic Exertion 3 000 PSI (20.7 MPa) Optical Cameras

Load Lifted 520 lbs. (235.9 kg) Microphone Table 7.2: Battlefield Extraction-Assist Robot [44].

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7.3. Multi-Mission Unmanned Ground Vehicle

Dimensions Specifications

Length 15 ft. (4.6 m)

Width 6 ft. (1.8 m) Load 2 000 lbs. (907.2 kg)

Weight 2 500 kg

Table 7.3: Multi-Mission Unmanned Ground Vehicle [47-49].

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7.4. TerraMax

Specifications

Kit can be installed over a wide range of vehicles

Single operator can supervise up to 5 UGVs in one supply convoy

Navigation can be sustained for over 10 km in GPS-denied environments

Significantly outperforms tele-operated systems with OPTEMPO up to 60 km/h supported in all weather conditions, day or night

Tightly integrated kit enables optional autonomous operation: – Instantly reverts to manned operation when needed – Mobility and payload capacity unaffected by kit installation – Software interprets complex surroundings and coordinates maneuvers with manned vehicles

Additional systems integration via widely adopted open architecture standards

Extensible to route clearance, perimeter security and other operations Table 7.4: TerraMax [50,51].

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7.5. Legged Squad Support System

Dimensions Specifications

Length 6-7 ft. (1.8-2.1 m) Load 400 lbs. (181.4 kg) Height 4.5 ft. (1.4 m)

Total Weight 570 kg Full Loaded Max Speed 16 km/h Sensors

GPS Autonomy 20 mi (32.2 km) Distance Terrain Sensors

Light Sensors Autonomy 24 h Time Sound Sensors

Ranging Sensors Max Power 40 HP Cameras

Table 7.5: Legged Squad Support System [53, 54].

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8. POWERED EXOSKELETON

8.1. XOS 2

Specifications

Load 200 lbs. (90.7 kg)

Actual Weight to Perceived Weight 17 : 1 Ratio

Weight 150 lbs. (68 kg)

Autonomy 24 h Time

Power Source Fuel Table 8.1: XOS 2 [69-73].

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8.2. Human Universal Load Carrier

Specifications [Hulc]

Load 200 lbs. (90.7 kg)

Dimensions Fits warfighters’ height range of 5’4” (1.63 m) to 6’2” (1.88 m)

Weight 53 lbs. (24 kg) Total without batteries

Autonomy 20 km on level terrain at 4 km/h Distance

Speed 3 mph (4.8 km/h) march; up to 10 mph (16.1 km/h) burst

Power Source Lithium polymer batteries Table 8.2: Human Universal Load Carrier [105].

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8.3. Hybrid Assistive Limb

8.3.1. Lower Limb

Dimensions

Size S M L

Height 145 ÷ 165 cm 150 ÷ 170 cm 165 ÷ 185 cm Guideline

Upper leg length Adjustable range 35.0 ÷ 39.5 cm 36.5 ÷ 41.0 cm 39.5 ÷ 44.0 cm [1.5cm × 4 notches]

Upper leg length Adjustable range 33.0 ÷ 40.5 cm 34.5 ÷ 42.0 cm 37.5 ÷ 45.0 cm [1.5cm × 4 notches]

M W Hip width 27.4 ÷ 30.0 cm 33.4 ÷ 36.0 cm

Shoe 22.0, 23.0, 24.0, 25.0, 26.0, 27.0, 28.0 cm

Length Width Height External dimension 469 mm 512 mm 1,102 mm

Double Leg Model Single Leg Model Weight ~ 12 kg ~ 7 kg

Specifics

Hip joint Knee joint Movable range Extension: 20° Extension: 6° Flexion: 120° Flexion: 120°

Body weight limit Lower than 80 kg

Operating Hour 60 ÷ 90 min.

Power Source Custom battery (Lithium Polymer)

Table 8.3: HAL – Lower limb [106].

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8.3.2. Single Joint

Dimensions

Length Width Height External dimension 200 mm 200 mm 944 mm

Weight ~ 1.5 kg

Specifics

Extension: 0° Movable range Flexion: 120°

Operating Hour 120 min.

Power Source Custom battery (Lithium Ion)

Table 8.4: HAL – Single joint [107].

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8.4. ReWalk

Dimensions

Weight ~ 23.3 kg

Specifics

Height range 160 ÷ 190 cm

Body weight limit Up to 100 kg

Operating time 8 h

Power Source Lithium Ion battery

Table 8.5: ReWalk [108, 109].

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8.5. Tactical Assault Light Operator Suit

Features envisioned

Reduced impact of load by intelligent weight distribution throughout the body.

Low power requirement.

Low suit profile to fit under the existing uniform comfortably.

Provide sensor cues to soldiers to reduce injuries.

Integrated components to provide joint support where user needs it most.

Reapply energy to enhance the efficiency of motion and improve overall metabolics.

Remain compliant and flexible stiffening only when needed.

Have the suit weigh less than 400 lb (180 kg) and generate 12 kW of power for 12 hours. Table 8.6: Tactical Assault Light Operator Suit [110].

