23
Chapter 3 – Caterpillar Locomotion 146 3. Caterpillar Locomotion 7KLVFKDSWHUSUHVHQWVWKHUHVXOWVRIDEULHIVWXG\RIFDWHUSLOODUVDQGWKHLUORFRPRWLRQ DQGUHODWHVWKHILQGLQJRIWKLVVWXG\WRWKHVWUXFWXUDOGHVLJQDQGPRWLRQSURJUDPPLQJ RIWKHPXOWLERG\SDVVLYHOHJJHGFUDZOLQJYHKLFOH6WXOFHDQG5HLQKROW] 3.1 Introduction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’2)6WHZDUWV3ODWIRUPPHFKDQLVPVWKDWIRUPWKHPXOWLERG\ %LRORJLFDOV\VWHPVSURYLGHERWKJUHDWPRWLYDWLRQE\YLUWXHRIWKHLU VWULNLQJSHUIRUPDQFHDQGJXLGDQFHZLWKWKHGHWDLOVRIWKHLUDFWLRQV 7KH\DUHH[LVWHQFHSURRIVWKDWJLYHXVDQLQGLFDWLRQRIZKDWLVSRVVLEOH 0DUF+5DLEHUW

3. Caterpillar Locomotion - Virginia Tech

  • Upload
    others

  • View
    0

  • Download
    0

Embed Size (px)

Citation preview

Page 1: 3. Caterpillar Locomotion - Virginia Tech

Chapter 3 – Caterpillar Locomotion 146

3. Caterpillar Locomotion

7KLV�FKDSWHU�SUHVHQWV�WKH�UHVXOWV�RI�D�EULHI�VWXG\�RI�FDWHUSLOODUV�DQG�WKHLU�ORFRPRWLRQ

DQG�UHODWHV�WKH�ILQGLQJ�RI�WKLV�VWXG\�WR�WKH�VWUXFWXUDO�GHVLJQ�DQG�PRWLRQ�SURJUDPPLQJ

RI�WKH�PXOWLERG\�SDVVLYH�OHJJHG�FUDZOLQJ�YHKLFOH��6WXOFH�DQG�5HLQKROW]��������

3.1 Introduction

,Q�FRQWUDVW�WR�PRVW�PDQ�PDGH�YHKLFOHV��DQLPDOV�FDQ�JHQHUDOO\�FURVV�URXJK�WHUUDLQ�LQ

DQ�HIILFLHQW�DQG�UDSLG�IDVKLRQ��,W�ZRXOG�EH�XVHIXO�WR�KDYH�OHJJHG�PDFKLQHV�WKDW�FRXOG

LPLWDWH� WKH� H[FHOOHQW� PRELOLW\� RI� DQLPDOV�� +HQFH�� HQJLQHHULQJ� UHVHDUFKHUV� KDYH

VWXGLHG�DQLPDO�ORFRPRWLRQ�WR�JDLQ�LQVLJKWV�LQWR�WKH�GHVLJQ�RI�OHJJHG�PDFKLQHV�

)RU�WKLV�VWXG\��VHYHUDO�FDWHUSLOODU�VSHFLPHQV�ZHUH�YLGHRWDSHG�DQG�DQDO\]HG�LQ�RUGHU

WR� XQGHUVWDQG� WKHLU� SULQFLSOHV� RI� ORFRPRWLRQ�� 2EVHUYDWLRQV� LQFOXGHG� WKH� DQLPDOV

JHRPHWU\�� JDLWV�� OHJ� WUDMHFWRULHV�� DQG� ZRUNVSDFH�� 7KH� FDWHUSLOODUV� H[KLELWHG� DQ

XQH[SHFWHGO\�HIILFLHQW�JDLW�DQG�H[FHOOHQW�URXJK�WHUUDLQ�PRELOLW\�

7KHVH�REVHUYDWLRQV�FRQILUPHG�WKDW�PRVW�FDWHUSLOODU�PRWLRQ�FRXOG�EH�HPXODWHG�XVLQJ

D�OHQJWKZLVH�FKDLQ�RI���'2)�6WHZDUWV�3ODWIRUP�PHFKDQLVPV�WKDW�IRUP�WKH�PXOWLERG\

%LRORJLFDO�V\VWHPV�SURYLGH�ERWK�JUHDW�PRWLYDWLRQ�E\�YLUWXH�RI�WKHLUVWULNLQJ�SHUIRUPDQFH��DQG�JXLGDQFH�ZLWK�WKH�GHWDLOV�RI�WKHLU�DFWLRQV�

7KH\�DUH�H[LVWHQFH�SURRIV�WKDW�JLYH�XV�DQ�LQGLFDWLRQ�RI�ZKDW�LV�SRVVLEOH�

�0DUF�+��5DLEHUW�������

Page 2: 3. Caterpillar Locomotion - Virginia Tech

Chapter 3 – Caterpillar Locomotion 147

SDVVLYH�OHJJHG�FUDZOLQJ�YHKLFOH��$GGLWLRQDO�LQVLJKWV�IURP�WKH�FDWHUSLOODUV�ORFRPRWLRQ

DUH� DOVR� GLUHFWO\� DSSOLFDEOH� WR� WKH� URERWV� SK\VLFDO� VWUXFWXUH� DQG�PRWLRQ� SURJUDP�

6XFK�D�URERW�ZRXOG�SRVVHVV�VXSHUE�WHUUDLQ�DGDSWDELOLW\�

3.1.1 Previous Studies of Animal Locomotion

$� QXPEHU� RI� ELRORJLVWV� DQG� HQJLQHHUV� KDYH� LQYHVWLJDWHG� DQLPDO� ORFRPRWLRQ�

LQFOXGLQJ�:LOVRQ� ��������$OH[DQGHU� ��������0F*KHH� �������� 7RGG� �������� )LFKWHU�

HW��DO����������)LFKWHU�DQG�)LFKWHU���������'RQQHU���������DQG�PDQ\�RWKHUV�

2QH�RI�WKH�SULPDU\�UHDVRQV�WR�VWXG\�DQLPDO�ORFRPRWLRQ�LV�WR�OHDUQ�DERXW�JDLWV��$�JDLW

LV�D� WLPLQJ�VHTXHQFH� IRU� OLIWLQJ� OHJV�DQG�SODFLQJ� WKHP�RQ�WKH�JURXQG��)RU�H[DPSOH�

KRUVHV� FKRRVH� WR� HLWKHU�ZDON�� WURW�� FDQWHU�� RU� JDOORS�GHSHQGLQJ�RQ� WKHLU� GHVLUH� IRU

VSHHG��ZLOOLQJQHVV�WR�H[SHQG�HQHUJ\��DQG�WKH�WHUUDLQ�RYHU�ZKLFK�WKH\�DUH�WUDYHOLQJ�

6RQJ�DQG�:DOGURQ��������VWDWH�WKH�LPSRUWDQFH�RI�JDLW�VWXGLHV�DV�IROORZV�

���LW�KDV�EHFRPH�FOHDU�WKDW�JDLW�LV�RQH�RI�WKH�PDMRU�GHVLJQ�IDFWRUV�LQ�EXLOGLQJD� SUDFWLFDO�ZDONLQJ�PDFKLQH��*DLW� LV� WKH� GRPLQDQW� IDFWRU� LQ� WKH� GHVLJQ� RIYHKLFOH� JHRPHWU\� VLQFH� LW� UHODWHV� YHKLFOH� JHRPHWU\� WR�PRELOLW\��0RUHRYHU�WKH� JDLW� VWURQJO\� DIIHFWV� WKH� FRQWURO� DOJRULWKP���*DLW� DOVR� DIIHFWV�� WR� VRPHGHJUHH��WKH�HQHUJ\�HIILFLHQF\�RI�WKH�PDFKLQH�

