The Fully Automatic Rubber Tapping Machine Y.A.I

ENGINEER - Vol. LII, No. 02, pp. [27-33], 2019 © The Institution of Engineers, Sri Lanka DOI: http://doi.org/10.4038/engineer.v52i2.7351

ENGINEER - Vol. LII, No. 02, pp. [page range], 2019 © The“Appuhamy Institution of Engineers,” Sri -Lanka The Fully Automatic Rubber Tapping Machine Y.A.I. Yatawara, W.H.C. Brito, M.S.S. Perera and D.N. Balasuriya

Abstract: Being a major export good from the colonial times, rubber still can greatly contribute to the national economy. However, lack of labour for rubber tapping has been a major factor contributing to the downfall of the Sri Lankan rubber industry. As a solution to the shortage of labour for rubber tapping we present the design of a fully automated rubber tapping machine which is capable of moving from tree to tree in a rubber plantation and tapping each tree automatically. Capability to automatically detect the tapping path, nodules, tree condition and many other important parameters makes the proposed rubber tapper much more superior over all existing rubber tapping machines and techniques.

Keywords: Rubber tapping, Fully automatic

1. Introduction rubber is preferred wherever possible. Labour intensiveness in the tapping process for the Rubber is a substance which possess special natural rubber and also the introduction of synthetic rubber has paved the way to the properties such as elasticity, high friction, downfall of the natural rubber industry in Sri softness, durability and very high electrical Lanka. Furthermore, the export oriented resistivity, hence is employed in an array of industries like garments have further absorbed products used in our day to day life. From the labour force; hence rubber industry has surgical gloves to automobile parts and from become a dying industry in Sri Lanka. toys to electrical insulators, rubber is a key element in the production of nearly 50,000 Even though the synthetic rubber is a good products we use on a daily basis. To cater for substitution for many of the natural rubber this multi-fold requirement, today’s world is based products, there are some products which producing approximately 26 million metric tons still appreciate the unique properties of natural of rubber annually, out of which only 12 million rubber. This requirement has paved way to a considerable market segment left for the is natural rubber [1]. To cater for the excess developing nations with agriculture based demand, 14 million tons of various synthetic economics to compete in. On the other hand, rubber forms are also produced. Introduced to with a low level technological background, Sri Sri Lanka by the Colonial English rulers, Lanka is unable to compete with the synthetic natural rubber has been a major export good of rubber producers, but would be able to Sri Lanka even after the independence. Later, compete in the natural rubber market under under the import substitution economic policies sufficient technological involvement. during 1972-1977, rubber became the key ingredient in many local industries such as Eng. Y.A.I. Yatawara, AMIE(SL), B.TechEng.Hons(OUSL) Engineer, Nokia Corporation Lanka (Pvt)Ltd, Comombo 01. Kelani Tyres and Richard Peris Rubber products. Email:[email protected] Even under the open economic policies during ORCID ID: https://orcid.org/0000-0002-8112-8801

1980’s, rubber retained its position as a major Eng. W.H.C. Brito, AMIE(SL), B.TechEng. Hons(OUSL) source of export income to the Island [2]. R&D Engineer, Novena Tech (Pvt)Ltd, Dutugemunu St, Kohuwala. Email:[email protected] ORCID ID: https://orcid.org/0000-0002-5017-424X At the same time, many of the Asian countries such as India and Malaysia have steered Eng. M.S.S. Perera, AMIE(SL), B.TechEng.Hons(OUSL) themselves to be the world’s largest natural Lecturer, Department of Electrical and Computer Engineering, The Open University of Sri Lanka, Nawala, rubber producers. Meanwhile, the technically Nugegoda. Email:[email protected] advanced western world has focused their ORCID ID: https://orcid.org/0000-0003-3747-3840 attention on the production of synthetic rubber Eng. D.N. Balasuriya,CEng, MIE(SL),BSc which has overtaken the role of natural rubber Eng.Hons(Moratuwa), MSc (Manitoba), over the last few decades. Due to its high - tech Senior Lecturer, Department of Electrical and Computer driven low cost mass production capability Engineering, The Open University of Sri Lanka, Nawala, compared to the highly labour intensive small Nugegoda. Email:[email protected] scale production of natural rubber, synthetic ORCID ID: https://orcid.org/0000-0002-0073-7091

This article is published under the Creative Commons CC-BY-ND License (http://creativecommons.org/licenses/by-nd/4.0/). This license permits use, distribution and reproduction, commercial and non-commercial, provided that the original work is properly cited and is not changed in anyway. 1

