Design of a Haptic Device for Teleoperation and Virtual Reality Systems

Size: px

Start display at page:

Download "Design of a Haptic Device for Teleoperation and Virtual Reality Systems"

Norah Baker
5 years ago
Views:

1 Proceedngs of the 2009 IEEE Internatonal Conference on Systems, Man, and Cybernetcs San Antono, TX, USA - October 2009 Desgn of a Haptc Devce for Teleoperaton and Vrtual Realty Systems Mehmet smet Can Dede, Özgün Selv, Tunç Blgncan Department of Mechancal Engneerng zmr Insttute of Technology zmr, Turkey candede@yte.edu.tr Yalkın Kant Department of Mechancal Engneerng Dokuz Eylül Unversty zmr, Turkey Abstract Haptcs technology has ncreased the precson and telepresence of the teleoperaton and precson of the n-house robotc applcatons by force and surface nformaton feedback. Force feedback s acheved through sendng back the pressure and force nformaton va a haptc devce as the nformaton s created or measured at the pont of nterest. In order to confgure such a system, desgn, analyss and producton processes of a haptc devce, whch s sutable for that specfc applcaton, becomes mportant. Today, haptc devces fnd use n assstve surgcal robotcs and most of the teleoperaton systems. These devces are also extensvely utlzed n smulators to tran medcal and mltary personnel. The objectve of ths work s to desgn a haptc devce wth a new structure that has the potental to ncrease the precson of the robotc operaton. Thus, lterature s revewed and possble robot manpulator desgns are nvestgated to ncrease the precson n haptcs applcatons. As a result of the nvestgatons, conceptual desgns are developed. Ultmately, fnal desgn s selected and produced after t s nvestgated n computer-aded-desgn (CAD) envronment and ts knematc and structural analyses are carred out. Keywords haptcs, robot desgn, parallel platfom manpulator, hybrd manpulator I. INTRODUCTION The sense of touch s a vable feedback to understand the envronment. Most of the tme, the sense of touch accompaned wth the vsual feedback s enough to gather most of the nformaton about a certan envronment. Ths nformaton s used by robotc nterfaces to pass the envronment data to the human operator n haptc devces. Haptc systems have been utlzed n varous state-of-the-art applcatons, such as teleoperaton systems, computer-aded-desgn (CAD), assstve robotc surgery, telesurgery, computer-aded tranngs of the mltary personnel and surgeons. In teleoperaton and telesurgery applcatons, telepresence s enhanced through haptc devces that feed back force. In tranng or smulator systems, the force nformaton s used along wth the vrtual realty nformaton to precsely smulate a real world operaton. Haptc devces employed n assstve robotc surgeres provde a precse surgcal procedure that wll mprove and shorten the healng process. Free-form modelng s possble wth the use of haptc devces n CAD. Although seral haptc manpulators have been used n a wde varety of applcatons and have large workspaces, ther relatvely low stffness and low force feedback capacty are ther weak sdes. Probably the most well known seral haptc devce s the Phantom Haptc Devce [1]. In order to ncrease stffness and force feedback capacty, parallel platform haptc manpulators have several applcatons. Joon-Woo Km et al. desgned Delta type parallel haptc devce wth one redundant actuator [2]. Masaru Uchyama et al. developed a new sx degree-of-freedom (DoF) haptc nterface. In ther work [3], they used a novel spatal gmbal fve bar mechansm for orentaton and delta manpulator for postonng. Haptcs have many applcatons for general purposes. M. Muldera et al. ntroduced haptc gas pedal for automaton sector [4]. The test results were promsng that the haptc feedback was presented to the drvers, car-followng performance was mproved. Hong Gee Sm et al. [5] emphaszed the necessty of haptc feedback n surgcal operatons and the haptc da Vnc robotc surgcal system, as presented n ther work. Haptcs s also a soluton to nanometer scale operatons. Haptcs technologes ntroduced and appled to nanotechnology applcatons n the [6, 7]. Haptc devces have also found use n medcal tranng applcatons that are accompaned wth vrtual realty nformaton. Payandeh and L [8], have nvestgated the applcaton of a low-cost electromechanc haptc technology n vrtual laparoscopc surgeres. Another vrtual realty applcaton for tranng purposes ntegrates the force-feedback nformaton from a needle wth the vrtual world n [9]. P. Wang et al. [10], have ntroduced a vrtual realty devce that produces vrtual tssue through boundary element method. In ths work, wth ts hgh precson, robustness, stffness, hgher load carryng capacty and wth three actuators located at the base, a new type of sx degree-of-freedom (DoF) hybrd haptc devce s ntroduced. It s composed of the R-Cube structure for translatonal motons and Hybrd-Sphercal structure for the orentatng the end-effector. The structural desgn of the devce was selected after examnng several conceptual desgns n CAD software envronment. In the next secton, background nformaton s provded on the exstng manpulator types and prevously developed haptc devces /09/$ IEEE 3723

