CAD PROJECT AND PROTOTYPE FOR AN ANTHROPOMORPHIC GRIPPER FOR ROBOTS - SIMULATION AND TESTING

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1 Proceedings of the Annul Symposium of the Institute of Solid Mechnics nd Session of the Commission of Acoustics, SISOM 2015 Buchrest My CAD PROJECT AND PROTOTYPE FOR AN ANTHROPOMORPHIC GRIPPER FOR ROBOTS - SIMULATION AND TESTING Ionel STARETU, Ctlin MOLDOVAN Trnsilvni University of Brsov, Romni, emil: istretu@yhoo.com This pper presents n nthropomorphic gripper intended to equip industril roots used to chieve low nd medium complexity ssemlies. The gripper hs five fingers nd five degrees of moility; it hs reltively simple structure, ut high functionlity. Bsed on the CAD project of the gripper, we otined prototype through rpid prototyping. An ctutor controlled y microcontroller ctivtes ech finger. The gripper control is possile cpturing humn hnd gestures nd trnsmitting dt first in virtul scene to certify the gripper correctness then to the rel gripper. The prototype ws tested for gripping ojects of different shpes nd sizes. Keywords: nthropomorphic gripper, CAD project, CAD simultion, prototype. 1. INTRODUCTION Anthropomorphic grippers re grippers inspired y humn hnd model, with vrious constructive nd functionl fetures. Compred to other clsses of grippers, like grippers with jws [1,2], or tentculr grippers [2], nthropomorphic grippers hve ovious dvntges ecuse they re more similr to humn hnd, oth constructively nd functionlly, considering the humn hnd the most dvnced gripper [1]. Currently, there re severl versions of nthropomorphic grippers, some of which re in the design stge, others in the prototype stge nd some re commercil products [3,4,5,6,7,8]. These grippers differ through more constructive nd functionl fetures, including the min ones: the numer of fingers tht cn e: 2,3,4,5 or even 6; the numer of phlnges on the finger: 2 or 3; the mechnisms type - significnt constructive elements for fingers: rticulted rs or rollers or wires; degree of moility, y which there cn e monomoile versions to multimoile versions, with high degree of moility, equl to the fingers numer, or even very high, equl to the phlnges numer, respectively with the joints numer, degree of moility close or equl to the humn hnd (M = 36); motors type used: electricl or pneumtic; with or without sensors nd sensors type used: contct, sliding, proximity; type of control system used: through progrm instructions, y glove-devices, Dt Glove type, through virtul relity, through smrtphone, voice, etc. Compring significnt numer of nthropomorphic grippers versions for roots, we cn identify the following mjor drwcks: excessive complexity compred with low functionlity; low technologicity; high or very high cost nd especilly price most of the times without high performnce nd reliility, etc. In this context, this pper proposes some new pproches, to reduce t lest in prt the disdvntges outlined ove, pproches focused on: - chievement of technicl project, CAD model nd functionl simultion of n nthropomorphic gripper with five fingers, with high degree of similrity to the humn hnd; - controlling the gripper through topicl solution, nmely y cpturing configurtions-gestures of humn hnd nd dt trnsmission to simulte gripping in virtul scene nd then to the rel gripper; - chieving prototype using modern nd less costly method, nmely the method of virtul prototyping. ACTA ELECTROTECHNICA, Volume 57, Numer 1-2, 2016, Specil Issue, ISSN

