Article信州大学工学部紀要 63: 19-28 (1988)departmental bulletin pape

FUWA,  Yasushi

KITAHARA,  Hidehiko

MORIMOTO,  Naohisa

NAKAMURA,  Yatsuka

English

Shinshu University Institutional Repository

        Journal of the Faculty of Engineering, Shinshu Univeysity, No.63, 1988 19                          ･twy･Itti<esreqgesreg ag63ng         A Self-Supporting Quadruped Walking-Robot        Yatsuka NAKAMURA*, Yasushi FUMA**, Hidehiko KITAHARA***                       and Naohisa MORIMOTO***                         (Received October 31, 1987)     A robot has been constructed which is capable of walking with four legs with neither external controller nor external power supply. The gait of the robot is a simulation of the gait of a real pony, data of which were collected from a videotape of a walking pony. A mechanism which may provide a light weight structure with high strength, is applied to all9joints on the body. Most of the ICs in the hardware are C-MOS ver- sions effective for the reduction in electric consumption. Servo pulse motors to be con- trolled by CPUs are adopted on this robot to reduce the weight and increase the con- trollability of the robot.                            I. Introduction    Recently, many processes of production are being automated by computersin factories. A great advance has been macle in the speed and accuracy of theaction of robots. Some robots which have recently been developedi-3) can walkstably. Most robots cannot move for themse}ves without outer controilers orpower supply, because they need not only heavy servo motors containing servopacks but also a large quantity of electric current2･4,5). We have been studyingmotors for the intelligent robot, and have recently developed some robots (e.g., a micro cat, i. e., a quadruped waiking robot). We have developed a self-supporting quadruped walking-robot capable of walking without cables connectedwith external controllers and power supply. The features of thls robot are asfoilows:1. The rnechanism of each joint is improved so that light structure may be  provided with high strength.2. Most ICs in the hardware are composed of C-MOS versions in order to reduce  electric consumption.3. Drivers of motors are light because they employ 8-bit processors.  * Professor, Department of Information Engineering. ** Assistant, Department of Information Engineering. *** Student of master course.**** Student.2e Yatsuka NAKAMvRA, Yasushi FuwA, et al.   In this paper, the outline of the mechanism and control method is describedin sections 2 and 3, respectively.                            2. Mechanism   The self-supporting quadruped walking-robot is rnodeled after a real pony.The joints and degrees of freedom of this robot are shown in Fig. I, wheresymbols "A" to "I" refer to the joints and those "1" to "10" to the motor. Therobot has nine joints, the number of degrees of freedom of joints "F" and "H"is two, and that of the other joints is one. Joints "A" to "H" consist of areduction gear and a motor system. Joint "I" has no motor, serving to absorbthe straln of the robot.   Figure 2 shows the structure of the joints, Fig. 2-a) the structure of thelegs, and Fig. 2-b) the structure of the front shoulders. The joints of each legmust support the dead ioad of the robot. Therefore, the joints have to be lockedwhile the motors are out of action; the set of a worm wheel and a worm gear,which is used for the reduction of gear ratio and has the character of self-lock,is hard to rotate under external forces. For reducing the weight of the transportsystem of each joint, we use timing-belts and pulleys. The reduction ratio ofmotorsl to8 is 30 to l, and that of motors9 and 10 is 12 to 1.   The motor system was improved in thatthe interactive DC motor we haddeve!eped before6) was provided. The motor system is featured by its highreliability in high speed rotation, and is capable of keeping correct positioning.le-nt 7Ccml･ 4  10 1,D I2BA3Cg86EF' 8H 7G'""t"'  65crn   l,.l.Fig. 1 Overview: the joints and the degrees of freedom.                 A Self-Supporting Quadruped Wa!king-Robot 21The driver circuit of each rnotor comprizes an 8-blt CPU, which secures highreliability in the state of overload. Figure 3 shows the range of degrees offreedom for each joint. The range of movement of motors 1, 3, 5, and 7 ls fromOO to 960 and that of motors 2, 4, 6, and 8 is from -480 to 480. Tkese joints                         Pulley                               timing belt                                 ･x                                          MOtOrg,lo <- Front ieg                                       Front view             Front side                                 '                   a) b)   Fig. 2 Structure of the joints: a) shows one of the legs: b) shows the shoulder.                                                