NGHIEN CJU - TRAO DOI THIET KE CHE TAO C A M BIEN DO Ll/C VA MOMEN XOAN BANG DAU DO DIEN T R 6 DESIGN AND MANUFACTURE THE FORCE AND TORQUE SENSORS WITH STRAINGAGES Nguyln Minh Jrik,
Trang 1NGHIEN CJU - TRAO DOI
THIET KE CHE TAO C A M BIEN DO Ll/C VA MOMEN XOAN
BANG DAU DO DIEN T R 6
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 do dien tra Nhom da nghien cuu che tao thdnh cong mgch khuech dai tin hieu dien dp do duac tii: cdc ddu do dien tra, cUng nhu cdc cam bien do luc vd mo-men xoan Cam hien do luc vd cdm bien do mo-men xoan duac thiet ke dua tren cdc mo phong bang phdn mem ANSYS de kiem chung do ben keo cung nhu bien dgng tuang doi cua cdm bien khi 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 do 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
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Trang 2NGHIEN CUfU-TRAO D O I
1 Gidl THIEU
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 nay cd dugc chiic nang do 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
6 true de do 6 thanh 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 do 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
Tren the gidi, cam bien do luc, md~men
ciing nhu cam biln luc-mdmen 6 true tir lau da
dugc thuang mai hda rdng rai Cac san ph4m
load-cell (cam bi6n do lire 1 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
do lire, md-men, dae biet la cam bien do
luc-momen 6 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
do md-men xoan su dung dau do dien trd [ref]
Trong bai bao nay, tac gia trinh bay cae nghien
cuu ve phuang phap thiet ke che tao cam bien do
li^c va md-men xoan bang dau do dien trd Cae
san ph5m nay se cho phep, trong tuang lai gSn
se duge su dung trong cac san pham robotics kl
tren nham phuc vu chu yeu cho cac nghien ciiu
khoa hgc trong ITnh vuc robotics tuong tac
1.1 Cic d3c tinh cua dau do di6n trd
Cac ket qua thue nghiem ciing nhu ly
thuylt vat ly deu chiing minh dugc rSng dien hd
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 thanh 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
Hinh I: Bien dang chieu dai ddy ddn dudi tdc dung
ciia luc keo
Vdi tinh chat vat ly tren, neu nhir ehung
ta CO the dan chat mdt manh d^u do 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 do su bien dang ciia manh vat lieu khi cd mdt ngoai lire tac ddng len nd Dau do dien trd dugc che tao tren mdt tam phim mdng va dan len be mat cam bien theo phuang thich hgp de do lire tac dung Dau do dien trd cd mdt sd dac tinh nhu: Chiu anh hudng cua nhiet
do, dap ling tan sd cao (do khoi lugng cua dau
do dien trd thudng rat nhd), do chinh xac lap lai eao (khi dau do thuc su dugc gan chat vao be mat cam bien tao thanh 1 khoi), do phan giai vo Cling (chi phu thugc vao he thdng lay mau), Moi lien he giila su bien thien cua dien trd so vdi do bien dang ciia day dan dugc the hien theo egng thuc sau [ref|:
= {(l-h2v) + C{l-2v)}y = / : y (1)
Vdi C la h4ng sd Bridman ( c D 1 ), v la he ' ^
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Trang 3NGHIEN ClJfU-TRAO Ddi
sd Poisson (vD o.3) K la he sd dSu do va dugc
vilt bdi bieu thuc:
K = {\ + 2v)+C{\-2v) (2)
1.2 Nguyen ly do bien dang dung cau
Wheatston
Mach cku wheatston la mach dugc sii
dung thu4n xuyen de do do bien dang cua vat
lieu vdi straingage Nguyen ly hoat dgng cua
mach nhu sau:
Dien ap do duge giila 2 din day tin hieu
V^') duge tinh theo cdng thiie:
Do gia tri cua 4 dien trd la nhu nhau, ta
cd t h l d a t : « j = y i 2 = ^ ^ ^ 4 = ^ - 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:
(V^va
AVs = VT-V,
=E-(R^+R2).iR^+R4)
(3)
Mach cau d trang thai can bang khi
F / = vf N I U nhu ta ehgn Rj = R^ = R^ = R^ thi