Later, conceptual desgns are explaned. Then, fnal desgn selecton and ts varous analyses are descrbed. Fnally, constructed frst prototype s shown along wth the future work for mprovng the desgn. II.

2 Later, conceptual desgns are explaned. Then, fnal desgn selecton and ts varous analyses are descrbed. Fnally, constructed frst prototype s shown along wth the future work for mprovng the desgn. II. BACKGROUND As a frst step before formng the conceptual desgns, lterature s nvestgated for sutable manpulators and for ther advantages and dsadvantages. Bascally three types of manpulators can be used n desgnng of haptc devces; Seral manpulators, Parallel manpulators and Hybrd manpulators. Seral manpulators are the most common ndustral robots. They often have an anthropomorphc mechancal arm structure, whch s a seral chan of lnks, connected by jonts, formng a shoulder, an elbow, and a wrst. Ther man advantage s ther larger workspace wth respect to ther own volume and occuped floor space. Ther man dsadvantage s the low stffness nherent to an open knematc structure. Also, poston errors are accumulated from lnk to lnk. A parallel manpulator can be defned as a closed loop mechansm wth an end-effector also called as platform. In parallel manpulators, the platform of the end effector must be connected to the base at least two ndependent knematc chans where each chan contans one actuator at mnmum. Parallel manpulators have some advantages wth respect to seral manpulators such as hgher precson, robustness, stffness, and load carryng capacty. The actuators can be placed n the base platform, so that ther mass does not have to be moved, whch makes the constructon lghter and decrease the nerta of the movng parts. Ther major drawback s ther lmted workspace and low stffness n sngular postons. Hybrd manpulator can be smply defned by the combnaton of parallel and seral manpulators. Parallel parallel or parallel seral constructons can be used. They have the advantages of seral and parallel manpulators and the motons can be desgned n decoupled fashon. There are many manpulators n lterature that can meet specfcatons fro ths work. For narrowng down the research, decoupled manpulators are nvestgated where three actuators controls translatonal moton and the rest of the actuators montor orentaton whch s approprate for our task. There are three types of couplng. Strong couplng means that each pose parameter s a functon of all actuated jont varables. In complete decouplng, each pose parameter s a functon of only one actuated jont varable. Whereas n partal decouplng, partal pose parameters such as translaton and rotaton are functons of separate actuated jont varables. Partal decouplng s found n seral arms. Where translaton s obtaned by frst three actuators and orentaton s controlled by last three actuators. The advantage of usng ths type of seral manpulators s the ease n the constructon process and no recess jont s used as t s the case wth parallel platform manpulators. All jonts are actuated, but ths advantage converts to a dsadvantage n precson specfcatons because the error of each jont s accumulated. Advantages of the parallel manpulators are that the motons are partally decoupled, actuators are near to the base and precson lost are decreased because poston errors of the actuators are not added but shared. Dsadvantage s that these are hard to construct wth lots of jonts and lnks and ther work spaces are relatvely smaller. Hybrd manpulators are all self-decoupled. Usng dfferent manpulators for translaton and orentaton wll ntroduce many advantages of the seral and parallel manpulators.. For the translaton parallel manpulators wll be better because of motors are on the base. Many Cartesan robots are avalable. Some of them can be lsted as Delta, Star, Orhoglde [11] and R-Cube [12]. The dstnct manpulator n here s the R-Cube because of decoupled moton and use of revolute jonts only. However, Delta robot s a common Cartesan robot mostly used n haptc devces. The orentaton of the end-effector can be montored by seral-sphercal, hybrd-sphercal or Agle Eye [13] manpulator. Seral manpulator has the maxmum workspace and hybrd-sphercal manpulator has easer knematc calculatons wth respect to others. III. CONCEPTUAL DESIGNS In the lterature survey, possble desgns for confgurng a hgh precson haptc devce are nvestgated. As a result of the lterature survey, t s decded to acheve translatonal moton and orentaton moton separately through a hybrd structure for the robot. Therefore, the haptc devce desgn consdered n ths work s developed as two separate parts as the man body and grppng arm. Delta, Cartesan Parallel, and R-Cube manpulators are depcted for translatonal moton (man body) and for orentng the end-effector (grppng arm), Agle Eye, Hybrd-Sphercal and Seral-Sphercal manpulators are selected. A. Delta Manpulator Delta robot s a 3DoF-3RRNR parallel manpulator as shown n Fg. 1. Only three jonts are actuated. It has coupled moton wth grounded rotary actuators. It has seventeen lnk connected wth twenty-one jonts, It s easy to solve ts nverse and drect knematc analyss. Its specfcatons are hgh resoluton, easy control, avalablty of stablty under bg forces (hgh load capacty), fast cycle tme wth hgh precson wth relatvely lmted workspace. Fgure 1. Delta Manpulator 3724