7KH�IROORZLQJ�WHUPV�DUH�XVHIXO�LQ�GHVFULELQJ�DQG�FODVVLI\LQJ�JDLWV��WKH\�DUH�WDNHQ�IURP

0F*KHH��������

�)RU�DQ�Q�OHJJHG�PDFKLQH�RU�DQLPDO��LI�HYHU\�OLPE�RSHUDWHV�ZLWK�WKH�VDPH�F\FOH�WLPH�

WKHQ�WKH�JDLW�LV�VDLG�WR�EH�SHULRGLF��

$� UHJXODU� JDLW� LV� RQH� ZKHUH� DOO� RI� WKH� OHJV� SDUWLFLSDWH� HTXDOO\� LQ� SURSHOOLQJ� DQG

VXSSRUWLQJ�WKH�ERG\�

Page 3: 3. Caterpillar Locomotion - Virginia Tech

Chapter 3 – Caterpillar Locomotion 148

$�JDLW�LV�FRQVLGHUHG�V\PPHWULF�ZKHQ�WKH�PRWLRQ�RI�D�ULJKW�OHIW�SDLU�RI�OHJV��LV�H[DFWO\

KDOI�D�F\FOH�RXW�RI�SKDVH��

$�JDLW�FDQ�EH� WKRXJKW�RI�DV�D�VHULHV�RI� OLIWLQJ�DQG�SODFLQJ�HYHQWV�� ,I�QR� WZR�HYHQWV

RFFXU�VLPXOWDQHRXVO\� WKHQ�WKH�JDLW� LV�QRQ�VLQJXODU��+RZHYHU�� LI� WZR�RU�PRUH�HYHQWV

GR�RFFXU� VLPXOWDQHRXVO\�� WKHQ� WKH�JDLW� LV� VLQJXODU�� 7KHVH� WZR�GHILQLWLRQV� DUH�XVHIXO

ZKHQ� FRQVLGHULQJ� WKH� FRPELQDWRULDO� SUREOHP� RI� GHWHUPLQLQJ� WKH� WRWDO� QXPEHU� RI

WKHRUHWLFDOO\�SRVVLEOH�JDLWV�IRU�DQ�Q�OHJJHG�V\VWHP��)RU�H[DPSOH��0F*KHH��������KDV

VKRZQ�WKDW�IRU�D�TXDGUXSHG�WKHUH�DUH��������SRVVLEOH�SHULRGLF�JDLWV��LQFOXGLQJ�ERWK

VLQJXODU�DQG�QRQ�VLQJXODU�JDLWV��

0F*KHH� PHQWLRQV� WKDW� PDQ\� ��� DQG� ��OHJJHG� DQLPDOV� XVH� JDLWV� WKDW� DUH

PDWKHPDWLFDOO\�SURYHQ� WR�KDYH�RSWLPXP�VWDELOLW\��7KHVH�JDLWV�DUH�RI� WKH�ZDYH�JDLW

FODVV�

*DLW� GLDJUDPV� KDYH� EHHQ� XVHG� E\� VHYHUDO� UHVHDUFKHUV� WR� JUDSKLFDOO\� GHSLFW� JDLWV�

)LJXUH� ���� VKRZV� D� JDLW� GLDJUDP� RI� D� FRFNURDFK�� 7KH� ILOOHG� EDUV� GHQRWH� ZKHQ� D

SDUWLFXODU�OHJ�LV�LQ�LWV�VXSSRUW�SKDVH�DQG�WKH�KROORZ�EDUV�LQGLFDWH�ZKHQ�WKH�OHJ�LV�LQ

LWV� WUDQVIHU�SKDVH� �L�H�� OLIWHG�RII� WKH�JURXQG���1RWH� WKDW� WKLV�JDLW� LV�RI� WKH�ZDYH�JDLW

FODVV��VSHFLILFDOO\��LW�LV�SHULRGLF��UHJXODU��V\PPHWULF��DQG�VLQJXODU�

0RVW�SUHYLRXV�ZDONLQJ�PDFKLQH�SURMHFWV�KDYH� VRXJKW� WR� FUHDWH�ELSHG�� TXDGUXSHG�

DQG�KH[DSRG�YHKLFOHV�XVLQJ�D�VLQJOH�ULJLG�ERG\�DQG�DFWXDWHG�OHJV��7KLV�SURMHFW�DLPV

WR�FUHDWH�D�PXOWLERG\�SDVVLYH�OHJJHG�FUDZOLQJ�YHKLFOH�ZKHUH� ORFRPRWLRQ� LV�FDXVHG

SULPDULO\�E\�PRYHPHQWV�RI�WKH�ERG\�WUXQN��7KH�QDWXUDO�DQDORJXHV�XVHG�LQ�SUHYLRXV

SURMHFWV�DUH�KXPDQV��KRUVHV��DQG�DGXOW�LQVHFWV��ZKHUHDV�WKH�QDWXUDO�DQDORJXH�IRU�WKH

SURSRVHG�YHKLFOH�LV�WKH�FDWHUSLOODU�

Page 4: 3. Caterpillar Locomotion - Virginia Tech

Chapter 3 – Caterpillar Locomotion 149

Left 3

Right 3

Left 2

Right 2

Left 1

Right 1

0 1 2 3 4 5 6

Time

Leg is supporting —

Leg is not supporting —

Figure 3.1 — Gait Diagram of a Cockroach's "Tripod Gait". (Adapted from Wilson, (1966).)