2 CAD Project nd Prototype for n Anthropomorphic Gripper for Roots - Simultion nd Testing CAD MODEL AND FUNCTIONAL SIMULATION OF AN ANTHROPOMORPHIC GRIPPER WITH FIVE FINGERS 2.1. Structurl nd functionl peculirities of the gripper To equip the root from rootic worksttion, looking like other similr ones, for smll nd medium ssemlies [9], we decided to use n nthropomorphic gripper with five fingers, with n incresed numer of joints ove the minimum, to find resemlnce nd functionlity s close s possile to the humn hnd. We strted from known model [10], which ws dpted to the purpose intended. Ech finger consists of three phlnges: f 1,f 2,f 3, etween which there re monomoile rottionl couplings, driven y wires (Figure 1). For driving we use electric motors, one for ech finger, so tht the gripper hs the moility degree M = 5. To close the finger, the motor rottes in one direction, nd closing is otined y pulling the thred f i, nd the opening the return of the finger to the strting position, corresponds to the motor rottion in the opposite direction, nd it is otined y pulling the outer wire f e (Figure 1). The structurl digrm of the gripper ws otined sed on 17 monomoile rottionl couplings: 10 interphlngel joints, 3 couplings of the first three phlnges of the thum, nd the first two fingers nd the plm, 4 connection couplings etween two prts tht replce metcrpl ones for the lst two fingers, connection couplings with the plm nd the first phlnges of these fingers. We highlight the two rottion couplings with the inclined xes reported to the longitudinl xis of the gripper, which provides to certin degree resemlnce to the sitution of humn hnd metcrpl ones existence [2] CAD model of the gripper The CAD model of the gripper ws otined using CATIA softwre [11] nd it is shown in Figure 1. Figure 1. Scheme of finger () nd CAD model of the nthropomorphic gripper designed () The sme softwre cn e used for the functionl simultion of the gripper to check the correct closure without prt to grip or with gripping prts of vrious shpes nd sizes (Figure 2). ACTA ELECTROTECHNICA, Volume 57, Numer 1-2, 2016, Specil Issue, ISSN

3 162 Ionel STARETU, Ctlin MOLDOVAN Figure 2. CAD simultion of gripping using the designed nthropomorphic gripper Bsed on the CAD model of the gripper, we otin the technicl documenttion necessry to chieve the pproprite prototype. 3. GRIPPER CONTROL The gripper control is possile using method of cpturing the humn hnd configurtions. On this purpose, we use Lep Motion device (Figure 3) [12]. In Figure 3 there is the interction cue, re where humn hnd finger movements cn e cptured. Figure 3. Functionl peculirities of the Motion Lep device It hs the ility to cpture the configurtion of the fingers, Figure 4, similr to the configurtion, which would grip specific oject. Dt otined, Figure 4, nd vlidted y gripping virtul oject similr to the rel one, y similr virtul gripper, Figure 4c, re trnsmitted finlly to the rel gripper [12]. ACTA ELECTROTECHNICA, Volume 57, Numer 1-2, 2016, Specil Issue, ISSN

4 CAD Project nd Prototype for n Anthropomorphic Gripper for Roots - Simultion nd Testing 163 c Figure 4. Stges of cpturing configurtions of humn hnd fingers with Motion Lep device This method cn e improved oth y incresing functionl performnces of the Motion Lep device, incresing its ccurcy nd y optimizing gripping simultion in virtul environment, including y incresing the numer of constructive detils of the virtul gripper, to hve construction nd opertion identicl to those of the rel gripper. 4. GRIPPER PROTOTYPE AND TESTING ITS PERFORMANCE Bsed on the technicl project prototype of the nthropomorphic gripper ws mde. The prts were otined y rpid prototyping using 3D printer. In Figure 5 we cn see the components of finger (Figure 5) nd prt of the plm where we cn notice the re of the inclined joints (Figure 5) [12]. Figure 5. Components of the gripper prototype mde y rpid prototyping Ech finger is operted vi wire, with one ctutor type Tower Pro MG 995 (Figure 6) controlled y microcontroller ATMeg32u4 type (Figure 6). The ctutor hs the following technicl chrcteristics: working voltge: 6V, torque: 180N / cm, dimensions: 44x23x25, weight: 35 grms, nd the controller hs the following min fetures: working voltge: 5V digitl input nd output pins: 20, PWM chnnels: 7, input nlog chnnels: 12, flsh memory: 32 K, processor frequency: 16 Hz [12] Figure 6. The ctutor () nd the microcontroller () used ACTA ELECTROTECHNICA, Volume 57, Numer 1-2, 2016, Specil Issue, ISSN

