Development of Intelligent Robot Hand using Proximity, Contact and Slip sensing

Transcription

1 21 IEEE Intenational Confeence on Robotics and Automation Anchoage Convention Distict May 3-8, 21, Anchoage, Alaska, USA Development of Intelligent Robot Hand using Poximity, Contact and Slip sensing Hioaki Hasegawa* 1, Yoshitomo Mizoguchi* 2, Kenjio tadakuma* 3, Aiguo Ming* 1, Masatoshi Ishikawa* 4 and Makoto Shimojo* 1 Abstact To achieve the skillful task like the human, many eseaches have been woking on obot hand. An inteaction with vision and tactile infomation ae indispensable fo ealization of skillful tasks. In the existing eseach, the method using a camea to get the vision infomation is often found. But, in the bounday aea of a non-contact phase and a contact phase, thee ae poblem that lack of senso infomation because the influence of occlusion comes up to suface. We devise to intoduce the poximity senso in this aea. And we call the obot hand which is equipped with poximity, tactile and slip senso intelligent obot hand. In this eseach, we show the constitution example of the intelligent obot hand and popose the method to ealize Pick&Place as concete task. I. INTRODUCTION In ecent yeas, the engineeed epoduction of dexteous finges simila to those of the human hand has been tageted, and eseach elating to obot hands has been enthusiastically caied out. In the ealization of skillful opeations by means of this hand, the employment of visual and tactile infomation is indispensible. By way of existing applications of visual infomation, Namiki et al.[1][2] used high-speed vision and implemented a seies of opeations fom appoach to the taget object to gasping it, and futhe showed that visual infomation is effective fo gasp/manipulation opeations by pefoming tasks such as the manipulation of tools and the tying of sting. Howeve, in the case a camea is used fo the acquisition of visual infomation, thee is an issue of infomation lacking in the egion whee the sepaation of the hand and taget object is exceedingly small due to concealment, etc. A method used in esponse to this issue is a poximity senso to detect shot distances of a few centimetes fom the contact suface[3] [4]. A faste appoach and softe contact is made possible by eliably detecting shot distances accoding to a poximity sense. Meanwhile, position and foce of contact and detection of slippage ae impotant as tactile infomation. Many poposals have been made fo tactile sensos that detect position and stength of contact[5][6]. Howeve, the impotant point in a *1 Depatment of Mechanical Engineeing and Intelligent Systems, the Univesity of Electo-Communications, Chofugaoka, Chofu-shi, Tokyo, Japan *2 Hamonic Dive Systems Inc. *3 Depatment of Mechanical Engineeing, Gaduate School of Engineeing, Osaka Univesity, 2-1 Yamadaoka, Suita, , Japan *4 Depatment of Infomation Physics and Computing, Gaduate School of Infomation Science and Technology, The Univesity of Tokyo, Hongo, Bunkyo-ku, Tokyo , Japan pactical application is the teatment of the wiing fom the senso and high-speed esponsiveness. The minimization of wiing is paticulaly necessay when sensos ae installed in confined pats such as the fingetips. Also, a esponse speed of within 1ms is desiable in the 1kHz contol loop used fo obot contol in ode to facilitate esponsiveness. In the application of tactile infomation to hand contol, thee ae such examples as the high-speed otation contol of a pen-shaped object by a thee-fingeed hand with a senso that could apidly detect contact infomation, as achieved by Ishihaa et al.[7], and the gasping of objects of unknown fiction coefficient and vaying weights using a slip senso and slip contol, as achieved by Gunji et al.[11] Now, we believe that an integated system of visual, poximity, tactile and slip senso goups as shown in Fig.1 is essential in the ealization of high-speed handling by a obot hand. Howeve, thee is nothing in the way of eseach concening integated systems of visual, poximity, tactile and slip senso goups with the exception of that by Shimoyama et al.[8] They embedded an ulta-small theeaxis tactile senso and a poximity senso, etc. on a gippetype hand and caied out handling of tablewae as an example of handling in coodination with visual infomation. The position of the object was visually estimated with gasp diection adjustments in the vicinity of the object caied out next by a poximity senso. Afte contact, slip contol, etc. of the gasped object was caied out by the thee-axis tactile senso, but since thee is no epot on the entie system as yet, the details ae not clealy known. As in this example, the gasping, tanspotation and placement of the object ae fundamental gasp opeations pefomed by a obot hand. In addition to each pocess of gasping, tanspotation and placement, pocesses that Fig. 1. Global Vision Poximity Local Tactile Slip Noncontact Poximity Contact Poposal System Poposed senso configuation fo a obot hand /1/$ IEEE 777