f                                      -lso                                       ,,!li:::le                                        ttt.                                        15o                                             .,..-v 1 s o                                      r-48                          -48e                                +4g'6+48'"O li '･･      Oe.  i' "'kx. + 4 8 ,i' +9 6, '･･ e ":'      '     oe    Fig. 3s'" l"';･. eo i . -" 4 8 e, g g-u････-"'   +96o              OOoRange of movement of+4g;ttttt:   't-t  ': +96e the jomts.,, o  +15o  "''-48e      OeeOe22 Yatsul<a NAI<AMuRA, Yasushi FuwA, et al.have absolute encoders. The range of niovement of motors 9 and 10 is from-l50 to lso.   This robot is made of aluminum board, welghing about 70 kg. The controlunit (comprizing CPU, I/O, I/F, and Driver) and power regulator are installedin the body of robot, and the batteries are attached on its back.                      3. Comtrol of the Robot3.1 Control methed   It seems that there are two klnds of control methods of robots, one ofwhich is static and the other is dynamlc. The dynamic control has been studiedby many researchers.7) Practically, these methods of robot control utilize feedbackcontrol. When these methods are handled by a CPU, decrease in processjngspeed (for reading the informat!on from the sensor and controlling the motor)will raise a serious problem. For our robot, the control method adopted isdynamic, working in such a way that usual wa!k is executed by a hardware-1 fi"B 2 wh 3 (fi1 4 wh5 cFi} 6 wh 7 cF" 8 on9 fFi) IZ       11ft      12(`iil') im1317      14imlff"A ls      15imfFit lg      16imCFn 2zonwh21 fi) 22 {1) 23 gFA 24 fuFig. 4 Examlpe data obtained from pictures of a      videotape recording a real pony                 A Self-Supporting Quadruped Walking-Robot 23logic independent of the CPU, the hardware-logic produces pulses from writtendata in ROMs for each motor, and tkat the CPU reads information from thesensor and encoder and keeps checking the state of the robot.   The initial conditions of the robot aRd its handling (turning to the left orright) are controlled directly by a CPU, and the CPU processed handling forwalking is centrolled by hardware-logic.   Each motor is controlled by a CPU or hardware-logic, and the contrel methodusing hardware-log!c is as follows. The hardware-iogic reads a data written inROMs by a clock different from the CPU ciock, and each motor is rotated bytkis data. The frequency of this reading clock can be changed, and it is possibieto control the walking speed of the robot by changing this frequency. The CPUgives the hardware-loglc the initial address of ROMs and controls the hardware-loglc.   Data in ROMs are produced from videotape pictures which have been takenwith a walking pony. First, we get data on the correlation of every joints witha computer (data shown in Flg. 4). Next, the data were changed in form from   ROMI   DirectionD7,D6,･･,D2,Di,DO     ROM2      PulseD7,D6,･･,D2;D1,Deo1?3tt.    ROMD7,D6,･･,OIOI03011101ClglgOllOlll11011111Ol#1010111010191o123.'.3D2,Dl,DO10101010ICIIIIII11180110101110111010101018111111ol23.311OOOOooogooo113OO09ooGoeoo111C090ooeoeoeooooooROMI & ROM2D7 : Motor 8D6 : Motor 7D5 : Motor 6D4 : Motor S         Fig. 5 An                    ROM3                    D7 :D3 : Motor 4                    D6 :D2 : Motor 3                    D5 :Dl : Motor 2                    D4 :DC : Motor 1                    DO : example of a pattern of data ofMotor 9<Pulse)Motorle(Pulse)Motor 9(Direction)MotorlO(Direction)Endflag of dataROMs.24 Yatsuka NAKAMURA, YasushiControl    BoxIN IP/UTFFuwA,    EetNal.CODERSRem addressbus'un'iMemoryx4,NY"""'                        N               moto rl                   :               motorlO            Fig. 6 Overview: a block diagram of the hardware-logic.graphic lnformation to data of the degrees of joint, and further to a row ofdirection angles and also to a sequence of pulses. In Fig. 5, a format of ROMsare shown. Direction data of motors 1 to 8 are stored in ROMI, and pulse dataln ROM2. Data D4 to D7 are for motors 9 and 10, and data DO in ROM3 indicatesan end of moving cycle.3.2 Contrel hardware   The structure of the control hardware is shown in Fig. 6. The hardwareconslsts of blocks such as 10 drivers for the motor, an input-interface, anoutput-interface, and a control-box. The control hardware uses no servo packsfor the reduction of weight of robot. Most of the ICs in this logic are C-MOSverslons for the decrease in electrlc consumption, and absolute encoders areinstalled on the working polnts of rnotors 1 to 8. In OUTPUT 1, three ROMsand a hardware-logic to read ROM are arranged, by which the read addressand read clock are formed. OUTPUT 2 chooses data from OUTPUT 1 or theCPU and sends them to the driver circuits. It changes the data format for theNtx'.OUTPUTl-.