Article Scube—Concept and Implementation of a Self-balancing, Autonomous Mobility Device for Personal Transport Manfred Klöppel 1,2,* , Felix Römer 1,2 , Michael Wittmann 2 , Bijan Hatam 2, Thomas Herrmann 2, Lee Leng Sim 3, Jun Siang Douglas Lim 3, Yunfan Lu 3, Vladimir Medovy 2, Lukas Merkle 2 , Wy Xin Richmond Ten 3, Aybike Ongel 1 , Yan Jack Jeffrey Hong 3, Heong Wah Ng 3 and Markus Lienkamp 2 1 TUMCREATE, 1 CREATE Way, #10-02, CREATE Tower, Singapore 138602, Singapore; [email protected] (F.R.); [email protected] (A.O.) 2 Technical University Munich, Boltzmannstraße 15, 85748 Garching b. München, Germany; [email protected] (M.W.); [email protected] (B.H.); [email protected] (T.H.); [email protected] (V.M.); [email protected] (L.M.); [email protected] (M.L.) 3 Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore; [email protected] (L.L.S.); [email protected] (J.S.D.L.); [email protected] (Y.L.); [email protected] (W.X.R.T.); [email protected] (Y.J.J.H.); [email protected] (H.W.N.) * Correspondence: [email protected]; Tel.: +49-89-289-10332 Received: 19 September 2018; Accepted: 20 November 2018; Published: 5 December 2018 Abstract: Public transportation (PT) systems suffer from disutility compared to private transportation due to the inability to provide passengers with a door-to-door service, referred to as the first/last mile problem. Personal mobility devices (PMDs) are thought to improve PT service quality by closing this first/last mile gap. However, current PMDs are generally driven manually by the rider and require a learning phase for safe vehicle operation. Additionally, most PMDs require a standing riding position and are not easily accessible to elderly people or persons with disabilities. In this paper, the concept of an autonomously operating mobility device is introduced. The visionary concept is designed as an on-demand transportation service which transports people for short to medium distances and increases the accessibility to public transport. The device is envisioned to be operated as a larger fleet and does not belong to an individual person. The vehicle features an electric powertrain and a one-axle self-balancing design with a small footprint. It provides one seat for a passenger and a tilt mechanism that is designed to improve the ride comfort and safety at horizontal curves. An affordable 3D-camera system is used for autonomous localization and navigation. For the evaluation and demonstration of the concept, a functional prototype is implemented. Keywords: autonomous vehicle; first/last mile; public transport; electric personal mobility device; on-demand; prototyping; localisation; 3D-camera navigation 1. Introduction 1.1. Motivation and State of Art Continuing urbanisation and the world’s growing population pose challenges to the provision of public services, economic opportunity, and maintenance of liveable spaces, particularly for megacities. In 2016, 25 megacities with a population of over 7 million people were housing 453 million people [1]. According to the United Nations [1], the proportion of the world’s population living in urban areas is expected to increase to 66% by 2050, while the number of megacities is projected to reach 42 by World Electric Vehicle Journal 2018, 9, 48; doi:10.3390/wevj9040048 www.mdpi.com/journal/wevj World Electric Vehicle Journal 2018, 9, 48 2 of 15 World Electric Vehicle Journal 2018, 9, x FOR PEER REVIEW 2 of 15 2030.reach One 42 by of 2030. the main One challenges of the main of challenges increasing urbanisationof increasing isurbanisation traffic congestion is traffic due congestion to the increased due to demandthe increased for transportation. demand for transportation. Policies promoting Policies a modal prom shiftoting from a modal private shift cars from to publicprivate transportation cars to public (PT)transportation have been (PT) a key have area been of interest a key area not onlyof interest to reduce not only externalities to reduce that externalities are caused that by theare caused use of privateby the use cars, of however private cars, also however to reduce also the to land reduce that isthe devoted land that to is private devoted cars. to private However, cars. PT However, systems oftenPT systems suffer fromoften the suffer disutility from ofthe not disutility being able of not to deliverbeing able users to all deliver the way users from all their the way point from of origin their topoint their of destination. origin to their According destination. to Polzin According [2], people to Polzin do not [2], want people to transfer do not modes want to unless transfer necessary: modes theunless out-of-vehicle necessary: timethe out-of-vehicle spent transferring time isspent perceived transferring two or is more perceived times moretwo or unfavourably more times thanmore in-vehicleunfavourably travel than time. in-vehicle Therefore, travel this first/lasttime. Therefor mile probleme, this first/last deters transit mile useproblem even thoughdeters transit a high use PT serviceeven though quality