2 establish the gasp (i.e. the appoach to the taget object and gasp attitude contol) ae necessay. On this occasion, we also consideed the abovementioned gasping, tanspotation and placement as examples of fundamental opeations fo high-speed handling by a obotic hand. Fo example, object position infomation is necessay in ode to gasp and can be measued by standad vision, but eo exists and measuement is not possible at shot distances due to concealment of the object. Fo this eason, it is necessay to pefom safe and eliable gasping though using a poximity sense at shot distances. Also, configuation of the gasp stength in accodance with the object is necessay when gasping. If the gasp stength is excessive, it will esult in damage to the object o oveloading of the engine. If it is insufficient, the taget object will be dopped. Fo this eason, it is necessay to implement a gasp stength that does not let the object slip and dop and yet is as small as possible. Next, the pevention of the taget object falling, etc. by appopiate gasp stength contol is essential in the same way as in both the tanspot and placement pocesses, as vaious intefeences such as inetia foces and vibations incease duing tanspotation. In the final placement opeation, it is necessay to aest the slippage geneated fom the contact between the floo and the object, and elease the object in ode to avoid the dange of pushing the object into the floo o dopping it. We have aleady developed a net-stuctue poximity senso and tactile and slip sensos. These sensos all have a esponsiveness of within 1ms as they have the educed wiing of 6 wies o less and ae analogue cicuity netwoks. In this eseach, we seamlessly detect fom poximity to contact and achieve a safe and eliable gasp though the integation of senso goups with these chaacteistics in a thee-fingeed hand, and popose an appopiate gasp stength contol deived fom slippage infomation duing gasping, tanspot and placement pocesses. Robot hands possessing this kind of senso goup and faculty ae called intelligent obot hands. Futhemoe, object placement was visually estimated and handled using the poximity, tactile and slip sense infomation shown in Fig.1. In this aticle, we descibe the system stuctue of an intelligent obot hand and expeimental esults elating to the fundamental opeations of appoach, gasp attitude, tanspotation and placement caied out using this system. II. TACTILE/SLIP/PROXIMITY INTEGRATED SENSOR In this section we descibe the senso used in the obot hand and the method of mounting in the hand. A. Tactile/Slip/Poximity Integated Senso The senso employed was a cente of pessue type tactile senso (CoP senso)[9].this senso is a thee-laye stuctue composed of a laye of pessue sensitive conductive ubbe inseted between two layes of conductive film. It outputs the cental position of the load distibution applied to the senso and the sum total of that foce. As it is composed of soft mateial, it is possible to mount by wapping aound the fingetip. Also, in addition to possessing high-speed esponsiveness of 1ms, it also has the featue of educed wiing, with just fou wies, egadless of senso suface aea. This senso eacts to the foce tangential to the senso [1]. Expeimental esults ae shown in Fig.2.The uppe gaph shows CoP senso foce output, the middle gaph shows object displacement and the lowe gaph shows the foce in the tangential diection measued by the load cell. In the diagam, the sudden decline of the senso foce output accompanying the incease of the tangential foce can be seen in egion II. Slippage pediction/detection is caied out accoding to this. The following two conditions ae intoduced as slippage detection conditions. In the case eithe of these conditions is fulfilled, the system judges slippage have occued.