NGHIEN CJU - TRAO DOI THIET KE CHE TAO C A M BIEN DO Ll/C VA MOMEN XOAN BANG DAU DO DIEN T R DESIGN AND MANUFACTURE THE FORCE AND TORQUE SENSORS WITH STRAINGAGES Nguyln Minh Jrik, Cai Viet Anh Dung, Phan Ngoc Trich, Nguyin Viet Thang Trudng Dai hpc Su pham Ky thuat TP Ho Chi Minh TOM TAT Trong bdi bdo ndy, tdc gid mo td nhimg ky thudt cho phep chi tao cdc loai cam Men luc va cam bien mo-men bdng ddu dien tra Nhom da nghien cuu che tao thdnh cong mgch khuech dai tin hieu dien dp duac tii: cdc ddu dien tra, cUng nhu cdc cam bien luc vd mo-men xoan Cam hien luc vd cdm bien mo-men xoan duac thiet ke dua tren cdc mo phong bang phdn mem ANSYS de kiem chung ben keo cung nhu bien dgng tuang doi cua cdm bien luc (hay momen) tdc dgng tic ben ngodi len cdm bien co gid tri toi da Tir khoa: Cdm bien luc; Cdm bien momen; Mach khuech dai tin hieu ddu dien tra ABSTRACT In this paper, the authors describe the fabrication technique of force and torque sensors designed with straingages A force sensor, a torque sensor as well as a straingage signal amplificator circuit (topwcess data measured from the straingage bridge) was build and experimeted Force and torque sensor designs are based on simulation results realized on ANSYS software to test the tensile strength as well as the relative deformation of the sensor when maximum external force (or torque) is applied Keywords: Force sensor; Torque sensor; Straingage signal amplificator ISSN 0866 - 7056 TAP CHf CO KHI VIET NAM, Sd nam 2015 wwTv.cokhivietnam.vn NGHIEN CUfU-TRAO DOI Gidl THIEU cua mdt day din se tang neu nhu day hi keo gian Hmh I md ta su biln dang cua mdt sgi day dan (chieu dai L,, dudng kinh Dj) Dudi tac dung cua luc keo gian chiiu dai va dudng kinh day se trd L, va D^ nh^m bao toan thi tich cua day Mdt day dan co dudng kinh cdng nhd se ed dai lugng dien trd/chieu dai cang Idn va ngugc lai Trong Imh vuc robotics, cam bien luc md men cd the dirge su dung d cac he thdng canh tay chu - td di6u khiln tir xa, he th6ng bg xirang ngoai hay tren cac canh tay may, cho phep eae h§ thdng cd dugc chiic nang luc tirang tac giira thiet bi vdi moi trudng ben ngoai Dac biet, cac he thdng Cobot hay cac canh tay may no le thudng su dung cam biSn luc - mdmen true de phan lire - md men, qua dd cho phep \hik lap bd di8u khiSn robot theo chuyin ddng cua ngudi sir dung [3] Ci he thdng bd xuang ngoai [1] hay cac chi robot [5], cam bien lire - mdmen ed the duge su dung dl lire tuang tac giila thiet bi va chi cua ngudi sir dung, tu dd cho phep tinh toan tin hieu diSu khiln thilt bi mot each hop ly va an toan Hinh I: Bien dang chieu dai ddy ddn dudi tdc dung ciia luc keo Tren the gidi, cam bien luc, md~men ciing nhu cam biln luc-mdmen true tir lau da dugc thuang mai hda rdng rai Cac san ph4m load-cell (cam bi6n lire true) ciing da cd mat nhieu tren thi trudng Viet Nam Mot sd tac gia tren the gidi tut nghien cuu chi tao cam biln lire, md-men, dae biet la cam bien lucmomen