3.1.2 Caterpillars

&DWHUSLOODUV�DUH�ODUYDH�RI�LQVHFWV�RI�WKH�RUGHU�OHSLGRSWHUD��ZKLFK��WKURXJK�DQ�DPD]LQJ

SURFHVV� RI� PHWDPRUSKRVLV�� EHFRPH� DGXOW� EXWWHUIOLHV� DQG� PRWKV�� 0RVW� FDWHUSLOODUV

KDYH� WZHOYH� ERG\� VHJPHQWV�� ZLWK� HLJKW� RI� WKHVH� VHJPHQWV� KDYLQJ� ODWHUDO� SDLUV� RI

Page 5: 3. Caterpillar Locomotion - Virginia Tech

Chapter 3 – Caterpillar Locomotion 150

VKRUW�OHJV���VHH�)LJV������������DQG�������&DWHUSLOODUV�KDYH�QR�ZLQJV��DQG�DUH�GHVFULEHG

E\� 'LHUO� �������� DV� KDYLQJ� �QR� KLJKO\� GHYHORSHG� VHQVH� RUJDQV��� ,QVWHDG� RI� WKH

FRPSRXQG�H\HV�IRXQG�RQ�PDQ\�LQVHFWV��WKH\�KDYH�VL[�RFHOOL��ZKLFK�DUH��EDUHO\�DEOH

WR�GLVWLQJXLVK�OLJKW�IURP�GDUN���RQ�HDFK�VLGH�RI�WKHLU�KHDGV�

$OO�FDWHUSLOODUV�FDQ�PDNH�VLONHQ�WKUHDGV�LQ�YDU\LQJ�DPRXQWV��'LHUO���������7KHLU�WKUHDG

LV�H[WUXGHG�IURP�D�VSLQQHUHW�ORFDWHG�MXVW�EHORZ�WKHLU�PRXWKV��0DQ\�FDWHUSLOODUV�FDQ

XVH� WKHLU� VLON� WKUHDGV� DV� EULGJHV� IURP� RQH� WUHH� EUDQFK� WR� DQRWKHU� DQG� WR� ORZHU

WKHPVHOYHV�WR�WKH�JURXQG�

Figure 3.2 — Side View of a Standing Tent Caterpillar

Figure 3.3 — Side View of a Pitching Tent Caterpillar

Page 6: 3. Caterpillar Locomotion - Virginia Tech

Chapter 3 – Caterpillar Locomotion 151

Figure 3.4 — Bottom View of Turning (Yawing) Tent Caterpillar

7KH�ERG\��RU�WUXQN��RI�FDWHUSLOODUV�LV�VRIW�DQG�IOH[LEOH��6SHFLDO�PXVFOHV�OLQLQJ�WKH�ERG\

ZDOO�H[HUW�SUHVVXUH�RQ�WKH�ERG\�IOXLGV��$V�D�UHVXOW��WKH�ERG\�LV�NHSW�WXUJLG��HIIHFWLYHO\

FUHDWLQJ�D��K\GURVWDWLF�VNHOHWRQ���&KDSPDQ��������

&DWHUSLOODUV�KDYH�WZR�GLIIHUHQW�NLQGV�RI�OHJV��7KH�IRUZDUG�VL[�OHJV���WKH�WKRUDFLF�OHJV��

HDFK�KDYH�D�VLQJOH�OHJ�VHJPHQW�DQG�D�FODZ��'LHUO���������7KH�UHDU�OHJV�DUH�UHIHUUHG�WR

DV�SUROHJV��7KH�SUROHJV�DUH�IOHVK\�F\OLQGULFDO�SURWXEHUDQFHV�IURP�WKH�ERG\�ZDOO�DQG

KDYH�QR�VHJPHQWV���RU�OLQNV���$W�WKH�HQG�RI�HDFK�SUROHJ�LV�D�FLUFOH�RI�FXUYHG�KRRNV�RU

§FURFKHWV¨�ZKLFK�DUH�XVHG�IRU�JULSSLQJ�WKH�WHUUDLQ��$FFRUGLQJ�WR�UHVHDUFK�GHVFULEHG

LQ�&KDSPDQ���������HDFK�SUROHJ�KDV�UHWUDFWRU�PXVFOHV�ZKLFK�DUH�XVHG�IRU�VKRUWHQLQJ

WKH� SUROHJ� ZKHQ� LW� PRYHV� GXULQJ� ORFRPRWLRQ�� IRU� HQJDJLQJ� DQG� GLVHQJDJLQJ� WKH

FURFKHWV��DQG�IRU�FUHDWLQJ�D�YDFXXP�VR�WKDW�WKH�SUROHJ�ZLOO� IXQFWLRQ�DV�D�VXFNHU�RQ

VPRRWK�VXUIDFHV�

&DWHUSLOODUV�PRYH�YLD�D�ZDYH�RI�PXVFXODU�FRQWUDFWLRQV�WKDW�VWDUW�DW�WKH�SRVWHULRU�DQG

SURJUHVV�IRUZDUG�WR�WKH�DQWHULRU��'XULQJ�WKLV�PRWLRQ��DW� OHDVW�WKUHH�VHJPHQWV�DUH�LQ

YDU\LQJ�VWDWHV�RI�FRQWUDFWLRQ�DW�WKH�VDPH�WLPH��7KH�WZR�IHHW�RQ�HLWKHU�VLGH�RI�HDFK

ERG\�VHJPHQW�PRYH�WRJHWKHU��DV�D�XQLW��,W�LV�EHOLHYHG�WKDW�WKH�PXVFOH�FRRUGLQDWLRQ�LV

Page 7: 3. Caterpillar Locomotion - Virginia Tech

Chapter 3 – Caterpillar Locomotion 152

FRQWUROOHG� SULPDULO\� E\� D� FHQWUDO� QHUYRXV� SURFHVV� PRGLILHG� E\� ORFDO� UHIOH[HV

�&KDSPDQ��������

7KH� EDFN� WR� IURQW� §ZDYH¨� RI� PRWLRQ� PHQWLRQHG� DERYH� LV� FRPPRQ� WR� DOPRVW� DOO

DQLPDOV� ZLWK� DSSHQGDJHV� �:LOVRQ�� ������� +RZHYHU�� WKH� LQ�SKDVH� PRWLRQ� RI� WKH

ODWHUDO� OHJ�SDLUV� LV� YHU\�XQXVXDO�� EHFDXVH�ZLWK�PRVW�RWKHU� DQLPDOV�� WKH� WZR� OHJV�RI

HDFK�ODWHUDO�SDLU�PRYH�H[DFWO\�D�KDOI�F\FOH�RXW�RI�SKDVH�IURP�HDFK�RWKHU��0F*KHH�

������

7KH� FDWHUSLOODU� LV� HVSHFLDOO\� LQWHUHVWLQJ� EHFDXVH� RI� LWV� DELOLW\� WR� HDVLO\� RYHUFRPH

REVWDFOHV�WKDW�DUH�ODUJH�UHODWLYH�WR�LWV�VL]H��GHVSLWH�KDYLQJ�YHU\�OLPLWHG�VHQVH�RUJDQV

�'LHUO��������

3.2 Experimental Program

6HYHUDO�FDWHUSLOODUV�ZHUH�FDSWXUHG�IURP�WKH�ZHE��RU�§WHQW¨��ZKLFK�WKH\�KDG�PDGH�LQ�D

FKHUU\�WUHH��%\�FRPSDULQJ�WKH�VSHFLPHQV�ZLWK�WKH�GHVFULSWLRQ�LQ�6WHKU���������LW�ZDV

GHWHUPLQHG�WKDW�WKH\�ZHUH�HDVWHUQ�WHQW�FDWHUSLOODUV���0DODFRVRPD�DPHULFDQXP���7KLV