[11]. Condition 1: V > V th (1) OR Condition 2: d V < c (2) dt Hee, V is the decline in senso foce output fom that of static state. And V th and c ae thesholds. B. Net-stuctue Poximity Senso The poximity senso used was a net-stuctue poximity senso we developed[12][13]. Fig.3 shows its stuctue. The senso uses photo-eflectos as detection elements.the photoeflecto is composed of a luminescent infaed LED and a phototansisto as infaed detecto.infaed ays fom LEDs eflect on the suface of object, then phototansistos detect and tansfom them into cuents.reflected IRs decline as detecting object is distant, so output of elements ae appoximately invesely popotional to distance. Senso Foce Output (V) Lase Displecement Mete Output (mm) Tangential Foce (N) I II III V time (ms) Fig. 2. Tangential foce chaacteistic of the CoP senso. Initially, CoP senso is pessed at constant foce. In egion II, tangential foce is inceasing, then senso output dops by V. And duing slippage (egion III), the stickslip between senso and suface of objecgt makes senso output vibational. 778

3 3 Senso Output Pess Point E3 Led dive 25 2 E1 esisto netwok laye E4 Fig. 3. Led dive photo eflecto E2 Stuctue of the net-stuctue poximity senso The senso stuctue is such that the node intevals of the 2-laye m n esistance matix ae connected by phototansistos. Thee ae output lines fom the matix fo each of the fou nodes E1, E2, E3, E4 and two to dive the luminescent LED, giving a total of just six wies. Also, the senso is an analogue cicuity netwok and so has the chaacteistic of an almost constant esponse speed independent of numbe and placement of detection elements and of senso suface aea. The senso outputs the cental position of the illuminance distibution poduced when infaed light fom the luminescent LED is eflected by the taget object and the sum total of said illuminance. Unless especially heteomophous objects ae tageted, the cental position of the illuminance distibution shows the 2-dimensional cental position of the taget object on the senso suface and the sum total of the illuminance coesponds to the distance between the taget object and senso suface. C. Realization of Integated Tactile/Poximity Senso As it is necessay fo both the tactile senso and poximity senso to be on the hand suface in ode to make measuements duing the appoach until contact with the taget object fom the same suface, the geometic aangement of the sensos becomes an issue. In esponse, we devised a method using a CoP senso with a though-hole established. The coexistence of both sensos was devised by establishing a though-hole in the CoP senso as shown in Fig.6, and exposing the eceptive suface of the poximity senso by this apetue. Fo this eason, it is necessay to investigate the change in chaacteistics of the CoP senso due to this thoughhole pocessing. Accodingly, position and load output was measued fo the case when a 6-mm hole was made in the cente of the CoP senso (6mm 3mm).The position output esults ae shown in Fig.4.The position output test measued the senso output fo the case whee pessue was applied to the punched CoP senso at 5-mm intevals fom the edge. It can be seen fom Fig.4 that position output in the vicinity of the though-hole is displaced adially outwads fom the hole. Howeve, this eo is aound 2mm at maximum and so insignificant. It was also veified that thee was almost no dispaity in the load output. y[mm] Hole x[mm] Fig. 4. Position output chaacteistic of the CoP senso with the hole. Pessed at evey 5-mm intevals (blue plot), the position outputs of the senso (magenta) is deiplaced outwads fom the hole III. CONFIGURATION OF THE INTELLIGENT ROBOT HAND Fig.5 shows an image of the entie system. A theefingeed hand with eight degees of feedom (manufactued by Hamonic Dive Systems) was used fo a platfom on which to compose the obot hand. The hand was mounted on an XZ stage to give a configuation of one degee of feedom in both the vetical and hoizontal diections. A complete image of the hand is shown in Fig.6.Poximity, tactile and slip sensos ae mounted on each fingetip and the matix-stuctue poximity senso on the palm. ART-Linux was employed fo the contol OS and a 1-ms contol loop implemented. A. Configuation of the Fingetips In mounting an integated tactile and poximity senso in a small pat such as a fingetip, a photo eflecto RPR- 22 (manufactued by ROHM) of long detection ange was employed as the detection element with just one element installed in each tip. The poximity senso element was embedded in the fingetip pio to molding fom two-liquid type had uethane esin. Holes 6mm in diamete wee established in coesponding positions on the CoP sensos, Counte bod Encode Signal D/A bod Contol Signal Contol PC Fig. 5. A/D bod Senso Output Encode Signal Contol Signal Senso Output Analog Cicuit Senso Output Robot Hand + XZ Stage Z Stage X Stage Moto Dive Moto Dive Hand Moto Dive Encode Signal Contol Signal Outline of the intelligent hand system 779