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Thus, if a solution can be provided to the a cost disadvantage. Other considerable It also detects the distance to the rubber tree removal of bark. This cutter can be used to meet shortage of labour and if the rubber industry contribution in this area is from the semi- and selects the depth of the cut. Moreover, the the industrial requirements and specifications can be rehabilitated, there would be a automated rubber tapping machine developed head carriage is a mechatronics arrangement in rubber tapping to maintain a 10 degree slope considerable market and income for Sri Lankan at the Velammal College of Engineering which moves the tapping head along the across the depth of the cut with the use of a natural rubber. Technology, India [4].The key concept behind tapping trajectory. At the same time, the main tapered rotary cutter body. The cutter head can this machine is the introduction of the carriage is an arrangement to carry the rubber also be inclined accordingly using a separate As a solution we present the design of a fully rotational cutter to produce a low torque cut. A tapping machine from tree to tree during the gear wheel fixed to the fixture. This allows the automated rubber tapping machine which can worker needs to carry the machine from tree to tapping process. Note that all these units are tool to be always kept in an approximate automate the process of rubber tapping tree to perform a cut but takes a lesser time to controlled by a single controller unit. perpendicular orientation to the tree surface. reducing the labour requirement to a minimum. tap than in a manual tapping. Even then, this The rest of the paper is organized as follows. cutter too needs a considerable human 3.1 Intelligent Tapper Head Section 2 discusses the currently available semi- involvement as it needs to be taken from tree to The tapping process of a rubber tree is carried automated rubber tapping systems around the tree, very similar to the conventional manual out along an inclined circular path along the Slope towards the world. In Section 3 we present the proposed rubber tapping process. rubber tree surface. Every day, a slim line of tree is 10˚ fully automated rubber tapping machine bark is removed along the cut together with the design. In Section 4, we further elaborate on the Therefore, in this research, we propose a fully clogged latex, known as ottapalu, resulting from functionality of the proposed rubber tapping automated latex tapping machine which neither the previous cut. The intelligent tapping head machine followed by the prototype needs to be carried from tree to tree manually mainly focuses on the identification of the Figure 3 - Rotary cutter head implementation details and the testing results. nor needs to be programmed with the tapping tapping path of each and every rubber tree. Finally, Section 5 concludes the paper path on a tree by tree basis. This action is vital in the process of designing a Moreover, it is highly recommended for the highlighting several future research and fully automated rubber tapper as the automatic tapper to remove the bark of the tree development avenues. 3. Design Methodology path detection enables the tapper travelling completely to capture the total number of latex

from tree to tree to identify the tapping vessels, while not harming the inner tree which 2. Automatic Rubber Tapping Systems The proposed fully automated rubber tapping trajectory without pre-programming. is known as the Cambium, as shown in Figure 4. machine consists of several important sub units Cambium During a fully manual rubber tapping process as depicted in Figure 1. The path identification mechanism is to be with the conventional rubber tapping knife, a H bridge based on image processing. Several tapper makes an incision in the bark of the photographs around the tree are captured Camera circuits and rubber tree which causes the slow flow of the under constant lighting conditions, and the X-Y motors milky fluid “latex”. This procedure is known as photographs are overlapped first to form a tapping. Latex is allowed to be collected in a single image. Then the resulting image is container which is then collected and taken for H bridge Ultrasonic converted to black and white via binary processing. An individual tapper needs to visit Main circuits and sensor thresholding [5] and then inverted. The each and every tree and it takes approximately Control Z & cutter resultant black spaces along the tapping path (a) (b) (c) five minutes to clean and tap a single tree and a Unit aligning are interpolated for a continuous trajectory and Figure 4 - The tapping cut (a) Under cut further visit to each and every tree is also Moisture motors the resulting trajectory coordinates are recorded (b) Optimal cut (c) Over cut needed to collect the latex. With this labour sensor as a two dimensional data array as shown in intensive nature, an individual tapper may H bridge Figure 2. The recoded trajectory is utilized for To cater for this requirement, in addition to the manage to tap only a few acres of rubber and main Rainsensor moving the cutter head during the tapping blades, the cutting head consists of a plantation per day. carriage stage. protruding 1.5 mm diameter semi global motor dotwhich prevents the cutter tool moving too To overcome this issue, several semi-automated Tree far into the tree (Figure 5). rubber tapping machines have been proposed. The invention of the semi-automated rubber IR grippermoto r tapper at Palai College of Engineering sensor Technology, India [3], which is based on a array Motor Protruding linear cutter and a manual fixing mechanism, is driver and dot one such attempt. A tapping machine is to be GSM cutter motor fixed to each and every tree which carries out communi Figure 2 - Tapping tragectory identification the movement of the cutting blade across a pre- cation programmed path. One of the major drawbacks Unit 3.2 Rotary Cutter and the Cutter Head of this machine is the high torque generated Figure 5 - Protruding dot arrangement Moving Mechanism with the linear cutting which is not possible to One of the most innovative features of this be applied with a small motor. Moreover, this Another major issue that an automated tapping Figure 1 - System block diagram system is the inclusion of a rotary cutter in view cutter is only developed at an experimental head faces is the unevenness in the depth to the The intelligent tapper head is one of the main of a reduced torque. For efficient cutting, a slit level and with the clogging properties of latex, tree surface from the two dimensional plane components in this system which includes all with a slope to the horizontal on half a the practical deployment of this cutter is where the machine chassis is located. Thus, to the sensors and the camera and is capable of circumference of the particular rubber tree doubtful. On the other hand, the need of a cater for this issue, an inward and outward capturing the images of the rubber tapping needs to be cut. Here, a fixed cutter consisting separate machine for each and every tree poses moving mechanism for the cutter head is path and determining the trajectory of the cut. of four blades, was designed to allow the easy