VSHFLHV�LV�FRQVLGHUHG�WR�EH�D�SHVW�EHFDXVH�WKH\�GHIROLDWH�PDQ\�IUXLW�WUHHV�

3.2.1 Videotaping Caterpillar Locomotion

7KH� VSHFLPHQV� ZHUH� YLGHRWDSHG� LQGLYLGXDOO\� XVLQJ� D� 6XSHU�9+6� FDPHUD� DQG

UHFRUGHU��%HFDXVH�RI�WKH�FDWHUSLOODUV�VPDOO�VL]H�� WKH�YLGHR�FDPHUD� OHQV�ZDV�XVHG�LQ

WKH�PDFUR�PRGH��7KH�QRUPDO�ODERUDWRU\�OLJKWLQJ���D�FRPELQDWLRQ�RI�IOXRUHVFHQW�DQG

QDWXUDO� OLJKW���ZDV�XVHG�� ,W�ZDV�IHDUHG�WKDW�XVLQJ�EULJKW�VSRWOLJKWV�PLJKW�FKDQJH�WKH

DQLPDOV� EHKDYLRU�� RU� WKDW� KHDW� IURP� WKH� OLJKWV� PLJKW� KDUP� WKHP�� %HFDXVH� RI� WKH

PRGHUDWH� OLJKWLQJ� FRQGLWLRQV�� WKH� FDPHUDV� GHSWK� RI� ILHOG� ZDV� OLPLWHG� WR

DSSUR[LPDWHO\���FP�

Page 8: 3. Caterpillar Locomotion - Virginia Tech

Chapter 3 – Caterpillar Locomotion 153

1XPHURXV� SUREOHPV� UHVXOWHG� IURP� WKH� VSHFLPHQV� LQGHSHQGHQW� VWDWH� RI� PLQG�� 7R

TXRWH� WKH� +DUYDUG� /DZ�� §8QGHU� WKH� PRVW� ULJRURXVO\� FRQWUROOHG� FRQGLWLRQV� RI

SUHVVXUH��WHPSHUDWXUH��YROXPH��KXPLGLW\�DQG�RWKHU�YDULDEOHV��WKH�RUJDQLVP�ZLOO�GR�DV

LW�GDPQ�ZHOO�SOHDVHV�¨��%ORFK��������� ,Q�WKH�FDVH�RI�WKLV�H[SHULPHQW�� WKH�VSHFLPHQV

XVXDOO\� FUDZOHG� DLPOHVVO\� DURXQG� WKH� WDEOH�� WULHG� WR� FUDZO� RQWR� WKH� FDPHUD� OHQV�

DWWHPSWHG� WR� HVFDSH�� RU� UHIXVHG� WR� PRYH� DW� DOO�� $V� D� UHVXOW�� WKH� DQLPDOV� ZRXOG

ZDQGHU�LQ�DQG�RXW�RI�IRFXV��RU�RXW�RI�YLHZ�DOWRJHWKHU�

7KLV�SUREOHP�ZDV�DOOHYLDWHG�E\�XVLQJ�D�UROOHG�XS�VKHHW�RI�SDSHU�WR�FUHDWH�D�SDWKZD\

VLPLODU� WR� WKH� WUHH� EUDQFKHV� RI� WKH� FDWHUSLOODUV� QDWXUDO� KDELWDW�� 7KH� FDWHUSLOODUV

LQVWLQFWLYHO\�FUDZOHG�DORQJ�WKH�HGJH�RI�WKH�SDSHU��DOORZLQJ�WKH�H[SHULPHQWHU�WR�KROG

WKH�SDSHU�UROO�VR�WKDW�WKH�FDWHUSLOODU�UHPDLQHG�LQ�IRFXV��$OVR��DV�WKH�DQLPDO�FUDZOHG

IURP�RQH�HQG�RI�WKH�SDSHU�WR�WKH�RWKHU��WKH�H[SHULPHQWHU�FRXOG�WUDQVODWH�WKH�SDSHU

LQ� WKH� RSSRVLWH� GLUHFWLRQ� VR� DV� WR� SUHYHQW� WKH� FDWHUSLOODU� IURP�ZDONLQJ� RXW� RI� WKH

VWDWLRQDU\�FDPHUDV�ILHOG�RI�YLHZ��0LOOLPHWHU�JUDSK�SDSHU�ZDV�XVHG��DOORZLQJ�YDULRXV

OHQJWK�PHDVXUHPHQWV�WR�EH�PDGH�RI�WKH�DQLPDOV�ERGLHV�DQG�ORFRPRWLRQ�ZKHQ�WKH

YLGHRWDSH�ZDV�UHSOD\HG�ODWHU�LQ�VORZ�PRWLRQ�

,Q� DGGLWLRQ� WR� REVHUYDWLRQV� PHQWLRQHG� DERYH�� WZR� VWHHS� �KLOOV�� ZHUH� FRQVWUXFWHG

IURP�IROGHG�SDSHU�VR�WKDW�WKH�FDWHUSLOODUV�REVWDFOH�FURVVLQJ�JDLWV�FRXOG�EH�REVHUYHG�

7KH�VSHFLPHQV�ZHUH�DOVR�SODFHG�RQ�SODWH�JODVV�DQG�LQ�JODVV�EHDNHUV��DQG�ILOPHG�IURP

XQGHUQHDWK��VR�DV�WR�JHW�D�ERWWRP�YLHZ�RI�WKHLU�ORFRPRWLRQ�

5HFRUGLQJ�WKH�YLGHRWDSH�UHTXLUHG�DSSUR[LPDWHO\����KRXUV�WR�SURGXFH�WKH�UHVXOWLQJ

URXJKO\���KRXUV�RI�WDSH��$IWHU�WKH�WDSH�ZDV�ILQLVKHG��LW�ZDV�UHYLHZHG�VHYHUDO�WLPHV�

FULWLFDO� VHTXHQFHV� FRXOG� EH� SOD\HG� LQ� VORZ� PRWLRQ� DQG� IUDPH�E\�IUDPH� WR� DOORZ

FDUHIXO�REVHUYDWLRQ��+RZHYHU��WKH�VORZ�WLPH�UHVROXWLRQ�RI�WKH�FDPHUD������LQWHUODFHG

IUDPHV� SHU� VHFRQG��� FDXVHG� VLJQLILFDQW� EOXUULQJ� WR� WKH� LPDJHV�� SDUWLFXODUO\� RI� WKH

DQLPDOV�IHHW�DV�WKH\�PRYHG�

Page 9: 3. Caterpillar Locomotion - Virginia Tech

Chapter 3 – Caterpillar Locomotion 154

3.2.2 Determination of Workspace

0HDVXULQJ� WKH�FDWHUSLOODUV�ZRUNVSDFH�ZDV�RQH�RI� WKH�PRVW� LPSRUWDQW�REVHUYDWLRQV

RI�WKLV�VWXG\��EHFDXVH�ZRUNVSDFH�LV�WKH�GHFLGLQJ�IDFWRU�WKDW�LQGLFDWHV�ZKHWKHU�D�PDQ�

PDGH� URERW� FDQ� GXSOLFDWH� WKH� PRWLRQ� RI� WKH� FDWHUSLOODU�� ,GHDOO\�� GHWHUPLQLQJ� WKH

ZRUNVSDFH�RI�D�GHYLFH� LV�D� VLPSOH�PDWWHU�RI�PRYLQJ� LW� WR� WKH� OLPLWV�RI� LWV� UDQJH�RI

PRWLRQ� DQG� WKHQ� PHDVXULQJ� LWV� DQJOHV� DQG� OHQJWKV�� +RZHYHU�� PHDVXULQJ� WKH

ZRUNVSDFH�RI� DQ\� LQYHUWHEUDWH� DQLPDO� LV� FRPSOLFDWHG� E\� WKH� IDFW� WKDW� WKHLU� ERGLHV

EHKDYH�LQ�DQ�HODVWRPHULF�IDVKLRQ�� ,Q�WKH�FDVH�RI�FDWHUSLOODUV�� WKH\�DUH�VPDOO�HQRXJK