4 .8.7 Tactile-Poximity Senso Net-stuctue PoximitySenso Senso Distance Output (V) IR Filte Non Cove Distance(mm) Fig. 6. Intelligent hand with poximity and tactile sensos Fig. 7. Distance output chaacteistic of the palm s poximity senso.5 and they wee mounted on the fingetips. Also, the senso suface was coveed by a potective mesh. B. Configuation of the Palm Poximity Senso An RPR-22 identical to that used in the fingetips was used fo the net-stuctue poximity senso mounted in the palm and was a 3 5 matix configuation. The esistance between elements, which is a cicuit constant, and selection of the extenal esistance was measued using a cicuit simulato. The sensos wee aanged on a pinted cicuit boad as shown in Fig.6, and the space between senso elements plugged with uethane esin. The entie senso suface was given a potective IR filte coveing. Due to this the functionality as a palm, contact suface could be peseved. The manufactued senso chaacteistic test esults ae shown in Figs.7 and 8. In the test, a cicula-shaped white piece of pape was placed diectly in font of the senso topleft element and the output measued fom a stat condition of contact to a point of sepaation. It can be seen fom Fig.7 that the senso sepaation output is a wavefom possessing one peak. This is a eflection of the chaacteistics of the poximity senso element. Meanwhile, as shown in Fig. 8, the senso position output becomes lage in the vicinity of the focal length and is asymptotic to the cente as sepaation inceases. At close distances the senso output tends to the object position as the senso outputs the cental position of the eflected light distibution. Howeve, in accodance with an incease in sepaation, the eflected light incident on the senso suface becomes unifom as the light eflected fom the object diffuses and the senso output becomes asymptotic to the cente position. Also, the position and distance outputs both decline in the case the senso is coveed by the IR filte. IV. PICK & PLACE BY THE ROBOT HAND The Pick & Place opeation was implemented as a specific task using the hand unde the conditions of 1) the taget object weight/shape/fiction conditions ae unknown, and 2) an installation eo exists. In ode to fulfill; the task unde these conditions, a gasping stategy with each of the following pocesses was adopted accoding to the following kind of opeation pimitive combination 1) Appoach: Placement Fig. 8. Senso Distance Output (V) Y_position X_position Y IR Filte X IR Filte Y Non Cove X Non Cove Distance(mm) Position output chaacteistic of the palm s poximity senso eo handling by palm poximity senso. 2) Gasp attitude contol: fingetip contact timing by fingetip poximity sense. 3) Gasping/tanspotation/placement: Placement based on anti-slip contol and slip detection by tactile and slip sensos. The details ae descibed below. A. Handling of Placement Eo by Palm Poximity Senso As an initial appoach opeation, handling is caied out fo the case the object is displaced fom the assumed position. The object position is estimated by sight if the obot has such a sense, o a position is specified if the obot is pat of an assembly pocess in a factoy. Howeve, to conside that a position eo exists is standad in eithe case. It is theefoe desiable to absob this placement eo with a eliable and safe gasp. On this occasion, this opeation was caied out by the net-stuctue poximity senso attached to the palm of the hand. The issue hee is that the senso depends on the suface popeties of the taget object as it utilizes infaed light eflection. Accodingly, this issue was dealt with by the following method. Fistly, the senso distance output fo the contol of the distance diection depends on the taget object, and that output vaies. Howeve, the senso output fo all taget objects has one peak, and that distance is aound 6mm, the focal length of the poximity senso element. Fo this eason, it is possible to appoach up to the focal length with no dependence on the taget object though contolling the distance diection such that the distance output peaks. Next is the contol fo positioning. The objective of this positioning contol is the movement of the cente of the palm of the hand to diectly about the taget object. As the cente 78