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[94] ARGO launches ReWalk Rehabilitation 2.0 system, http://www.news- medical.net/news/20130129/ARGO-launches-ReWalk-Rehabilitation-20- system.aspx [95] ReWalk Exoskeleton Helps Paraplegics Walk, http://www.tuvie.com/rewalk- exoskeleton-helps-paraplegics-walk/ [96] C. Wickham, ‘Bionic woman’ Claire Lomas is first woman to take robotic suit home, http://www.independent.co.uk/news/science/bionic-woman-claire-lomas-is- first-woman-to-take-robotic-suit-home-8104838.html [97] US Army RDECOM, Tactical Assault Light Operator Suit (TALOS) Combat Simulation, https://www.youtube.com/watch?v=bPjatYDHJKo [98] Samantha Dean, The U.S. Army Is Building an 'Iron Man' Suit for Soldiers, http://mashable.com/2013/10/13/us-army-iron-man-suit/ [99] Tanya Lewis, U.S. Military's 'Iron Man' Suit Prototype Debuts This Month, http://news.yahoo.com/u-militarys-iron-man-suit-prototype-debuts-month- 152158957.html [100] Brendan McGarry, Admiral: ‘Iron Man’ Prototypes Coming in June, http://defensetech.org/2014/02/11/admiral-iron-man-prototypes-coming-in-june/ [101] Marc Lallanilla, 'Iron Man' Suit Under Development by US Army, http://www.livescience.com/40325-army-iron-man-suit-talos.html [102] Jason Dorrier, US Army to Build Armored TALOS Suit That Merges Man and Machine, http://singularityhub.com/2013/10/21/us-army-to-build-an-armored-talos- suit-that-merges-man-and-machine/ [103] Bulletproof vest, http://en.wikipedia.org/wiki/Bulletproof_vest [104] U.S. Department of Justice, Office of Justice Programs, National Institute of Justice, Ballistic Resistance of Body Armor NIJ Standard-0101.06, https://www.ncjrs.gov/pdffiles1/nij/223054.pdf [105] Lockheed Martin, HULC®, Exoskeletons Enhance Mobility and Increase Endurance, http://www.lockheedmartin.com/content/dam/lockheed/data/mfc/pc/hulc/mfc-hulc- pc-01.pdf [106] CYBERDYNE, HAL® for Lower Limb, http://www.cyberdyne.jp/english/products/LowerLimb_nonmedical.html [107] CYBERDYNE, HAL® for Single Joint, http://www.cyberdyne.jp/english/products/SingleJoint.html [108] ReWalk, http://en.wikipedia.org/wiki/ReWalk 142

[109] ReWalk – Rehabilitation, http://rewalk.com/products/rewalk-rehabilitation/ [110] TALOS (uniform), http://en.wikipedia.org/wiki/TALOS_(uniform)

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Ce.Mi.S.S.1

Il Centro Militare di Studi Strategici (Ce.Mi.S.S.) è l’Organismo che gestisce, nell’ambito e per conto del Ministero della Difesa, la ricerca su temi di carattere strategico.

Costituito nel 1987 con Decreto del Ministro della Difesa, il Ce.Mi.S.S. svolge la propria opera valendosi si esperti civili e militari, italiani ed esteri, in piena libertà di espressione di pensiero.

Quanto contenuto negli studi pubblicati riflette quindi esclusivamente l’opinione del Ricercatore e non quella del Ministero della Difesa.

Aniello RICCIO

Il prof. ANIELLO RICCIO è laureato in Ingegneria Aeronautica presso l’università degli Studi di Napoli “Federico II” ed ha conseguito il titolo di Dottore di Ricerca in Scienze e Tecnologie Aerospaziali presso la Seconda Università degli Studi di Napoli (SUN).

Ha lavorato presso il Centro Italiano Ricerche Aerospaziali (C.I.R.A.) ricoprendo ruoli di responsabilità nel settore delle Strutture e dei Materiali avanzati. Attualmente ricopre il ruolo di Professore Associato in Costruzioni e Strutture Aerospaziali presso la Seconda Università degli studi di Napoli.

Ha un esperienza ventennale nello studio dei materiali avanzati (in particolare di materiali compositi polimerici) e nella loro applicazioni a strutture aerospaziali con particolare riferimento a problematiche di tolleranza al danno. E’ titolare delle cattedre di Strutture Aerospaziali in Materiale composito e di Aeroelasticità applicata presso la SUN. È autore di numerosi articoli su riviste internazionali di prestigio e su memorie di conferenze internazionali. È membro del GoR-SM Group of Responsibles for Structures and Material nell’ambito del Gruppo Europeo GARTEUR (Group for Aeronautical Research and Technology in Europe).

Andrea SELLITTO

Il dott. Andrea Sellitto è laureato con lode in Ingegneria Aerospaziale presso la Seconda Università degli studi di Napoli (SUN) ed ha conseguito il titolo di Dottore di Ricerca in Scienze e Tecnologie Aerospaziali presso la stessa facoltà.

Ha lavorato presso lo stabilimento di Pomigliano d’Arco dell’Alenia Aeronautica (ora Alenia Aermacchi) sul Boeing 787. Attualmente svolge attività di ricerca presso il Dipartimento di Ingegneria Industriale e dell’Informazione presso la Seconda Università degli studi di Napoli nel settore delle Costruzioni Aeronautiche. I suoi principali focus di ricerca sono i meccanismi di danneggiamento sulle strutture in materiale avanzato, principalmente compositi, e metodologie di ottimizzazione multidisciplinare/multiobiettivo.

1 http://www.cemiss.difesa.it