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proposed. This mechanism is aided by a depth we denote as X-Y movement is achieved by so that the tapper can travel along the steel detection mechanism implemented using an appropriately varying the horizontal and guide wire to the next tree. infrared (IR) sensor and an ultrasonic sensor vertical coordinates of the tapper head fixed to a panel at the head [6].With the according to recorded two dimensional data The movement from tree to tree is achieved detected depth to the tree, the cutter will move array. Two motors fixed to two screwed shafts using an H-bridge controlled motor [7] fixed in and out with respect to the tree (we denote (controlled via H-bridge circuits [7]) produce with a rubber belt; pushing against the steel this as Z movement). Even in the presence of the necessary horizontal and vertical motions guide wire forcing the carriage to move with Automatic Rubber nodules on the tree surface the above (Figure 7). Furthermore, in order to match the respect to the wire due to friction. Tapping Machine mechanism performs a precision cut without speed requirements, a gearwheel arrangement the need of any further hardware. is employed in this design. Moreover, an automatic tree presence detection

mechanism is implemented using an ultrasonic Figure 8 - Proposed fully automatic main Meanwhile, it is of high importance to maintain Note that the design of a main carriage which sensor fixed to the carriage facing the tree side carriage the cutter approximately perpendicular to the performs an X-Y movement in a plane rather of the line. Automatic tree presence detection tree surface throughout the cutting path. Note than rotating around the tree is solely for the and clamping control is to be controlled via the that the tapping head moves in an X-Y plane purpose of facilitating an easy tree to tree same control unit as employed for the tapper 4. Operation and the Prototype while the cutter is capable of moving in the Z movement along the guide wires. control. Furthermore, the GSM communication Implementation direction. Thus, we incorporate another degree unit is used to notify a predefined mobile user of freedom for the cutter such that the cutter when the carriage reaches the end of the line, The three sub systems are to be integrated 3.4 Main Carriage angle can be varied with the help of another thus has finished the tapping process. together to perform a complete system which is The rubber tapping machine requires to be capable of moving from rubber tree to another, motor and a gear system, within a range moving from tree to tree (Figure 8). Thus, a [ ]. identify the tapping trajectory, remove clogged main carriage as in Figure 9 is employed to latex and clean the tree, perform a cut and then −90° 𝑡𝑡𝑡𝑡 + 90° hold the rubber tapper, and the carriage moves move to the next tree. D along a pair of guide wires laid along the line of θ =+90o θ =-90o trees. At each tree, two steel arms connected to the rubber tree hold the steel cable. The carriage moves along these wires using a pulley mechanism as shown in Figure 9. Extra grooves Motor Tree fixing θ on the pulleys, high tension in the steel wires arrangement o θ =0 and the shorter inter-tree distance below 5 meters ensure that the carriage does not get Figure 6 - Proposed cutter angle aligning derailed while moving from tree to tree. arrangement