5 of the senso is coincident with the cente of the palm of the hand, it is acceptable to contol such that the senso position output becomes. With this convenience, the position output accuately eflects the taget position as the senso in the palm of the hand appoaches the taget object to gasp it, as shown in Fig.9, and when diectly above the taget object it can tace a smooth appoach tajectoy. B. Fingetip Contact Timing by Fingetip Poximity Senso Next, we will descibe the fingetip contact timing. In geneal, thee is the possibility of a discepancy in fingetip contact timing even when the palm of the hand is deployed above the cente of the object due to the shape of the object, etc. Fo this eason, tilting o toppling of the object occus and a safe, eliable gasp is not possible. The contact timing of each finge was made to coincide by using the poximity senso of each fingetip and deploying all the fingetips a few millimetes fom the taget object. Specifically, the fingetip position was contolled such that the distance output of the fingetip poximity senso became a maximum. Fingetip placement contol was caied out as shown by the following equation. τ = J(q)K p (p d p) J(q)K d ṗ (3) Hee J(q) is the Jacobian, pd is the taget fingetip position and p is the fingetip position. Kp and Kd ae gains. Also, the tajectoy of the fingetips was constant in the vetical diection with movement allowed in the hoizontal diection and the swing joints of the fist and thid finges fixed. C. Foce Contol fo the Gasp Next, we move to the contact phase. Fist, the object is gasped. The gasp attitude was a 2 vs 1 aangement gasp, with gasp foce contol caied out by contolling the contact foce of the 2nd finge that opposes the fixed 1st and 3d Fig. 9. Poximity Senso + Poximity Senso - Position x + + Z stage - X stage Response to the initial position eo using the poximity senso Poximity Senso - finges. Position based foce contol shown by the following equation was used fo the foce contol. τ = J(q)K p (ˆp d p) J(q)K d ṗ (4) ˆp d = p d +K fp (f d f) K fd f (5) f d is the taget contact foce, f is the contact foce. K fp and K fd ae gains. The issue when gasping a taget object is the detemination of a gasp stength suitable to the taget object. If the gasp stength is excessive, it will esult in damage to the taget object o oveloading of the engine. If it is insufficient, the taget object will be dopped. Fo this eason, the ideal gasp stength is one that does not let the object slip and fall and yet is as small as possible. On this occasion, the implementation of a gasp foce that does not allow the taget object to slip and fall was tageted though configuing the gasp foce based on slip detection. Specifically, the taget gasp foce fd was updated in the following way based on slip detemination. Slip detected ˆf d = f d +α (6) Slip not detected ˆf d = f d (7) D. Anti-Slip/Intefeence Contol fo Tanspotation Afte the gasp is completed, the obot moves into tanspotation. At this point, vaious intefeences such as inetia foce and the vibation of the highe ode joints iegulaly act on the gasped taget object. Consideations to pevent the dopping of the taget object ae made in esponse to these though appopiately inceasing the gasp foce. Because this gasp is achieved based on the foce output of the tactile senso, intefeence such as that which hindes the gasp is mateialized as a decline in CoP senso output. Meanwhile, it can be consideed that the afoementioned slippage accoding to chaacteistics of the CoP senso also mateializes as a decline in foce output. Fo this eason, it is possible to handle the vaious intefeences by means of egulating the CoP senso foce output[14]. E. Placement Using Slip Detection Finally, we have the placement opeation. It is possible to estimate a taget object elease position fom wist