a ishigh provided PT service for the quality majority is pr ofovided the ride for distance.the majority of the ride distance. PersonalPersonal mobilitymobility devicesdevices (PMDs)(PMDs) whichwhich havehave recentlyrecently enteredentered thethe roadroad transporttransport systemsystem cancan provideprovide aa solution solution to to first/last first/last milemile problemsproblems whenwhen coupledcoupled withwith PTPT services.services. However,However, theirtheirusage usage potentialpotential hashas beenbeen limited by their their safety safety and and ease ease of of use. use. Most Most of ofthem them require require learning learning effort effort of the of therider rider and and require require a standing a standing riding riding position position which which makes makes riding riding difficult difficult for elderly for elderly people people or people or peoplewith disabilities. with disabilities. And even And eventhough though most most PMDs PMDs can canbe befolded, folded, carrying carrying the the device device on on board ofof aa crowdedcrowded busbus oror traintrain cancan bebe difficult.difficult. PMDsPMDs withwith seatsseats areare alsoalso available,available, howeverhowever riderrider comfortcomfort isis affectedaffected byby roadroad inclinations.inclinations. PMDsPMDs withwith aa standingstanding ridingriding positionposition allowallow thethe riderrider toto leanlean intointo thethe curvecurve to to compensate compensate for for the the occurring occurring centrifugal centrifugal forces, forces, while while PMDs PMDs with with a seat a need seat toneed reduce to reduce speed duringspeed during turns to turns avoid to discomfort avoid discomfort and the and toppling the topplin of theg vehicle. of the vehicle. Existing Existing tilt mechanisms tilt mechanisms to reduce to occurringreduce occurring forces from forces vehicle from movement vehicle movement only react afteronly an react acceleration after an isacceleration sensed bythe is sensed system whichby the resultssystem in which a latency results between in a latency the occurrence between of the the occu forcesrrence and of the the counter-measures forces and the counter-measures of the system [3–6 of]. Currently,the system most [3–6] PMDs. Currently, are controlled most manuallyPMDs are by thecontrolled rider, however manually the introductionby the rider, of however autonomous the capabilitiesintroduction could of autonomous increase rider capabilities comfort and coul drivingd increase safety. rider comfort and driving safety. PMDsPMDs are are available available in differentin different form form factors factor ands technical and technical implementations. implementations. The Segway The PersonalSegway TransporterPersonal Transporter is an example is an of example a PMD onof a which PMD the on riderwhich is the standing rider is while standing riding. while Figure riding.1a shows Figure the 1a Segwayshows the i2 whichSegway was i2 which introduced was introduced in 2006 [7]. in The 2006 Segway [7]. The weighs Segway 47.3 weighs kg and 47.3 allows kg and people allows to people travel attoa travel speed at of a upspeed to 20 of km/hup to 20 and km/h with and a range with ofa range up to of 39 up km to [ 839]. km Figure [8].1 Figureb pictures 1b pictures the Scewo the Bro,Scewo a self-balancing,Bro, a self-balancing, electric electric wheelchair wheelchair which provides which prov a seatides for a oneseat person for one and person is able and to climbis able stairs to climb [9]. Thestairs vehicle [9]. The weighs vehicle 120 weighs kg and 120 travels kg and at 10 travels km/h at with 10 km/h a range with of a 25 range km. of 25 km. TheThe AirwheelAirwheel X8X8 isis shownshown inin FigureFigure1 c.1c. It It is is an an electric electric unicycle unicycle where where the the rider rider stands stands in in an an uprightupright positionposition andand controlscontrols thethe speedspeed andand directiondirection byby thethe leaningleaning ofof thethe body.body. FigureFigure1 d1d shows shows thethe ZoomZoom Stryder Stryder EX EX electric electric scooter scooter which which is is foldable. foldable. BothBoth thethe AirwheelAirwheel X8X8 unicycleunicycle andand thethe ZoomZoom StryderStryder EX EX electric electric scooter scooter are are targeted targeted for for daily daily commuters commuters who who use use the devicesthe devices to cover to cover the last-mile the last- betweenmile between their hometheir andhome the and station the andstation take and the devicestake the with devices them with onto them trains onto and trains buses. and Therefore, buses. theyTherefore, are lightweight they are (11.1lightweight kg; 10.7 (11.1 kg) while kg; 10.7 the Airwheelkg) while X8the offers Airwheel a travel X8 speed offers of a 18travel km/h speed with of a range18 km/h of 23with km a [ 10range], and of the23 km Zoom [10], Stryder and the EX Zoom offering Stryder a travel EX speed offering of 30a travel km/h speed and an of electric 30 km/h range and ofan approximately electric range of 30 approximately km [11].