khi ta dat bat ky dien ap nao vao maeh tren thi
dien ap dau ra se la 0 Luc nay ta ggi so do dang
d trang thai can bang
(4)
Cl day ta cd: —'- « 0 , do do khi 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 thanh phan bac 2 da dugc dan gian hoa):
E f AR-, ARA AR, AR-, i
Cdng thiic (5) duge su dung thudng xuyen trong viec do do bien dang dan hdi eua vgt lieu bing each su dung cac dau do dien hd [Hoffman]
2.Thiet ke, chi tao cam biln do lire
Mo hinh thiet ke cam bien do lire thing 1 triic dugc trinh bay trong hinh 4 Giila thdn cam bien cd khoet mdt khe Idn theo phuang ngang, eho phep tao bien dang khi 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 nay
maeh mat can bang, liic nay hong mach se eo
mot dien ap tuang ting d dau ra V^* va V^ Dien
ap nay ed the dugc tinh nhu sau:
^
Hinh 4: Mdu thiet ke cdm bien luc
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Trang 4NGHIEN CUfU - TRAO Dpi
Cac dau do dien trd dugc dan tren 2 mat
ngoai cua than cam biln tai vi h i cd khe hd Vi
tri dan nam tai cac diem cd do biln dang Idn nhdt
theo md phdng (xem phan kit qua md phdng
trinh bay d muc IV) Cac ddu do nay dugc ndi
vdi nhau timg cap 1 d l tao nen cku Wheatstone
So do ndi chan cac straigages duoc trinh bay
nhu trong hinh 5
F
Ri S+ R2
Hinh 5: Sa dd ndi chdn ddu do dien tra
cua cdm bien luc
Nguyen ly do nhu sau: E+ va E- la 2 dau
eua dipn ap khdng doi cap eho dau do dien trd
S+ va S- la cac ngd ra tin hieu Vs+ va Vs- (dien
ap do gida 2 dau ra S+ va S- va E-) lan lugt dugc
tinh theo nguyen ly chia ap nhu sau:
(E'-E-).,
[R,.R,J' (6)
N I U nhu R, = R, = R3 - R^, ta cd Vs" =
Vs" khi cam biln d trang thai nghi Khi ed mdt
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)
-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
cua 2 gia tri dien ap nay chinh la tin hieu dau
ra eua cam biln Tin hieu nay se dugc khuech
dai len nhilu lan trude khi dupe dua vao vi dieu
khiln hoac may tinh
3 T H I E T KE CHE TAO CAM BIEN DO MO-MEN XOAN
Hinh 6: Mdu thiet ke cdm bien momen
Md hinh thiet ke cam bien do mdmen xoan 1 true dugc hinh bay trong hinh 6 Cam bien dugc cau tao bdi phan de ed dinh hinh hon
d vong ngoai va phan ldi di ddng ben trong Phan ldi di dgng va phan de cd dinh dugc ndi vdi nhau bdi 2 thanh dam Tren 2 thanh dim cd khoet 2 ranh nham tao bien dang khi ed md-men xoan tac ddng len phan ldi di dpng Cac diu do dien
h d dugc dan hen 2 mat ngoai cua cac thanh dam, ngay tai vi tri chinh giila khe hd (la vi tri do bien dang Idn nhat) Cac dau do dien trd duge ndi vdi nhau tung cap 1 de tao nen cau Wheatstone So dd ndi chan cac dau do dien trd dugc hinh bay nhu hong hinh 7
(
-Ri
\
Rj ^
^ «,
)(
' R -0 4«
Hmh 7" Sa dd ndi chdn straingages cua cdm biin
md-men
ISSN 0866-7056 TAP CHf CO KHI VIET NAM, Sd 3 nam 2015
Trang 5Nguyen ly do: Cung gidng nhu trudng
hgp cam biln luc mgt true, d day ta ed E+ va
E- la 2 diu ciia dien ap khdng ddi cap cho
shain-gage S+ va S- la eae ngd ra rin hieu Vs+ va
Vs- (dien ap do giira 2 dau ra S+ va S- va E-) lan
lugt dugc tinh theo nguyen ly chia ap nhu sau:
iE -E ) ,
Neu nhu R, = R, = Rj = R^, ta cd Vs" =
Vs" khi cam bien d hang thai nghi Khi cd mdt
mo-men M tac ddng vao phan loi di ddng theo
chieu ngugc chieu kim ddng ho tao nen biln
dang cho than cam bien, cac straingages se biln
dang nhu sau: R,, R^ gian (gia hi dien hd tang
len) - R|, R^ eo (gia tri dien hd giam) Khi dd,
Vs+ > Vs- Trudng hgp md-men M tac ddng
theo chiiu ngugc lai, ta cd Vs" < Vs" Sir khac
biet eua 2 gia tri dien ap nay chinh la tin hieu diu
ra eua cam bien
4 KETQUAMO PHONG V A T H V C NGHIEM
Hinh 8: Sa do bien dgng - ung sudt trong 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 do thj ung suit - biln dang