true de phuc vu cho cac nghien cuu cua minh [4],[5] Ci Viet Nam, ciing ed mdt sd nhdm nghien ciiu da xuat ban cac cdng trinh lien quan den viee ehe tao cam bien luc, hoac cam bien md-men xoan su dung dau dien trd [ref] Trong bai bao nay, tac gia trinh bay cae nghien cuu ve phuang phap thiet ke che tao cam bien li^c va md-men xoan bang dau dien trd Cae san ph5m se cho phep, tuang lai gSn se duge su dung cac san pham robotics kl tren nham phuc vu chu yeu cho cac nghien ciiu khoa hgc ITnh vuc robotics tuong tac Vdi tinh chat vat ly tren, neu nhir ehung ta CO the dan chat mdt manh d^u dien trd len tren mdt be mat mdt vat lieu eo kha nang biln dang, ta se c6 kha nang sd dung su bien thien ciia dien trd day dan de su bien dang ciia manh vat lieu cd mdt ngoai lire tac ddng len nd Dau dien trd dugc che tao tren mdt tam phim mdng va dan len be mat cam bien theo phuang thich hgp de lire tac dung Dau dien trd cd mdt sd dac tinh nhu: Chiu anh hudng cua nhiet do, dap ling tan sd cao (do khoi lugng cua dau dien trd thudng rat nhd), chinh xac lap lai eao (khi dau thuc su dugc gan chat vao be mat cam bien tao khoi), phan giai vo Cling (chi phu thugc vao he thdng lay mau), Moi lien he giila su bien thien cua dien trd so vdi bien dang ciia day dan dugc the hien theo egng thuc sau [ref|: 1.1 Cic d3c tinh cua dau di6n trd = {(l-h2v) + C{l-2v)}y = / : y Cac ket qua thue nghiem ciing nhu ly thuylt vat ly deu chiing minh dugc rSng dien hd (1) Vdi C la h4ng sd Bridman ( c D ), v la he ' ^ ISSN 0866 - 7056 TAP CHf CO KHf VIET NAM Sd nam 2015 WW ^\ cokhivietnam.vn NGHIEN ClJfU-TRAO Ddi sd Poisson (vD o.3) K la he sd dSu va dugc vilt bdi bieu thuc: K = {\ + 2v)+C{\-2v) (2) 1.2 Nguyen ly bien dang dung cau Wheatston Do gia tri cua dien trd la nhu nhau, ta cd t h l d a t : « j = y i = ^ ^ ^ = ^ - Dudi tac diing cua biln dang tren be mat vat lieu, gia tri dien trd cua tiing straingage se thay ddi Khi dd, ta cd thi dat cac gia tri dien trd tuong ling vdi hing straingage nhu sau: Mach cku wheatston la mach dugc sii dung thu4n xuyen de do bien dang cua vat lieu vdi straingage Nguyen ly hoat dgng cua mach nhu sau: Dien ap duge giila din day tin hieu (V^va V^') duge tinh theo cdng thiie: AVs =VT-V, =E(R^+R2).iR^+R4) (4) Cl day ta cd: —'- « 0, do ed luc tac dung lam thay ddi cac gia tri dien trd cua cdc straingages, phuong trinh (18) cd the duge viet lai dudi dang sau (cac phan bac da dugc dan gian hoa): (3) E f AR-, ARA AR, AR-, i Mach cau d trang thai can bang F / = vf N I U nhu ta ehgn Rj = R^ = R^ = R^ thi ta dat bat ky dien ap nao vao maeh tren thi dien ap dau se la Luc ta ggi so dang d trang thai can bang Cdng thiic (5) duge su dung thudng xuyen viec do bien dang dan hdi eua vgt lieu bing each su dung cac dau dien hd [Hoffman] 2.Thiet ke, chi tao cam biln lire Mo hinh thiet ke cam bien lire thing triic dugc trinh bay hinh Giila thdn cam bien cd khoet mdt khe Idn theo phuang ngang, eho phep tao bien dang cd tae