B. Cartesan Parallel Manpulator Cartesan Manpulator s a 3DoF-3PRRR manpulator as shown n Fg. 2. It has decoupled moton wth grounded prsmatc actuators. It has eleven lnks connected wth twelve jonts.

R-Cube Manpulator R-Cube Manpulator s a 3DoF-3NRRR manpulator as shown n Fg. 3. It has decoupled moton wth rotary actuators placed on the ground frame.

Seral-Sphercal Manpulator Seral Sphercal Manpulator s a 3DoF-RRR manpulator wth coupled moton as shown n Fg. 2(c). It has four lnks connected wth sx jonts.

It has eght lnks connected wth nne jonts; because of ts constructon advantage t has grounded sensors., It s easy to solve for ts nverse knematc analyss.

It has four lnks connected wth sx jonts, related to ts structure t has 2 grounded and 1 floatng sensor. It s nverse knematc analyss easy to solve.

3 B. Cartesan Parallel Manpulator Cartesan Manpulator s a 3DoF-3PRRR manpulator as shown n Fg. 2. It has decoupled moton wth grounded prsmatc actuators. It has eleven lnks connected wth twelve jonts. It s relatvely easer to solve for ts nverse and drect knematc analyss. Fgure 4. Agle Eye Fgure 2. Cartesan Parallel Manpulator C. R-Cube Manpulator R-Cube Manpulator s a 3DoF-3NRRR manpulator as shown n Fg. 3. It has decoupled moton wth rotary actuators placed on the ground frame. It has seventeen lnks connected wth twenty one jonts. It s relatvely easy to solve for ts nverse and drect knematc analyss [12]. Fgure 5. Hybrd-Sphercal Manpulator F. Seral-Sphercal Manpulator Seral Sphercal Manpulator s a 3DoF-RRR manpulator wth coupled moton as shown n Fg. 2(c). It has four lnks connected wth sx jonts. Its nverse knematc analyss s complex and ts workspace s ±120 around all drectons. Fgure 3. R-Cube Manpulator D. Agle Eye Agle Eye s a 3DoF-3RRR parallel manpulator wth coupled moton as shown n Fg. 4. It has eght lnks connected wth nne jonts; because of ts constructon advantage t has grounded sensors., It s easy to solve for ts nverse knematc analyss. Its workspace s a cone wth 140 wth ±30 n torson [13]. E. Hybrd-Sphercal Manpulator Hybrd-Sphercal s a 3DoF-2RE+R Hybrd type manpulator wth decoupled moton as shown n Fg. 2(b). It has four lnks connected wth sx jonts, related to ts structure t has 2 grounded and 1 floatng sensor. It s nverse knematc analyss easy to solve. It has a workspace of ±90 (x) ±90 (y) ±120 (end effector axs). Fgure 6. IV. Seral-Sphercal Manpulator FINAL DESIGN The conceptual desgns for the two man mechansms of the haptc devce are dscussed and nvestgated n the Tables I and II. Among the man body canddates, R-cube ncludes only revolute jonts and t s relatvely smpler to manufacture both revolute jonts and the structure of ths mechansm. The decoupled moton of the R-cube and the Hybrd-Sphercal manpulators results n relatvely easy drect and nverse knematc calculatons. Thus, Hybrd-Sphercal and R-cube 3725