Cutter’s angle to the Z direction given by is Screw for calculated and varied as, , where Main 𝜃𝜃 horizontal 180° ×𝛿𝛿𝛿𝛿 carriage and are the horizontal displacement of the (X) 𝜃𝜃 = 𝐷𝐷 𝛿𝛿𝛿𝛿 Gripper fixture cutter head from the center of the X direction movements trajectory𝐷𝐷 and the total length of the X direction arm trajectory, respectively (Figure 6). This Steel ball Rotarycutter Steel technique enables the cutter to be maintained screw for head wire approximately perpendicular to the tree surface Depth(Z) throughout the horizontal movement of the movements cutter head. Camera Design of the automated rubber tapper also module Pulley involves the addition of a rotating tangler arm Tapping Motor mechanism in front of the cutter to collect the Steel ball head clogged latex from a previous tapping. screw for carriage Furthermore, tree’s surface moisture level vertical(Y) sensor and a rain sensor are also included movements Gripper which are vital to avoid excess water in the arm Figure 9 - Main carriage movement mechanism clogged latex. Figure 7 - Proposed carriage hardware

arrangement 3.3 Tapping Head Carriage Tapping head is fixed in a movable carriage At a tree, two expandable gripper arms are which moves in a plane and in an inclined non- operated to clamp the tapper to the tree. After linear path following the trajectory coordinates the tapping process of the same tree is captured at the start. This special motion which completed, these arms de-clamp from the tree

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imite suiht hus, the automate ruer Start tai machie is esie to oerate for seera hours soe o the atter oer he roose automate ruer tai Furthermore, sesor arras a sstem i e of immese aue to the ri F utrasoic rae fiers are emoe i aa ruer atatio sector as it aois No No Tree present ? End of tree line ? the machie for etectios ther e most of the maor roems associate ith the comoet i this machie is the camera, for tai rocess i a efficiet a rotote imemetatio emostrate its Yes Yes hich a hih resoutio ‘Mind vision mv ub500c’camera is seecte toether ith iaiit for a mass scae rouctio at a fair Clamp to the tree automatic ihti cotro cost

Stop he cotroi uit of the tai machie is oeer, there are seera eaesses i the resosie for ma fuctios icui imae roose sstem hich shou e aresse i future imroemets e such eaess is the Rain and tree surface moisture No rocessi for traector ietificatio, below threshold ? cotroi the horiota, ertica a eth fact that the mai carriae traes ao a air moemets rii the aroriate motors, of uie ires roer mechaism to aoi a aso ietificatio of the resece of a the effect of i to this moemet is esire Yes ruer tree ith a ifrare roimit etector t the same time, the moemets ee to herefore, a aserri miicomuter oar e soe o i the resece of oues, Capture two photos and is use i this cotroi hich is aother issue to e aresse i future process for the esis trajectory rotote as imemete hai a aforemetioe uits, ut ecui the mai carriage’s moving mechanism, which eihe icui the atter Fiure uthors ish to acoee the suort etee aeea erera i reari X-Y movements the rais

No Start of trajectory ? teratioa uer tu rou, ”Current evelopments in the Rubber Industry”, Yes he etra a of ri aa, ”Sri Lanka Socio Depth calculation & X-Y-Z coomic ata”, o ,

movements oseh, ”Automatic uer ree ai achine”, ia atet o No End of trajectory ? aarmaa, , eathesh, , ichars, Yes a aesh aa, , ”Semi Automate uer ai achine”, ia atet o De-clamp & operate the main carriage moving motor ei, a aur, ”Survey over mae hreshoi echiues a uatitatie erformace valuation”, oura o ectroic mai,o,ssue , ,

riasthaa, , erma, a ih, , ”Distance easuremet of a ect or stace trasou esors usi he overall operation can be depicted as in employed or providing the necessary torue P89C51RD2”, teratioa oura of omuter igure 10 In this design, the tapper head is or the rotational cutter he system is operated heor a ieeri,o, o,, operated by a 12 , A DC motor while the with a 2 , 00 Ahr rechargeable battery pack same ru ith the imemete rotote main carriage, head carriage and the tree to tree emostrate a aerae tai time of moving mechanism are operated using three ven though in young rubber plantations secos for oe tree hich is er much hu, , im, a assia, ”Hrie rie ircuit for te otor ontrol”, US patent 2 , A stepper motors All motors are driven where the ground level receives suicient suerior to the time set most of the o using Hbridges and L298DMD20 motor sunlight to energie a solar cell generator, in eisti tai mechaisms controller boards Another 12 DC motor is mature plantations ground level gets very

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No Start of trajectory ? teratioa uer tu rou, ”Current evelopments in the Rubber Industry”, Yes he etra a of ri aa, ”Sri Lanka Socio Depth calculation & X-Y-Z coomic ata”, o , movements oseh, ”Automatic uer ree ai achine”, ia atet o No End of trajectory ? aarmaa, , eathesh, , ichars, Yes a aesh aa, , ”Semi Automate uer ai achine”, ia atet o De-clamp & operate the main carriage moving motor ei, a aur, ”Survey over mae hreshoi echiues a uatitatie erformace valuation”, oura o ectroic mai,o,ssue , ,

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