ddng luc ben ngoai theo phuong thang diing Hinh 3: Cdu Wheatstone Khi cd su thay ddi dien trd cua mot hay cac dien trd tr8n so vdi gia tri ban dau thi liie maeh mat can bang, liic hong mach se eo mot dien ap tuang ting d dau V^* va V^ Dien ap ed the dugc tinh nhu sau: ISSN 0866 - 7056 TAP CHf CO KHf VI$T NAM, Sd nam 2015 www.cokhivietnam.vn ^ Hinh 4: Mdu thiet ke cdm bien luc NGHIEN CUfU - TRAO Dpi Cac dau dien trd dugc dan tren mat ngoai cua than cam biln tai vi h i cd khe hd Vi tri dan nam tai cac diem cd biln dang Idn nhdt theo md phdng (xem phan kit qua md phdng trinh bay d muc IV) Cac ddu dugc ndi vdi timg cap d l tao nen cku Wheatstone So ndi chan cac straigages duoc trinh bay nhu hinh THIET KE CHE TAO CAM BIEN DO MO-MEN XOAN F Ri S+ R2 Hinh 6: Mdu thiet ke cdm bien momen Hinh 5: Sa dd ndi chdn ddu dien tra cua cdm bien luc Md hinh thiet ke cam bien mdmen xoan true dugc hinh bay hinh Cam Nguyen ly nhu sau: E+ va E- la dau bien dugc cau tao bdi phan de ed dinh hinh hon eua dipn ap khdng doi cap eho dau dien trd d vong ngoai va phan ldi di ddng ben Phan S+ va S- la cac ngd tin hieu Vs+ va Vs- (dien ldi di dgng va phan de cd dinh dugc ndi vdi ap gida dau S+ va S- va E-) lan lugt dugc bdi dam Tren dim cd khoet ranh nham tao bien dang ed md-men xoan tinh theo nguyen ly chia ap nhu sau: tac ddng len phan ldi di dpng Cac diu dien hd dugc dan hen mat ngoai cua cac dam, (E'-E-)., (6) tai vi tri chinh giila khe hd (la vi tri bien [R,.R,J' dang Idn nhat) Cac dau dien trd duge ndi vdi tung cap de tao nen cau Wheatstone So dd N I U nhu R, = R, = R3 - R^, ta cd Vs" = ndi chan cac dau dien trd dugc hinh bay nhu Vs" cam biln d trang thai nghi Khi ed mdt hong hinh luc F tac ddng tii tren xudng tao nen bien dang cho than cam biln, cae shaingages se bien dang nhu sau: R^, R^ gian (gia tri dien trd tang len) Ri ^ «, R3, R^ eo (gia tri dien trd giam) Khi do, Vs"^ > Vs' Trudng hgp luc F tac ddng tii dudi len theo phuang nguge lai, ta cd Vs* < V s Sy khac biet 4« cua gia tri dien ap chinh la tin hieu dau ' R Rj ^ eua cam biln Tin hieu se dugc khuech dai len nhilu lan trude dupe dua vao vi dieu khiln hoac may tinh Hmh 7" Sa dd ndi chdn straingages cua cdm biin md-men (- \ )( ISSN 0866-7056 TAP CHf CO KHI VIET NAM, Sd nam 2015 www.cokhivietnam.vn -0 NGHIEN C U T U - T R A O D O I Nguyen ly do: Cung gidng nhu trudng hgp cam biln luc mgt true, d day ta ed E+ va E- la diu ciia dien ap khdng ddi cap cho shaingage S+ va S- la eae ngd rin hieu Vs+ va Vs- (dien ap giira dau S+ va S- va E-) lan lugt dugc tinh theo nguyen ly chia ap nhu sau: cua kim loai ludn gan nhu tuyIn tinh ung suat nhd hon gidi han dan hdi (hinh 8), su thay ddi cua gia tri dien hd cua cac diu dien hd dan chat hen bl mat vat lieu kim loai theo lire tac ddng td ben ngoai len cam biSn cung gin nhu tuyen rinh Cac md phdng duge thuc hien vdi muc dich kiem tra bin eiing nhu biln djtng eua cam bien dudi tae ddng cua ngoai luc Myc tieu la kiem gia