mechansms are selected to confgure the haptc devce. The selected mechansm has a dfferent structure than the commercally avalable systems by Force Dmenson [15].

4 mechansms are selected to confgure the haptc devce. The selected mechansm has a dfferent structure than the commercally avalable systems by Force Dmenson [15]. They use a Delta-based structure n ther systems. The producton of the fnal desgn prototype has two stages as desgn of the mechansm and the controller. Structural and knematc analyses are carred out for the mechansm as t s presented n the next subsectons. Later, n CAD envronment, mechansm desgn s fnalzed and further analyss s carred out for estmated actuator torques. TABLE I. PROPERTIES OF THE CONCEPTUAL MAIN BODY DESIGNS Delta Cartesan R-Cube # of Jonts # of Lnks Knematc Analyss Complex Smple Smple Uncoupled Moton No Yes Yes Actuaton Rotary Translatonal Rotary Grounded Actuators Yes Yes Yes Jont Types R R-P R Cost Low Medum Low TABLE II. PROPERTIES OF THE CONCEPTUAL GRIPPING ARM DESIGNS Agle Eye Hybrd- Sphercal Seral- Sphercal # of Jonts # of Lnks Knematc Partally Smple Analyss complex Complex Uncoupled Moton No Yes No Actuaton Cone 140 ±90 ±90 ±120 ±120 wth ±30 ±120 ±120 torson Grounded Actuators Yes Partally No Jont Types R R-S-E R Cost Hgh Medum Low The lnks of the haptc devce s manufactured from stanless steel wth laser cuttng. Stanless steel s selected for ts resstance to corroson and heavy loads. For the frst prototype, sldng jont archtecture s selected for ts low cost and assembly easness even though t decreases the precson. Hybrd sphercal mechansm from a manual joystck was used as the grppng arm. A custom electronc card s desgned and connected by opto-couplers aganst possble crcut faults. Card has two power supples 5V-1A and 5V 20A to overcome the fluctuaton of the voltage. Pc16f877 s chosen as the mcrocontroller due to ts capablty of handlng both dgtal and analog sgnals. Three stepper motors are mplemented for actuaton and for the locaton feedback, potentometers are used. The coordnates of the manpulator was changed to have the coordnate systems of the actuator parallel to the ground frame n order to maxmze the workspace (Fg. 7). The lnk lengths are then optmzed and tested aganst for collson n CAD. Fgure 7. Fnal Desgn A. Strutural Analyss Man body of the robot s a three DoF parallel platform manpulator. The structural propertes of the manpulator n Table III are provded usng the notaton gven n [14]. In ths table; s the degree of freedom of an unconstraned rgd body movng n the workspace of the mechansm, B s the number of moble platforms, j p s the total number of jonts on the moble platforms, c L s the total number of legs of the manpulator, L s the number of ndependent loops, f T s the sum of moblty of all jonts n the structural group. TABLE III. STRUCTURAL PROPERTIES OF THE MANIPULATOR B j p c L L f T Class Knd Type Order Modfcaton The DoF of the manpulator can be calculated usng (1) as M= (1-3)6+15=3 wth the propertes provded n Table III. M ( B C) f In ths equaton; f s the total number of jonts, C s the total number of legs, and B s the total number of movng platforms. B. Knematc Analyss In ths structure, postons of the platform are determned by the postons of the actuators. As the manpulator s an uncoupled one, moton n each axes {x,y,z} wll be dependent on only one actuator n each leg. 3726

The drect and nverse knematc analyss of the manpulator s relatvely easer due to the fact that the moton of the manpulator n each axs s uncoupled. Fg.