position, etc.; howeve, doing so esults in the isk of pessing the taget object into the floo o dopping it due to the accumulative eo of the joints and envionmental vaiations, etc. In ode to pevent this it is desiable to be able to detect the placement of the taget object and the floo. Accodingly, detemination of slippage was caied out when the wist descended, the slippage that occus due to the contact between the floo and the taget object was captued and the taget object eleased. Fig. 1. Contact timing contol by the finge s poximity senso 781 V. EXPERIMENT The pactical Pick & Place opeation was caied out with the above contols implemented[15]. The details of the expeiment wee fo the case the weight of the taget object

6 was vaied in 5-g incements fom 5g to 2g and fo the case the taget object placement position was vaied by units of 1mm within a ange of ±7mm.The gasped taget object was a cuboid made of cadboad and its weight was adjusted by packing the inside with weights. A. Expeiment Results 1) Handling Deployment Eo: Fist, we descibe the expeiment esults of the deployment eo in Fig.11. The uppe gaph shows the Z position of the wist of the hand, the middle shows the X position of the wist of the hand and the lowe shows the distance and position outputs of the poximity senso in the palm of the hand. Fom this it can be seen that the Z position of the wist of the hand is contolled such that the distance output of the net-stuctue poximity senso mounted on the palm of the hand is oughly a maximum value, that is, a distance of aound 6mm fom the object. Meanwhile, the X position of the wist of the hand is contolled such that the position output of the palm senso is almost asymptotic with, that is, to appoach diectly above the object. Also, the ange of placement eo handling is aound ±5 mm as shown in Fig.12. This is also dependent on the shape of the uppe edges of the gasped taget object but shows that the handling of a detected aea aound that of the poximity senso in the palm of the hand can be expected. 2) Contol of Contact Timing: Next, we descibe the deployment of the fingetips. The uppe gaph of Fig.13 shows the distance output of the fingetip poximity sensos and the lowe gaph shows the displacement fom the initial attitude of each fingetip. Fom this it is seen that the poximity senso output fo all of the fingetips becomes a maximum and the fingetips ae deployed at a position of a few millimetes fom the suface of the taget object. Also, in this case, it can be seen that the finges ae deployed in the ode of finge 1, finge 3, finge 2 and coincidence of contact timing is being attempted. 3) Gasping, Tanspotation and Placement: Fig.14 shows the CoP senso output egading the gasp, the 2nd finge joint toque and the wist joint position. The uppe gaph shows the foce output of the CoP senso, the middle gaph shows the diected toque value fo the 1st and 2nd Position Z (mm) Position X (mm) Senso Output (V) position (x) distance time (s) Y Position [mm] Fig. 12. Palm Poximity Senso Aea Success X Position [mm] Failue Coveing ange of the initial position eo. finge joints of the 2nd finge and the lowe gaph shows the position of the hand establishment stage in the Z and X diections. In ange I-II, the ising of the hand in the Z axis diection commences and an incease in toque in esponse to the accompanying slippage is obseved. The gasp foce that was configued to a small value in the initial state is enewed to a lage value in accodance with the ising of the hand, and its configuation to a specified value can be seen. Fig.15 is a summay of the configued gasp foces when the weight is vaied. The configued gasp foce becomes lage as the taget object weight becomes lage and the adaptive configuation of the gasp stength can be seen. In the ange II-IV, tanspotation of the gasped object is caied out. At this point, the effect of the anti-slipping/antiintefeence contol is notable, ealized in the ange i-ii. In this ange, a lage inetia foce is applied to the taget object as the tanspot diection of the hand completely changes. At this point, the finge joint toque inceases and the antiintefeence effect can be seen. The actual appeaance of the opeation is shown in Fig.16. VI. DISCUSSION 1) The position eo coection using the palm of the hand poximity senso could guide the wist position to diectly above the taget object though simple contol. As can also be seen fom Fig.16, the position elation of the hand and the taget object when appoaching the taget object makes Finge Poximity Senso Position Output (V) Finge Position (m) finge3 finge3 finge2 finge1 finge2 finge time (s) Fig. 11. Displacement of a wist joint, and the output of a poximity senso Fig. 13. Poximity senso output and fingetip displacement 782