tri tdi da cho phep cua ngoai iE -E ) , lire (hoac mdmen) cd thi tac dung len cam biln Gia tri ling suat tdi da phai dudi ngudng gidi han dan hdi cua vat lieu, va biln dang tuong dii ciia vat lieu phai nam hong gidi ban cho phep tuong ung vdi su thay ddi tdi da cua gia tri dien Neu nhu R, = R, = Rj = R^, ta cd Vs" = trd cua dau dien hd Vs" cam bien d hang thai nghi Khi cd mdt mo-men M tac ddng vao phan loi di ddng theo 4.1 Ket qua md phdng chieu ngugc chieu kim ddng ho tao nen biln dang cho than cam bien, cac straingages se biln Nhdm nghien ciiu da thuc hien mo phdng dang nhu sau: R,, R^ gian (gia hi dien hd tang hen phan mem Ansys cam biln: Cam biln len) - R|, R^ eo (gia tri dien hd giam) Khi dd, luc va cam bien md-men xoin Vat li?u ciia Vs+ > Vs- Trudng hgp md-men M tac ddng cac cam bien dugc su dung hong cac mo phong theo chiiu ngugc lai, ta cd Vs" < Vs" Sir khac la hgp kim nhdm vdi dp bin keo 280Mpa va biet eua gia tri dien ap chinh la tin hieu diu Md-dun de Young cd gia tri 71 Gpa Kit qua m6 eua cam bien phdng cam bien luc va cam biln md-men xoSn dugc hinh bay hong hmh va hinh 10 Kit qua KETQUAMO PHONG V A T H V C NGHIEM md phdng cho thay, ddi vdi cam biln luc, tdc dyng mgt lye cd dp Idn 50 N, ung suit tdi da hen bl mat cam biln la 41.8 Mpa Cdn ddi vdi cam bien md-men, tac dung mdt md-men co Idn 12 N.m, ung suit tdi da hen bl mat cam biln la 123Mpa Cac gai tri deu nho han gia hi dp ben keo cua vat lieu cam biln Hinh 8: Sa bien dgng - ung sudt thi nghiem keo thep R^ Id giai han ddn hdi, R^ Id khd ndng chiu keo vd R^ la giai han phd hiiy cua vgt lieu Do dudng thj ung suit - biln dang Hinh P- Ket qud mo phdng cdm biin luc a) Bien dgng luang ddi; b) Ifng sudt ISSN 0866 - 7056 TAP CHI CO KHI VIET NAM, Sd nam 2015 www.cokhivietnam.vn NGHIEN CUTU - TRAO BOI lye tac dung dugc lip nguoc chieu de tao nen nglu lue (tuong duong vdi md-men xoan) tac dung len cam biln Gia tri dgc dugc tu cac shaingage se dugc khulch dai trudc gui len cdng ADC cua MCU (vi dilu khiln) MCU dugc ket ndi vdi may tinh dh luu dii lieu duge Hinh JO: Ket qud md phdng cdm bien md-men: a) Bien dgng tuang ddi; b) Ifng sudt 4.2 Ket qua thirc nghiem Hinh 12: Mo hinh thi nghiem cdm biin luc Hinh 11: Cdm bien luc vd cdm bien md-men dd dugc ddn straingages Den thdi diem hien tai, nhdm da chi tao va thu nghiem cdng cam bien lye (thiet ke theo dang dam) va cam bien md-men (thiet ke theo dang dam doi xung nhau) Tren mdi cam bien co dang straingages, cho phep tin hieu tir cau wheatston mdt each dn dinh nhat (xem hinh 11) Nhom nghien cuu da tiln hanh thuc nghiem tren cam biln lye va cam bien md-men de kiem tra tinh tuyen tinh ciia cam biln Trong thi nghiem vdi cam bien lye trye (hmh 12), nhdm sir dung mdt dong hd lye dien hi, vdi dau ket noi vdi cam bien, dau cdn lai kit ndi vdi tryc vit cho phep xoay de hieu chinh lye tae dung Cdn hong thi nghiem vdi cam biln md-men trgc (hinh 13), nhom su dung ddng hd luc dien tu ket ndi vdi cam