Note that vector p represents the changes n the poston of movng frame {E} wth respect to the fxed frame {O}.

Analyss of the system n CAD The capabltes of the system are also examned usng the mechansm analyss tools of the CAD software, SoldWorks.

5 The drect and nverse knematc analyss of the manpulator s relatvely easer due to the fact that the moton of the manpulator n each axs s uncoupled. Fg. 8 shows a coordnate relatonshp for the knematc analyss of the parallel structure. Base frame {O} and the movng frame {E} of end-effector s located as shown n Fg. 8. Note that vector p represents the changes n the poston of movng frame {E} wth respect to the fxed frame {O}. The parameters h and l are the dstance of ground jont to ground frame {O} coordnate center and the length of the actuated lnk respectvely. C. Analyss of the system n CAD The capabltes of the system are also examned usng the mechansm analyss tools of the CAD software, SoldWorks. A predefned path trajectory s provded to the actuated jonts of the devce to trace the sdes of a cube wth a reasonable velocty profle (a trapezodal velocty profle for each drecton). The velocty, acceleraton and actuator torque profles are nvestgated as a result of the examnaton. The requred actuator torques are shown n the Fg Fgure 9. Torque Profle of Actuator 2 Actuator 2 torque profle fluctuates about -91 and -151 N.mm as observed n Fg. 9. Fgure 8. Analyss of the Fnal Desgn Vector p can be represented n terms of the unt vectors of the ground frame as shown n (2). p Pu P u P u3 Forward knematc soluton s presented n (3). ; 1,2, 3 P h l sn The velocty components of the platform s calculated as shown n (4). Fgure 10. Torque Profle of Actuator 1 Actuator 2 torque profle fluctuates about -66 and 15 N.mm as observed n Fg. 10. V l ; 1,2, 3 cos The nverse knematc soluton of the manpulator s gven n (5). Usng ths equaton, t s possble to calculate the requred poston of the actuators for a desred end-effector poston. cos P h sn 1,2, l sn ; 1 arctan 2 sn, cos Fgure 11. Torque Profle of Actuator 3 Actuator 2 torque profle fluctuates about 17 and -37 N.mm as observed n Fg. 11. As t s expected, the hghest mean torque ratng s observed n actuator 2, whch s responsble for the moton along the z-axs. The second actuator s under the 3727

constant gravtatonal loadng. It s not sharng ths load wth the other actuator as expected from a parallel platform manpulator due to ts changed orentaton to ncrease the workspace. V.