7 CoP Senso Foce Output (V) Topue (Nm) Position Z (mm) Position X (mm) Fig Fig. 14. Gasping Foce (V) i I II III Toque 3 Toque 4 Taget Gasping Foce 15 2 time (s) ii CoP Senso Foce Output CoP senso foce output and the 2nd joint toque 5g 1g 15g 2g Object Weight (g) Relationship between object weight and ealized gasping foce guidance by the taditional technique of using a camea difficult as it is had to avoid concealing the object with finges, etc. and it can be said that the mounting of the poximity senso was exceedingly effective. Also, as the handling of the placement eo within the ange of the poximity senso of the palm of the hand can be expected, the achievement of a gasp is possible even when the pecision of the appoach fom the global ange to the taget object by camea, etc. is elatively low and so the acceleation and optimization of tasks can be attempted. Howeve, accoding to this technique, deployment of the palm diectly above the taget object may not always be possible in the case that the uppe edges of the taget object do not diectly oppose the poximity senso of the palm of the hand o fo the case the object is heteomophous. In this case, it may be possible to acquie shape infomation fo the taget object in advance by use of a camea, etc. and appopiately configue the taget value of the poximity senso in the palm of the hand. 2) The detemination opeation of the gasp attitude using the fingetip poximity sensos also geatly contibuted to the achievement of gasp. Even in a simple gasp attitude such IV as a pinching the taget object fom both sides, the contact timing of the fingetips does not coincide due to attitude eo of the taget object o initial attitude displacement when epetitive tasks ae pefomed. As a dead band exists in the tactile senso, the attitude of the taget object is alteed by the fist fingetip to contact, leading to cases whee gasping fails and so the impotance of coinciding contact timing in the achievement of gasp was seen. This fingetip tajectoy contol was simple with a fixed height diection and contol in the hoizontal diection only. Howeve, though achievement of gasp attitude and tajectoy contol based on the fingetip poximity sensos in esponse to the taget object shape, it may be possible to ealize a pecise gasp in esponse to vaious shaped objects. Futhemoe, the selection of a gasp attitude in esponse to the taget object may not be possible to detemine fom just the infomation fom the poximity senso of the palm of the hand, in which case it may be necessay to use visual infomation such as fom a camea, etc. complimentaily. 3) Dynamic gasp foce contol was achieved, ealizing a gasp foce that did not allow the object to fall while not being excessive. Even if the same object is gasped, a gasp stength configued in advance can be insufficient because vaiations in fiction conditions esult fom changes in the contact suface and diffeences in contact position in each test opeation and so an adaptive gasp stength based on slippage was extemely effective. Futhemoe, in cicumstances whee the eception of the tangential foce of the CoP senso foce output is used, sepaation of the tangential and nomal vecto foces is not possible fo the slip detection applied hee. Fo this eason, the inability to measue a pecise nomal vecto foce is an issue and the investigation of this chaacteistic o combined usage with anothe senso must be consideed. 4) As it is not necessay to assign a position to elease the taget object in advance and vaiations in placement position can be handled, a placement opeation based on slip detection may be expanded to delivey to humans o othe obots, etc. Howeve, in ode that the contact patch detection is detemined by theshold, it may be necessay to conside limiting the placement opeation ange in pactice, as the possibility exists fo the taget object to be mistakenly dopped in the case a ush intefeence is geneated. An intelligent obot as poposed above would make a gasp opeation configuation possible that is esilient to envionmental changes by means of senso integation. Also, although the poposed senso goup does not necessaily povide an abundance of high speed infomation, it showed sufficient effectiveness though its appopiate usage. VII. CONCLUSION Though integating poximity, tactile and slip senses, detection fom appoach to contact was seamlessly caied out, and an intelligent obot hand that could eliably gasp/seize was poposed. In moving towads this mateialization, an integated tactile and poximity senso was poposed by means of a punched CoP and an intelligent obot hand was 783