-･"-･i HardwareLogic'l･ill-I-/"F."iNfiiLj･1-,AddreceROM1dataAddre"sROM2dataAddtteeROM3dtstaE･IbNII-""'"'I"i'E''''"-'''"'II..,OUTPUT2EA--DriversA SelftSupporting Quadruped Walking･Robot 25Read clockAddress clockROM addressROM dataLATCHIData seiDirectionPulse datawLrLrLrym, rLrym,=F==i===F=ii               '    ･ "'Maf ' , l ewFig. 7 Timing diagram of the hardware-logic.drivers of the motor and sends data to the driver circuits. I/F is an inputinterface, which has 10 input ports to read data of each encoder, controllingdata, and addresses to read ROM.   Timing diagrams for reading data from ROMs, changing data, etc. areshown in Fig. 7. The binary counter in OUTPUT l produces a ROM address,and the lnitial address is set by the CPU. The clock to count up addresses iscontrol!ed by a CPU or by a fiip-fiop changed by blt 1 (==DO) in ROM 3.   The direction data read from ROM is latched by LATCHI, and puiseETtM71----･--"------...---ETtOi{TiOPSHMIPSMM2 --------t--------PSMMIOESCtFMCORPMHANSR-------"----ANSnFMCeRCOR PSMnoMManualsgPSMMAINROMpaANSRESCFig. 8 A blocl< diagram of the control software.26 Yatsuka NAKAMvRA, Yasushi FuwA, et al.data are sent to the drlver while a Data SeHine is low. The data which arepointed by the ROM address are read simultaneously from ROMs 1 and 2. Themotor rotates one step (1.80) during the rising phase of the wave form producedfrom the pulse data.   Three 12V batteries are used for operation, one being used for the controlunit and the others for the motors. The 5V voltage for the control unit isproduced by the switching regulator from 12V voltage; the service duration ofthe battery was about 20 minutes in eur system.3.3 Software to control the rebot    The software is written by the PSM method8) so that concurrent process-ing may be effected. Figure 8 shows the block diagram8) of this software,which is composed oH2 PSMs, PSM-MAIN, PSM-Ml, ･････-, PSM-MIO, and PSM-ROM. All the PSMs move concurrently; PSM-MAIN serves to control the wholerobot, PSM-Mn (n==1 to 10) serve to control each motor directly, and PSM-ROM serves to control the hardware-logic for reading data in the ROM.                           4. Conelusions    This robot can walk as fast as about two meters per minute. It canreproduce continual walks without conducting any calculation for maintainingequilibrium. Parallel processlngs of hardware and software have enabled the robotto walk smoothly and at high speed. We are plannlng to prolong the durationand increase the speed of walk.                         5. AckRowledgment    We would like to express our gratitude to TAKANO Co., Ltd. for thecooperation in making the frame and mechanical parts, and to Mr. HASIMTwaakyondo for reading the manuscrlpt.                             References1) R. B. Mchee, D. E. Orin, D. R. Pugh, and M. R, Patterson, A hierarchically structured system for computer control of a hexapod walking rnachine, Theory Pract. Rob. Manip., pp. 375-381 (1985).2) H. Miura, I. Shimoyama, M. Mitsuishi, and H. Kimura, Dynamical walk of quadruped robot (collie-1), Rob. Res., pp. 317-324 (1985).3) A. Takanishi, M. Ishida, Y. Yamazaki, and I. Kato, The realization of dynamic walking by the biped walking robot WL-10RD, Proc. 85 Int. Con£ Adv. Rob., pp. 459- 466 (1985).4) K. Okamoto, A. Ooka, Y. Wada, Y. Kida, and K. Yoshida, Development of Four-iegged Vehicle for an Intelligent Robot, JRSJ, Vol. 3, No. 4, pp. 277--284 (!985) (in Japanese).5) S. Hirose, Y. Fukuda, and H. Kikuchi, The Gait Control System of the Quadruped6)7)8)                 A Self-Supporting Quadruped Walking-Robot 27Walking Vehicle, JRSJ, Vol. 3, No. 4, pp. 304--324 (1985) (in Japanese).  O. Azami, Y. Nakamura, and Y. Fuwa, The interactive DC motor of which magneticfield is controlled by CPU directly, IECE (1985) (in Japanese). S. Hanabusa, Computrol No. 9, CORONA PUBLISKING CO., LTD., pp. 90-106 (1985)(in Japanese). Y. Nakamura and ¥. Fuwa, A Simple Programming Method of State Transition Diagramsfor Parallel Processings, J, of Information Processing, Vol. 5, No. 3, pp. 148-154 (l982).

A Self-Supporting Quadruped Walking-Robot

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A Self-Supporting Quadruped Walking-Robot

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