6 constant gravtatonal loadng. It s not sharng ths load wth the other actuator as expected from a parallel platform manpulator due to ts changed orentaton to ncrease the workspace. V. CONCLUSION Force and surface nformaton feedback s requred for varous robotc applcatons to ncrease precson and telepresence. Haptc devces are ncreasngly utlzed for ths purpose n ndustral applcatons and scentfc studes. Mechansm and controller desgns and producton are mportant n these systems n whch precson s vtal. In ths work, t s amed to confgure a new robot structure to be used n haptc systems that wll ntroduce some mprovements. In that respect, drect drve jonts are used, mechansms that enable uncoupled moton are selected and R- Cube mechansm s twsted to enlarge the workspace (Fg. 12). However, the CAD analyss ndcates that the change n the orentaton of the R-Cube results n hgher loadng n one of the actuators of the system. Thus, for the second prototype, R-Cube mechansm wll be constructed n ts orgnal orentaton. Further nvestgaton on the mechansm wll be made durng the desgn and constructon phase of the second prototype. Fgure 12. Frst Workng Prototype It s planned to use bearngs nstead of sldng jonts to ncrease the precson. Also, t s necessary to change the stepper motors used n the frst prototype wth powerful servomotors to enable the system to be used as a haptc devce. System wll be examned n a vrtual realty smulator after the planned modfcatons and the hybrd archtecture are acheved. REFERENCES [1] O. Thomas H. Masse and J. K. Salsbury, The PHANTOM Haptc Interface: A Devce for Probng Vrtual, Amercan Socety of Mechancal Engneers, Dynamc Systems and Control Dvson DSC, Vol. 55-1, pp Nov [2] Joon-Woo Km, Duk-Hee Park, Han-Sung Km, Sung-Hyun Han, Desgn of a Novel 3-DOF Parallel-type Haptc Devce wth Redundant Actuaton, Control, Automaton and Systems, Oct. 2007, [3] Masaru Uchyama, Yuch Tsumak, and Woo-Keun Yoon, Desgn of a Compact 6-DOF Haptc Devce to Use Parallel Mechansms, Sprnger Tracks n Advanced Robotcs, Sprnger Berln / Hedelberg, Volume 28, 2007, [4] M. Muldera, M.M. Van Paassena and D.A. Abbnk, Haptc gas pedal feedback, Ergonomcs, vol 51 (ssue 11),2008-Nov, pp [5] Hong Gee Sm, Sdney Kam Hung Yp, Chrstopher Wa Sam Cheng, Equpment and technology n surgcal robotcs, World Journal of Urology, Sprnger Berln / Hedelberg, Volume 24, Number 2, June, 2006, pp [6] F.J. Rubo-Serra, R.W. Stark, S. Thalhammer, W.M. Heckl, Forcefeedback joystck as a low-cost haptc nterface for an atomc-forcemcroscopy nanomanpulator, Appled Physcs A: Materals Scence & Processng, Sprnger Berln / Hedelberg, Volume 76, Number 6, Aprl 2003, pp [7] Marc Jobn, Raphael Foscha, Sébasten Grange, Charles Baur, Gérard Gremaud, Kyumn Lee, Laszlo Forró, and Andrzej Kulk, Versatle force feedback manpulator for nanotechnology applcatons, Revew of Scentfc Instruments, Volume 76 Issue 5, [8] Shahram Payandeh, Teme L, Toward new desgns of haptc devces for mnmally nvasve surgery, Internatonal Congress Seres Computer Asssted Radology and Surgery. Proceedngs of the 17th Internatonal Congress and Exhbton, June 2003, [9] Franck P. Vdala, Ncholas Chalmers, Derek A. Gould, Andrew E. Healey, Ngel W. Johna, Developng a needle gudance vrtual envronment wth patent-specfc data and force feedback, Internatonal Congress Seres Computer Asssted Radology and Surgery, May 2005, [10] P. Wang, A.A. Becker, I.A. Jones, A.T. Glover, S.D. Benford, C.M. Greenhalgh, M. Vloeberghs, A vrtual realty surgery smulaton of cuttng and retracton n neurosurgery wth force-feedback, Computer methods and programs n bomedcne, vol. 84, 2006, [11] A. Pashkevch, P. Wenger, D. Chablat, Desgn strateges for the geometrc synthess of Orthoglde-type mechansms, Mechansm and machne theory, Elsever, Oxford, vol. 40, ROYAUME-UNI, 2005, pp [12] Wemn L, Feng Gao, Janjun Zhang, R-CUBE, a decoupled parallel manpulator only wth revolute jonts, Mechansm and Machne Theory, Elsever, Volume 40, Issue 4, Aprl 2005, pp [13] Gosseln CM, StPerre E, Gagne M, On the development of the Agle Eye, Robotcs & Automaton Magazne, IEEE, vol. 3, Issue 4, Dec 1996, pp [14] Rasm I Alzade, Ça da Bayram, Structural Synthess of parallel manpulators, IFToMM J. Mech. Mach. Theory, Vol. 39, 2004, [15] Force Dmenson. Retreved June 20, 2009 from

Inverse kinematic Modeling of 3RRR Parallel Robot

Inverse kinematic Modeling of 3RRR Parallel Robot ème Congrès Franças de Mécanque Lyon, 4 au 8 Août 5 Inverse knematc Modelng of RRR Parallel Robot Ouafae HAMDOUN, Fatma Zahra BAGHLI, Larb EL BAKKALI Modelng and Smulaton of Mechancal Systems Laboratory,