5 164 Ionel STARETU, Ctlin MOLDOVAN The opertion of ech finger is possile through single tendon, which is pulled y the motor nd induces rottion to rollers in interphlngel rottion joints, nd to the phlnges s well. On the rottion of the ctutor in one direction, the finger closes, nd on moving in the opposite direction, the finger returns to the initil position (position rectiliner-open finger). In Figure 7 it is shown the prototype chieved, nd in c d Figure 7. Simultion of nthropomorphic gripper prototype functioning: no gripped oject (, ) nd with gripped oject (c- tennis ll, d- n xis) Figure 7, functionl simultion where it is oserved good hndling of fingers. Functionl testing ws performed for severl ojects prts out of which we hve two exmples, nmely: gripping sphericl oject ( tennis ll) in Figure 7c nd gripping n xis (Figure 7d) [12]. From these exmples results the high functionlity of the gripper compred to other types of grippers, such s jw-grippers [2]. 5. FUTURE DEVELOPMENTS To continue presenting our chievements, we seek to otin functionl susystem where the gripper otined is controlled y cpturing humn hnd gestures with Motion Lep device, vi gripping simultion in virtul scene, nd the root cn e controlled y cpturing humn rm movements with Kinect device. The min softwre interfces required re Roocommnder, lredy mde, in the cse of the gripper nd ABBcommnder, in progress, in the cse of the ABB type root. ACTA ELECTROTECHNICA, Volume 57, Numer 1-2, 2016, Specil Issue, ISSN

6 CAD Project nd Prototype for n Anthropomorphic Gripper for Roots - Simultion nd Testing CONCLUSIONS On the sis of this work the following conclusions cn e drwn: - to eliminte the disdvntges of the jw-grippers, of which the most importnt is reduced gripping possiility, sometimes limited to single workpiece size, the use of nthropomorphic grippers with three or more fingers, with reltively simple structures ut high functionlity, is recommended; - to equip the root or the roots, we cn use nthropomorphic grippers with five fingers, s shown in the pper, which cn e otined t low cost, using modern techniques such s rpid prototyping; - to optimize the root nd gripper opertion control, dvnced methods cn e used, such s cpturing fingers movements to control the gripper, nd humn rm movements for the root control. ACKNOWLEDGEMENT We thnk the Germn Compny Cloos nd its representtive in Romni, Rocon, which gretly supported the reserch fter which we otined more vlule results, some of which re presented in this pper. REFERENCES 1. STAREȚU, I., Gripping systems(in Romnin), Lux Liris Pulishing House, Brsov, Romni, STARETU, I., Gripping systems, Derc Pulishing House, Tewksury, Msschusetts, USA, KAWASAKI, H., KOMATSU, T., UCHIYAMA, K., Dexterous nthropomorphic root hnd with distriuted tctile sensor: Gifu hnd II, IEEE/ASME Trnsctions on Mechtronics, 7(3), , Aville online t: /products/, Aville online t: uplods/eionic-product-brochure-finl.pdf. 6. BIRGLEN, L., GOSSELIN, C., Optiml Design of 2-Phlnx Underctuted Finger, Intelligent Mnipultion nd Grsping, , BOLBOE, M., Theoreticl nd experimentl reserches regrding the nthropomorphic gripping systems with reduced numer of fingers, designed for roots, PhD. Thesis, University Trnsilvni of Brsov, Romni, CECCARELLI, M. et l., Design nd tests of three finger hnd with 1-DOF rticulted, Rootic Journl. V. 24, Issue 2, , DOBASHI, H. et l., Roust grsping strtegy for ssemling prts in vrious shpes, Advnced Rootics, Vol.28, Issue 15, , STARETU, I. et l., Mechnicl Hnd. Anthropomorphic Gripping Mechnism for prostheses nd roots (in Romnin), Lux Liris P.H., Brsov, Romni, CATIA 5 softwre, Reference Mnul, MOLDOVAN, C., Theoreticl nd experimentl reserches regrding the diversifiction of virtul hnd interction with ojects from virtul world with pplictions in industril engineering, PhD. Thesis, University Trnsilvni of Brsov, Romni, ACTA ELECTROTECHNICA, Volume 57, Numer 1-2, 2016, Specil Issue, ISSN