cua kim loai ludn gan nhu tuyIn tinh khi ung suat nhd hon gidi han dan hdi (hinh 8), su thay ddi cua gia tri dien hd cua cac diu do 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 do bin eiing nhu biln djtng eua cam bien dudi tae ddng cua ngoai luc Myc tieu la kiem ha gia tri tdi da cho phep cua ngoai 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 do 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 trd cua dau do dien hd
4.1 Ket qua md phdng Nhdm nghien ciiu da thuc hien mo phdng hen phan mem Ansys 2 cam biln: Cam biln do luc va cam bien do md-men xoin Vat li?u ciia cac cam bien dugc su dung hong cac mo phong nay la hgp kim nhdm vdi dp bin keo 280Mpa va Md-dun de Young cd gia tri 71 Gpa Kit qua m6 phdng cam bien luc va cam biln md-men xoSn dugc hinh bay hong hmh 9 va hinh 10 Kit qua
md phdng cho thay, ddi vdi cam biln luc, khi 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, khi tac dung mdt md-men co do Idn 12 N.m, ung suit tdi da hen bl mat cam biln
la 123Mpa Cac gai tri nay deu nho han gia hi dp ben keo cua vat lieu cam biln
Hinh P- Ket qud mo phdng cdm biin luc a) Bien dgng luang ddi; b) Ifng sudt
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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 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 thanh cdng cam bien do lye (thiet
ke theo dang thanh dam) va cam bien do md-men
(thiet ke theo dang 2 thanh dam doi xung nhau)
Tren mdi cam bien co dang 4 straingages, cho
phep do 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 2
cam biln nay Trong thi nghiem vdi cam bien lye
1 trye (hmh 12), nhdm sir dung mdt dong hd do
lye dien hi, vdi 1 dau ket noi vdi cam bien, dau
cdn lai kit ndi vdi 1 tryc vit cho phep xoay de
hieu chinh lye tae dung Cdn hong thi nghiem
vdi cam biln md-men 1 trgc (hinh 13), nhom
su dung 2 ddng hd do luc dien tu ket ndi vdi
cam biln 2 true vit cho phep xoay de hieu ehinh
lye tac dung dugc lip nguoc chieu nhau de tao nen 1 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 khi gui len cdng ADC cua MCU (vi dilu khiln) MCU dugc
ket ndi vdi may tinh dh luu dii lieu do duge
Hinh 12: Mo hinh thi nghiem do cdm biin luc
Hinh 13: Mo hinh thi nghiem do cdm hien md-men
Ket qua thi nghiem do cam bien lye va cam bien md-men xoan dugc trinh bay d hinh
14 va 15 Ta nhan thay mac dii co 1 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 nay den tir viec lip cac d i n g hd do 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 k l chi tao ^
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Trang 7NGHIEN CUfU-TRAODO!
Hinh 14: Kit qud thi nghiem do cdm bien luc
' * -
Hinh 15: Kit qud thi nghiem do cdm hien md-men
5 KET LUAN VA HlTbNG PHAT TRIEN
Trong bai bao nay, nhdm nghiSn cuu da
trinh bay phuang an thiet ke va ch6 tao cam bien
do luc tinh tiln ciing nhu cam bien do md-men xoin su dung diu do dien hd Hai md hinh cam biln do luc va md-men cdng nhu mach khuech dai tin hieu ciu wheatston da duge thiet ke va chi tao thanh cong Tac gia sii dyng phan mIm Ansys de mo phdng kiem h a do ben cua cam biln khi 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 do chinh xac lap lai cua cam biln Kit qua thuc nghiem ciing chiing minh dugc tinh tuyen tinh ciia eae cam biln nay khi tac dyng lye (md-men xoin) hong khoang gia hi cho phep dugc dat ra trade Trong tuang lai, nhdm tac gia se thyc hien nghien ciiu v l 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
va md-men 6 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 tuang tac giiia canh tay may vdi moi tradng b8n 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
(KAI-ST 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
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