biln true vit cho phep xoay de hieu ehinh Hinh 13: Mo hinh thi nghiem cdm hien md-men Ket qua thi nghiem cam bien lye va cam bien md-men xoan dugc trinh bay d hinh 14 va 15 Ta nhan thay mac dii co sd kit qua CO chiit lech so vdi dudng thing tuyIn tinh hda tren bieu dd, tinh tuyen tinh ciia cam biln vin hien thi kha rd rang Theo nhdm nghien cuu, eae sai so nhd den tir viec lip cac ding hd luc khong that thang hang so vdi phuong lye ein huyen Budc vit idn cung khdng eho phep thay ddi luc tac dung theo tung budc nhd Trong hrang lai, mdt he thdng thi nghiem khac vdi ehue nang hieu chinh luc ty dpng, eho kit qua ehinh xac han se duge thilt kl chi tao ^ ISSN 0866 - 7056 TAP CHf CO KHI V I £ T NAM Sd nam 2015 www.cokhivietnam.vn NGHIEN CUfU-TRAODO! Hinh 14: Kit qud thi nghiem cdm bien luc '*- trinh bay phuang an thiet ke va ch6 tao cam bien luc tinh tiln ciing nhu cam bien md-men xoin su dung diu dien hd Hai md hinh cam biln luc va md-men cdng nhu mach khuech dai tin hieu ciu wheatston da duge thiet ke va chi tao cong Tac gia sii dyng phan mIm Ansys de mo phdng kiem h a ben cua cam biln chiu tae ddng bdi lye (hoac md-men) t6i da Gia tri ling suit tdi da hen be mat cac cam biln diu nim hong ngudng gidi han dan hdi cua vat lieu dugc md phdng, dam bao chinh xac lap lai cua cam biln Kit qua thuc nghiem ciing chiing minh dugc tinh tuyen tinh ciia eae cam biln tac dyng lye (md-men xoin) hong khoang gia hi cho phep dugc dat trade Trong tuang lai, nhdm tac gia se thyc hien nghien ciiu vl phuang phap thiSt ke toi uu (vl kha nang chiu tai ciing nhu kich thudc va khdi lugng) cho cam bien luc va mo-men xoin Nghien cim ve viec che tao cam bien luc Hinh 15: Kit qud thi nghiem cdm hien md-men va md-men true ciing se dugc tien hanh Day la loai cam bien cd the dugc su dung tren cac canh tay robot cdng nghiep, nham dieu khien luc KET LUAN VA HlTbNG PHAT TRIEN tuang tac giiia canh tay may vdi moi tradng b8n Trong bai bao nay, nhdm nghiSn cuu da ngoai • Ngay nhan bai: 12/2/2015 Ngay phan bien: 18/3/2015 Tai lieu tham khao: [I] D Cai, Contribution to the study of isostatic exoskeletons for hinctional rehabilitation, application in the design of knee orthosis, Phd thesis, University of Pierre et Marie Curie, Paris, France, 2011 [2] K HofErnann, An Introduction to Shess Analysis and Transducer Design using Shain Gauges, HBM Editions [3] X Lamy, Design of an Human - Cobot Interface, Phd Thesis, University of Pierre et Mane Curie, Paris, France, 2011 [4] I, W Park, J Y Kim, S W Park, J H Oh Development of Humanoid Robot Platform KHR-2 (KAIST Humanoid Robot-2), Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, 2003 [5], J E Sanders, R A Miller, D N Berglund and S, Zachariah, A modular six-directional force sensor for prosthedc assessment, Center of Bioengineering and Department of Mechanical Engineering, University of Washmgton, 1997 Seattle ISSN 0866 - 7056 TAP CHf CO KHf VIET NAM, Sd nam 2015 ww^v.cokhivietnam.vn