WKDW�WKH\�FDQ�HDVLO\�EH�VTXDVKHG�RU�WRUQ�DSDUW�E\�D�UHVHDUFKHU�DWWHPSWLQJ�WR�PRYH

WKHP�WR�WKHLU�PRWLRQ�UDQJH�OLPLWV�

%\�QXGJLQJ� WKH�FDWHUSLOODU�ZLWK� WKH� ILQJHUV��RU�HLWKHU�PRYLQJ�RU�EHQGLQJ� WKH�SDSHU

WKH�FDWHUSLOODU�ZDV�JULSSLQJ��LW�ZDV�SRVVLEOH�WR�PDQHXYHU�WKH�FDWHUSLOODUV�ERG\�LQWR�D

QXPEHU�RI�GLIIHUHQW�SRVLWLRQV��,W�ZDV�SUHVXPHG�WKDW�WKH�FDWHUSLOODU�ZRXOG�WXUQ�ORRVH

RI� WKH� SDSHU�ZKHQ� LW� EHFDPH� XQFRPIRUWDEOH�ZLWK� D� SDUWLFXODU� ERG\� SRVLWLRQ�� 7KH

PRVW�H[WUHPH�SRVLWLRQ�DW�ZKLFK�WKH�FDWHUSLOODU�WXUQHG�ORRVH�ZDV�FRQVLGHUHG�WR�EH�LWV

OLPLW�IRU�WKDW�SDUWLFXODU�W\SH�RI�PRWLRQ��7KLV�LV�DQ�DVVXPSWLRQ�WKDW�WKH�ERG\�SRVLWLRQV

ZKLFK�DUH�WROHUDEOH�WR�WKH�DQLPDO�FDQ�DOVR�EH�UHDFKHG�YLD�WKH�DQLPDOV�RZQ�PXVFXODU

FRQWURO���L�H��LQ�LWV�ZRUNVSDFH��

$IWHU� UHFRUGLQJ�� WKH� YLGHRWDSH� ZDV� UHYLHZHG� WR� ILQG� WKH� VHTXHQFH� ZKHUH� WKH

VSHFLPHQ� H[KLELWHG� LWV� PRVW� H[WUHPH�PRYHPHQW�� 7KH� WDSH� ZDV� SDXVHG� LQ� IUHH]H�

IUDPH�PRGH�DW�WKH�FDWHUSLOODUV�PRVW�FRQWRUWHG�PRPHQW��DQG�LWV� OHQJWK�DQG�DQJXODU

PHDVXUHPHQWV�ZHUH�HVWLPDWHG��7\SLFDOO\��VHYHUDO�RI�WKH�FDWHUSLOODUV�VHJPHQWV�ZRXOG

EH�GRLQJ�WKH�VDPH�W\SH�RI�PRWLRQ��VR�WKDW�WKH�JURVV�PRWLRQ�RI�D�JURXS�RI�VHJPHQWV

FRXOG�EH�PHDVXUHG��WKLV�UHVXOW�ZDV�WKHQ�GLYLGHG�E\�WKH�QXPEHU�RI�VHJPHQWV� LQ�WKH

JURXS� WR� \LHOG� D� SHU� VHJPHQW� YDOXH�� 'HWHUPLQDWLRQ� RI� UROO� DQJOHV� ZDV� KHOSHG� E\

PHDVXULQJ�RII�RI� WKH� ORQJLWXGLQDO� VWULSH�GRZQ� WKH�FDWHUSLOODUV�EDFN�� 6LPLODUO\�� SLWFK

Page 10: 3. Caterpillar Locomotion - Virginia Tech

Chapter 3 – Caterpillar Locomotion 155

DQG� \DZ� DQJOHV� ZHUH� JDXJHG� IURP� WKH� FLUFXPIHUHQWLDO� JURRYHV� ORFDWHG� DW� WKH

VHJPHQW�LQWHUVHFWLRQV�

3.3 Experimental Results

7KH� FDWHUSLOODUV� H[KLELWHG� LPSUHVVLYH� ORFRPRWLRQ� FDSDELOLWLHV�� ,Q� JHQHUDO�� WKHLU

ORFRPRWLRQ�ZDV�VWDWLFDOO\�VWDEOH��XQOLNH�PDPPDOV���7KH�RQO\�H[FHSWLRQV�ZHUH�ZKHQ

WKH\�FUDZOHG�XS�VRPH�YHUWLFDO�VXUIDFHV�XVLQJ�WKHLU�WLQ\�FURFKHWV��DQG�VRPHWLPHV�ORVW

WKHLU�JULS�DQG� IHOO��$IWHU� WKH� IDOOV�� WKH\�XVHG�D� VWDWLFDOO\�XQVWDEOH�PRYH� WR� UROO� EDFN

RYHU�LQWR�D�VWDQGLQJ�SRVLWLRQ��'XULQJ�WKH�WDSLQJ�WKH\�GHPRQVWUDWHG�VXSHULRU�PRELOLW\

HYHQ�ZKHQ�WKH\�ZHUH�QRW�XVLQJ�WKHLU�VLON�RU�FODZV�

3.3.1 Caterpillar Geometry and Workspace

7DEOH� ���� OLVWV�PHDVXUHPHQWV� WDNHQ� IURP� WKUHH� QHDUO\� LGHQWLFDO� WHQW� FDWHUSLOODUV�� ,Q

JHQHUDO�� WKH� OHQJWK�PHDVXUHPHQWV� KDYH� DQ�XQFHUWDLQW\�RI� DERXW� ��PP��1RWH� WKDW�

EHFDXVH� RI� WKH� JHQHUDOO\� XQFRRSHUDWLYH� QDWXUH� RI� WKH� VSHFLPHQV�� UHSHWLWLYH� WHVWV

ZHUH�QRW�PDGH�IRU�VHYHUDO�RI�WKH�PHDVXUHPHQWV�

3.3.2 Caterpillar Gaits

$V�GLVFXVVHG�LQ�WKH�OLWHUDWXUH��FDWHUSLOODUV�PRYH�E\�D�ZDYH�RI�PXVFXODU�FRQWUDFWLRQV

WKDW�SURFHHG�IURP�WKH�UHDU�RI�WKH�DQLPDO�WR�LWV�IURQW��'XULQJ�HDFK�ORFRPRWLRQ�F\FOH�

WKLV��ZDYH��LV�FOHDUO\�YLVLEOH�DV�LW�WUDYHOV�XS�WKH�FDWHUSLOODUV�ERG\�

Page 11: 3. Caterpillar Locomotion - Virginia Tech

Chapter 3 – Caterpillar Locomotion 156

Table 3.1 — Approximate Physical and Locomotion Characteristics of Eastern TentCaterpillars

Note 1: This may not have been voluntary. Also note that this is pitching up; negative pitch was not

measured but is believed to be much smaller.

Note 2: After the experiments, when the caterpillars were released, they appeared to move much

faster than this 'maximum'. Unfortunately, this was not documented on video and so their

true top speed is unknown. The caterpillars' decision to finally demonstrate their speed

capabilities may be attributable to their pleasure at finally being released from the jar, or

more likely, the pavement was hot.