8 (1) Initial Position (2) Wist goes down (3) Adjustment of Position Eo (4) Completion of Position Eo Adjustment (5) Moving to Gasping Position (6) Gasping (7) Wist Rising / Gasping Foce Contol (8) Wist Moving (9) Wist goes down (1) Landing Detection (11) Releasing Object (12) Completion Pick & Place Fig. 16. Pick & Place opeation of the obot hand composed by actually mounting the senso in it. Futhemoe, Pick & Place was adopted as a pactical task using the hand, and was successful in implementation unde the conditions of 1) weight/shape/fiction conditions ae unknown and 2) placement eo exists. Although the senso goup did not necessaily povide an abundance of pecise infomation, it showed sufficient effectiveness though its appopiate usage. Heeafte, it is planned to include a poximity sense in the whole aea of the fingetips though the miniatuization of a net-stuctue poximity senso and aim fo an incease in capability of handling the gasped object by inceasing the opeational degees of feedom of the obot. REFERENCES [1] N. Fuukawa, A. Namiki, T. Senoo and M. Ishikawa, Dynamic Regasping Using a High-speed Multifingeed Hand and a High-speed Vision System, IEEE Int. Conf. on Robotics and Automation, 181/187, 26 [2] Yuji Yamakawa, Akio Namiki, Masatoshi Ishikawa, and Makoto Shimojo, One-handed Knotting of a Flexible Rope with a Highspeed Multifingeed Hand having Tactile Sensos, 27 IEEE/RSJ Intenational Confeence on Intelligent Robots and Systems/pp.73-78, 27 [3] K. Hsiao, P. Nangeoni, M. Hube, A. Saxena, A. Y Ng, Reactive Gasping Using Optical Poximity Sensos, IEEE Int. Conf. on Robotics and Automation, 298/215, 29 [4] R. Wistot, J.R. Smith, Electic Field Sevoing fo Robotic Manipulation, IEEE/RSJ Int. Conf. on Intelligent Robots and Systems, 494/499, 28 [5] H.R. Nicholls, M.H. Lee: A Suvey of Robot Tactile Sensing Technology, Int.J. Robotics Reseach, 8-3,3/3, 1989 [6] M.H. Lee, H.R. Nicholls,Tactile Sensing fo Mechatonics- A State of the At Suvey,Mechatonics, 9, 1/31, 1999 [7] T. Ishihaa, A. Namiki, M. Ishikawa, M. Shimojo, Dynamic Pen Spinning Using a High-speed Multifingeed Hand with High-speed Tactile Senso, 26 IEEE RAS Int. Conf. on Humanoid Robots, 258/263, 26 [8] Infomation and Robot Technology Resech Initiative, the Univesity of Tokyo, Announcing Technology that suppots dish washing with kitchen obots, [9] M. Ishikawa, M.Shimojo, A Method fo Measuing the Cente Position of a Two Dimensional Load Using Pessue-Conductive Rubbe, The Society of Instument and Contol Enginees, vol.18, no.7, pp , 1982 [1] S. Teshigawaa, K. Tadakuma, A. Ming, M. Ishikawa, and M. Shimojo: High Speed and High Sensitivity Slip Senso Utilizing Chaacteistics of Conducive Rubbe, Jounal of Robotics and Mechatonics, vol.21, no.2, 2-28, 29 [11] D. Gunji, Y. Mizoguchi, and M. Shimojo: Gasping Foce Contol of Multi-fingeed Robot Hand based on Slip Detection with Tactile Senso, Poc. of IEEE Int. Conf. on Robotics and Automation 28,265/261, 28 [12] S. Amamoto, M. Shimojo, Y. Shibasaki, M. Ishikawa: Object ecognition of a obot by using a poximity senso netwok system, 8th SICE System Integation Division Annual Confeince, pp , 27 [13] M. Shimojo, T. Aaki, S. Teshigawaa, A. Ming, M. Ishikawa: A Netstuctue tactile senso coveing feefom suface and ensuing highspeed esponse, IEEE/RSJ (IROS27),67/675, 27 [14] Y. Mizoguchi, S. Teshigawaa, A. Namiki, M. Ishikawa, A. Ming, M. Shimojo, Pick & Place Task Based on Slip Detection, 8th SICE System Integation Division Annual Confeince, pp , 27 [15] Y. Mizoguchi, K. Tadakuma, M.Ishikawa, A. Ming, M. SHimojo: Development of Inelligent Robot Hand - Contol of Captue and Gasp using Tactile-Poximity senso -, 9th SICE System Integation Division Annual Confeince, pp ,