1XPEHU�RI�ERG\�VHJPHQWV ��

1XPEHU�RI�OHJV ��������SDLUV�

0DVV ������JUDPV

6WDQGLQJ�OHQJWK ���PP� �/

0LQLPXP�OHQJWK ���PP� �����/

0D[LPXP�OHQJWK ���PP� �����/

5DWLR�RI�PLQLPXP�WR�PD[LPXP�OHQJWK ����

%RG\�GLDPHWHU ����PP

0D[LPXP�SLWFK�SHU�VHJPHQW ��o������6HH�1RWH���EHORZ��

0D[LPXP�\DZ�SHU�VHJPHQW ��o

0D[LPXP�UROO�SHU�VHJPHQW ��o

/DWHUDO�OHJ�SDLU�VSDFLQJ ��PP���EXW�FDQ�YDU\�LQ�RUGHU�WR�JULS�

0D[LPXP�REVHUYHG�VSHHG �����PP�VHF�XVLQJ������ZDYHV�6HH�1RWH���EHORZ��

$YH��OHQJWKZLVH�VSDFLQJ�RI�DGMDFHQW�SUROHJV ����PP

7\SLFDO�SUROHJ�VWHS�OHQJWK ����PP

Page 12: 3. Caterpillar Locomotion - Virginia Tech

Chapter 3 – Caterpillar Locomotion 157

8QIRUWXQDWHO\��ZKHQHYHU�WKH���WKRUDFLF�OHJV�PRYHG��WKH\�DSSHDUHG�EOXUU\�ZKHQ�WKH

YLGHRWDSH�ZDV� UHSOD\HG��7KXV�� LW�ZDV�QRW�SRVVLEOH� WR�FRQILUP�ZKHWKHU� WKH� WKRUDFLF

OHJV� PRYHG� LQ� WKH� H[DFW� VDPH�PDQQHU� DV� WKH� SUROHJV�� 2IWHQ�� LW� VHHPHG� WKDW� WKH

FDWHUSLOODUV� PLJKW� EH� XVLQJ� WKHLU� WKRUDFLF� OHJV� DV� IHHOHUV� WR� SHUFHLYH� WKH� WHUUDLQ�

)RUWXQDWHO\�� WKH� YLGHR� LPDJHV� RI� WKH� SUROHJV� ZHUH� FOHDU� HQRXJK� WR� GUDZ� VRPH

FRQFOXVLRQV��7KHUHIRUH��WKH�JDLW�VWXG\�FRQFHQWUDWHG�RQ�WKH�FDWHUSLOODUV�SUROHJV��$OVR�

VLQFH�WKH�SUROHJV�KDYH�QR�VHJPHQWV��'LHUO���������WKH\�DUH�VLPLODU�WR�WKH�OHJV�RQ�WKH

SURSRVHG�URERW�

8QOLNH� DGXOW� LQVHFWV� DQG� PRVW� DQLPDOV�� WKH� FDWHUSLOODUVª� SUROHJV� DOZD\V� PRYH

WRJHWKHU��L�H��LQ�SKDVH�

%HIRUH� WDSLQJ�� WKH� DXWKRU� H[SHFWHG� D� VLQJOH� SDLU� RI� OHJV� WR� EH� LQ�PRWLRQ� IRU� HDFK

�ZDYH��� VSHFLILFDOO\�� WKDW� MXVW� DV� OHJ� SDLU� i� ILQLVKHG� LWV� VZLQJ� DQG� UHWXUQHG� WR� WKH

JURXQG�� WKH� QH[W� OHJ� SDLU�� i �1�� ZRXOG� OLIW� RII� RI� WKH� JURXQG�� +RZHYHU�� WKH

REVHUYDWLRQV�VKRZ�WKDW�FDWHUSLOODUV�UDUHO\�HYHU�XVH�WKLV�§VLQJOH�OHJ�SDLU�SHU�ZDYH¨�JDLW�

,QVWHDG��WKH\�XVH�D�PXFK�PRUH�HIILFLHQW�§GRXEOH�OHJ�SDLU�SHU�ZDYH¨�JDLW��DV�LOOXVWUDWHG

LQ�)LJ������

7KH� WRS� SLFWXUH� RI� )LJ�� ���� VKRZV� WKH� FDWHUSLOODU� VWDQGLQJ� LQ� LWV� QHXWUDO� VWDQFH� DQ

LQVWDQW� EHIRUH� LW� EHJLQV� WR� PRYH� WKH� SUROHJV� RQ� VHJPHQW� ���� �WKH� DQDO� FODVSHUV��

%HWZHHQ�T = 0� DQG�T = 3�� VHJPHQWV��������� DQG���� VHTXHQWLDOO\�PRYH� IRUZDUG�E\

PHDQV� RI� D� ZDYH� RI� PXVFXODU� FRQWUDFWLRQV�� $W� T = 3� ZH� VHH� WKDW� VHJPHQW� ��� LV

FRPSUHVVHG�DQG�WKH�OHJV�RI�VHJPHQW���KDYH�WLOWHG�IRUZDUG��$W�T = 4 ��VHJPHQW���KDV

OLIWHG� LWV� WZR� OHJV� RII� WKH� JURXQG� DQG� LV� DW� WKH� PLGGOH� RI� LWV� VZLQJ� IRUZDUG�

6LPXOWDQHRXVO\�� VHJPHQW� �� KDV� EHJXQ� WR� FRQWUDFW� DQG� WLOW� LWV� OHJV� IRUZDUG� LQ

SUHSDUDWLRQ� IRU� OLIWLQJ�� $W� T = 5�� VHJPHQW� �� LV� VKRZQ� MXVW� EHIRUH� LW� WRXFKHV� GRZQ�

0HDQZKLOH��VHJPHQW���KDV�OLIWHG�LWV�OHJV�DQG�LV�QRZ�QHDU�WKH�SHDN�RI�LWV�VZLQJ��DQG

VHJPHQW���LV�VWDUWLQJ�WR�FRQWUDFW�DQG�WLOW� LWV� OHJV�IRUZDUG��$Q�LQVWDQW�DIWHU�T = 5�� WKH

OHJV�RI�VHJPHQW���WRXFK�GRZQ�DQG��VLPXOWDQHRXVO\��WKH�OHJV�RI�VHJPHQW���OLIW�RII�WKH

Page 13: 3. Caterpillar Locomotion - Virginia Tech

Chapter 3 – Caterpillar Locomotion 158

JURXQG�� 7KH�SLFWXUH� IRU� T = 6� LV� MXVW� OLNH� T = 5�� H[FHSW� WKDW� WKH� �ZDYH�� KDV�PRYHG

IRUZDUG�DQRWKHU�VHJPHQW�VR�WKDW�LW�LV�QRZ�FHQWHUHG�RYHU�VHJPHQW����$IWHU�T = 6��WKH

UHPDLQLQJ� SUROHJV� PRYH� LQ� D� VLPLODU� IDVKLRQ�� DQG� WKH� ZDYH� FRQWLQXHV� WR� PRYH

IRUZDUG�DORQJ�WKH�FDWHUSLOODUV�ERG\�XQWLO�VHJPHQW���FRPSOHWHV�LWV�PRYH�

7KXV��WKH�JHQHUDO�SDWWHUQ�LV�DV�IROORZV��MXVW�DV�OHJ�SDLU� i WRXFKHV�GRZQ��OHJ�SDLU� i � 2

WDNHV�RII���,W�DSSHDUHG�WKDW�HDFK�VHJPHQW�EHJDQ�PRYLQJ�ZKHQ�WKH�SUHYLRXV�VHJPHQW

ZDV�KDOI�ILQLVKHG�ZLWK�LWV�VWHS��7KH�SUROHJ�SRUWLRQ�RI�WKLV�JDLW�LV�JUDSKLFDOO\�GHSLFWHG

LQ�)LJ������

Figure 3.5 — Locomotion Sequence of a Tent Caterpillar

(Note that the segment numbering scheme used here is different than that used inentomology literature.)

Page 14: 3. Caterpillar Locomotion - Virginia Tech

Chapter 3 – Caterpillar Locomotion 159

Figure 3.6 — Tent Caterpillar Gait Diagram

$SSO\LQJ� WKH� WHUPLQRORJ\� JLYHQ� LQ�0F*KHHV� ZRUN� WR� WKLV� DQLPDO� UHVXOWV� LQ� VRPH

GLIILFXOWLHV��VLQFH�WKH�GHILQLWLRQV�ZHUH�DSSDUHQWO\�QRW�PDGH�ZLWK�FDWHUSLOODUV�LQ�PLQG�

6WULFW� DGKHUHQFH� WR� WKH�GHILQLWLRQV�ZRXOG�FDXVH�XQQHFHVVDU\�FRQIXVLRQ�E\� ODEHOLQJ

WKH� FDWHUSLOODUV� ULJKW�OHIW� OHJ� SDLU� PRWLRQV� DV� �QRQ�V\PPHWULF�� EHFDXVH� WKHLU

PRYHPHQWV� DUH� H[DFWO\� LQ�SKDVH� UDWKHU� WKDQ� RXW� RI� SKDVH�� 7KXV�� LW� LV� GHVLUDEOH� WR

UHILQH�WKH�GHILQLWLRQV�VOLJKWO\�E\�VWDWLQJ�WKDW�ODWHUDO�OHJV�WKDW�PRYH����o�RXW�RI�SKDVH

DUH� H[KLELWLQJ� �RSSRVLWH� SKDVH� V\PPHWU\��� DQG� ODWHUDO� OHJV� WKDW�PRYH� WRJHWKHU� DUH

GHPRQVWUDWLQJ��LQ�SKDVH�V\PPHWU\���5HODWLYH�SKDVH�DQJOHV�RWKHU�WKDQ��o�DQG����

o

DUH� WHUPHG� �QRQ�V\PPHWULF��� �$Q�H[DPSOH�RI�D� WUXH�QRQ�V\PPHWULF�JDLW� LV�D�KRUVHV

Page 15: 3. Caterpillar Locomotion - Virginia Tech

Chapter 3 – Caterpillar Locomotion 160

JDOORS��� )LJXUHV� ���� DQG� ���� FOHDUO\� FRQWUDVW� WKH� FRFNURDFKV� RSSRVLWH�SKDVH

V\PPHWU\�ZLWK�WKH�FDWHUSLOODUV�LQ�SKDVH�V\PPHWU\�

8VLQJ� WKLV� VOLJKWO\� PRGLILHG� YHUVLRQ� RI� WKH� FODVVLILFDWLRQ� WHUPLQRORJ\� JLYHQ� LQ� WKH

UHIHUHQFH� E\� 0F*KHH� �������� LW� FDQ� EH� VDLG� WKDW� WKH� FDWHUSLOODUV� DFKLHYHG

ORFRPRWLRQ�E\�XVLQJ�SHULRGLF��VLQJXODU��UHJXODU��LQ�SKDVH�V\PPHWULF��ZDYH�JDLWV�

&DWHUSLOODUV�FDQ�FRQWLQXRXVO\�YDU\�WKH�IUHTXHQF\�RI�WKHLU� ORFRPRWLRQ�F\FOH� LQ�RUGHU

WR� DFKLHYH� GLIIHUHQW� VSHHGV��'XULQJ� KLJKHU� VSHHG�PRWLRQ�� VHYHUDO� VSHFLPHQV�ZHUH

REVHUYHG� ZLWK� URXJKO\� ���� VHSDUDWH� �ZDYHV�� RI� IRRW� PRWLRQ� WUDYHOOLQJ� DORQJ� WKHLU

WUXQNV� VLPXOWDQHRXVO\�� � ,Q� RQH� LQVWDQFH�� ZKHQ� D� FDWHUSLOODU� ZDV� SXVKHG� IURP� WKH

IURQW�� LW� EDFNHG�XS�XVLQJ�D� UHYHUVHG�JDLW� LQ�ZKLFK� WKH�ZDYH�RI� FRQWUDFWLRQV� VLPSO\

WUDYHOHG�IURP�WKH�IURQW�RI�LWV�ERG\�WR�WKH�UHDU�

3.3.2.1 Rough Terrain

:KHQ� VWDQGLQJ� RQ� RU� FURVVLQJ� RYHU� XQHYHQ� WHUUDLQ�� WKH� FDWHUSLOODUV� ERG\� SRVWXUH

FRQIRUPHG�WR�WKH�WHUUDLQ�LQ�D�VPRRWKHG�PDQQHU��7KDW�LV��LW�GLG�QRW�FRQIRUP�WR�HYHU\

VPDOO�LUUHJXODULW\��EXW�LW�GLG�DVVXPH�WKH�JHQHUDO�VKDSH�RI�WKH�WHUUDLQ��1R�DWWHPSW�ZDV

PDGH�WR�NHHS�WKH�OHJV�DOLJQHG�LQ�D�YHUWLFDO�GLUHFWLRQ��LQVWHDG��DV�WKH�FDWHUSLOODUV�ERG\

DGDSWHG�WR�WKH�XQGHUO\LQJ�WHUUDLQ��LWV�OHJV�ZHUH�NHSW�SHUSHQGLFXODU�WR�WKH�FHQWHUOLQH

RI�WKH�FDWHUSLOODUV�ERG\�WUXQN��7KLV�UHVXOWHG�LQ�HDFK�OHJ�EHLQJ�QRUPDO�WR�D�VPRRWKHG

DSSUR[LPDWLRQ�RI�WKH�ORFDO�JURXQG�VXUIDFH�RQ�ZKLFK�LWV�IRRW�UHVWHG��:KHQ�VWDQGLQJ

RQ�URXJK� WHUUDLQ�� WKH�FDWHUSLOODU�JHQHUDOO\�PDLQWDLQHG� LWV� ORQJLWXGLQDO� OHJ�VSDFLQJ�DW

URXJKO\�HTXDO�DUF�OHQJWKV�DORQJ�LWV�FXUYLQJ�ERG\�

7KH�FDWHUSLOODUV�FURVVHG�PRVW�KLOOV�DQG�WUHQFKHV�XVLQJ�WKH�WHUUDLQ�FRQIRUPLQJ�PDQQHU

GHVFULEHG�DERYH��,QGHHG��KLOO�W\SH�REVWDFOHV�EDUHO\�VORZHG�WKH�FDWHUSLOODUV�GRZQ��7KH

YLGHR�VWLOO� LQ� )LJ������ VKRZV�D�FDWHUSLOODU� FOLPELQJ�D� WDOO�REVWDFOH� UHODWLYH� WR� LWV�RZQ

VL]H�� FRQVLVWLQJ� RI� WKH� DXWKRUªV� LQGH[� DQG� PLGGOH� ILQJHUV�� 0RPHQWV� ODWHU� WKH

FDWHUSLOODU�KDG�PRYHG�LWV�FHQWHU�RI�PDVV�WR�WKH�WRS�RI�WKH�§KLOO¨�

Page 16: 3. Caterpillar Locomotion - Virginia Tech

Chapter 3 – Caterpillar Locomotion 161

Figure 3.7 — Eastern Tent Caterpillar Climbing a Large “Hill”

3.3.2.2 Crossing Large Obstacles

6LQFH�FDWHUSLOODUV�KDYH����OHJV��WKH\�FDQ�UHPDLQ�VWDWLFDOO\�VWDEOH�ZLWKRXW�KDYLQJ�DOO�RI

WKHLU� IHHW� RQ� WKH� JURXQG�� 7KH� FDWHUSLOODUV� XVH� WKLV� WR� JRRG� DGYDQWDJH� ZKHQ� WKH\

HQFRXQWHU� ODUJH� WHUUDLQ� IHDWXUHV�ZLWK� DEUXSW� FKDQJHV� LQ� FXUYDWXUH�� 7KH� FDWHUSLOODUV

XVHG�D�FDQWLOHYHU�PDQHXYHU�VLPLODU�WR�WKDW�VKRZQ�LQ�)LJ������WR��EULGJH��DFURVV�DEUXSW

JDSV� LQ� WKH� WHUUDLQ�� ,QWHUHVWLQJO\�� RQFH� D� FDWHUSLOODU� KDG� EULGJHG� D� JDS� DQG� IRXQG

IRRWKROGV�IRU�LWV�IURQW�OHJV��LW�UHVXPHG�WKH�VDPH�JDLW�DV�EHIRUH��7KDW�LV��WKH�JDLW�ZDV

VWLOO� D� SHULRGLF�� LQ�SKDVH� V\PPHWULF�� VLQJXODU� ZDYH� JDLW�� $OWKRXJK� WKH� VHJPHQWV

Page 17: 3. Caterpillar Locomotion - Virginia Tech

Chapter 3 – Caterpillar Locomotion 162

GLUHFWO\�RYHU�WKH�YRLG�ZHUH�RXW�RI�FRQWDFW�ZLWK�WKH�JURXQG��WKH\�QHYHUWKHOHVV�PRYHG

IRUZDUG�DW� WKH�DSSURSULDWH� WLPH�GXULQJ�HDFK� ORFRPRWLRQ�F\FOH�� 7R� WKH�REVHUYHU�� LW

DSSHDUHG� WKDW� WKH�FDWHUSLOODU�ZDV� �SXPSLQJ�� LWV�PDVV� IURP�RQH�EDVH�RI� VXSSRUW� WR

DQRWKHU�

3.3.2.3 Recovering After a Fall

2FFDVLRQDOO\��ZKHQ�D�FDWHUSLOODU�ZDV�FOLPELQJ�XS�D�YHUWLFDO�SDSHU�VXUIDFH�� LW� ORVW� LWV

JULS�DQG�IHOO��HQGLQJ�XS�RQ�LWV�EDFN��$IWHU�ERXQFLQJ�RQ�LPSDFW��WKH�FDWHUSLOODU�ZRXOG

UROO�RYHU��ULJKW�LWVHOI��DQG�WKHQ�EH�RQ�LWV�ZD\�DJDLQ�

,QWHUHVWLQJO\�� WKH� ULJKWLQJ� PDQHXYHU� ZDV� QRW� VWDWLFDOO\� VWDEOH�� 6SHFLILFDOO\�� LI� D

FDWHUSLOODU�ILQGV�LWVHOI�O\LQJ�RQ�LWV�EDFN��LW�UDLVHV�VHYHUDO�VHJPHQWV�IURP�ERWK�WKH�IURQW

DQG� UHDU� RI� LWV� ERG\� XSZDUG� DQG� VOLJKWO\� WR� RQH� VLGH�� 7KLV� HIIHFWLYHO\� PRYHV� WKH

FDWHUSLOODUV�FHQWHU�RI�JUDYLW\�EH\RQG�WKH�VXSSRUW�EDVH�RI�LWV�URXQGHG�EDFN��6LQFH�WKLV

LV� DQ�XQVWDEOH�SRVLWLRQ�� JUDYLW\� FDXVHV� WKH�XSUDLVHG�ERG\� VHJPHQWV� WR� IDOO�� FDXVLQJ

WKH�ERG\�WR�UROO�RII�RI�LWV�EDFN�RQWR�LWV�VLGH��2QFH�RQ�LWV�VLGH��WKH�FDWHUSLOODU�UROOV���o

RQWR� LWV� IHHW� DJDLQ�� 7KLV� UROO�PDQHXYHU� EHJLQV� DW� VHJPHQWV� �� DQG� ���� 7KH� URWDWLQJ

DFWLRQ�SURFHHGV�IURP�WKH�WZR�HQGV�WRZDUGV�WKH�FHQWHU�RI�WKH�FDWHUSLOODU�XQWLO�DOO�RI

WKH�VHJPHQWV�KDYH�UROOHG�EDFN�RQWR�WKHLU�IHHW��+HQFH��WKH�LQVWDELOLW\�WXUQV�RXW�WR�EH

EHQHILFLDO�LQ�WKLV�FDVH�

3.3.3 Leg Pair Trajectories

1RWLFH� LQ� 7DEOH� ���� WKDW� WKH� FDWHUSLOODUV� DYHUDJH� OHQJWKZLVH� VSDFLQJ� EHWZHHQ

DGMDFHQW�SUROHJV�LV�����PP��,I�RQO\�RQH�VHJPHQW�PRYHG�DW�D�WLPH��ZH�ZRXOG�H[SHFW

HDFK�VHJPHQWV�VWULGH�WR�EH���RU���PP�ORQJ�EHFDXVH�WKH�VHJPHQWV�KDYH�DQ�DYHUDJH

PLQLPXP�WR�PD[LPXP�OHQJWK�UDWLR�RI�������+RZHYHU��7DEOH�����DOVR�OLVWV�WKH�W\SLFDO

SUROHJ�VWHS�OHQJWK�WR�EH�����PP��DFWXDOO\�EH\RQG�WKH�LQLWLDO�SRVLWLRQ�RI�WKH�QH[W�OHJ

SDLU�

Page 18: 3. Caterpillar Locomotion - Virginia Tech

Chapter 3 – Caterpillar Locomotion 163

7KLV�H[WUD�ODUJH�VWULGH�LV�EURXJKW�DERXW��SDUWLDOO\��E\�WKH�GRXEOH�OHJ�SDLU�SHU�ZDYH�JDLW�

,W�DOVR�UHVXOWV�IURP�WKH�FDWHUSLOODUV�XVH�RI�OHJ�WUDMHFWRULHV�WKDW�LQFRUSRUDWH�SLWFKLQJ�RU

WLOWLQJ�RI�WKH�OHJ�SDLUV�WR�HIIHFWLYHO\�VZLQJ�WKH�OHJV��1RWLFH�LQ�)LJ������WKDW�MXVW�EHIRUH

D�VHJPHQWV�OHJV�OLIW�RII�RI�WKH�JURXQG��WKH�VHJPHQW�EHJLQV�WR�WLOW�IRUZDUG��'XULQJ�LWV

VZLQJ�SKDVH��WKH�OHJ�SDLU�VWUDLJKWHQV�WR�D�YHUWLFDO�RULHQWDWLRQ��7KHQ��DW�WKH�HQG�RI�LWV

VWURNH�� WKH� OHJ�SDLU� WLOWV�EDFNZDUG�DV� LW� UHWXUQV� WR� WKH�JURXQG��7KLV�SLWFKLQJ�PRWLRQ

DOORZV�ORQJHU��PRUH�HIILFLHQW�VWHSV��DOORZLQJ�HDFK�VHJPHQW�PRUH�WLPH�WR�DFFHOHUDWH

DQG�GHFHOHUDWH��7KXV��D�JLYHQ�VSHHG�FDQ�EH�SURGXFHG�XVLQJ�ZHDNHU�PXVFOHV�

7KH� SUROHJ� UHWUDFWLRQ� GXULQJ� ORFRPRWLRQ� PHQWLRQHG� LQ� WKH� &KDSPDQ� ������

UHIHUHQFH�FRXOG�QRW�EH�FRQILUPHG�LQ�WKLV�VWXG\�EHFDXVH�WKH�YLGHR�LPDJHV�RI�WKH�OHJV

ZHUH�EOXUUHG��+RZHYHU��LI�WKH�SUROHJV�ZHUH�UHWUDFWLQJ�GXULQJ�ORFRPRWLRQ��WKH\�ZHUH

QRW� UHWUDFWLQJ� YHU\� IDU�� ,W� ZDV� FOHDU� WKDW� ZKHQ� D� VHJPHQW� ZDV� DW� WKH� SHDN� RI� LWV

PRWLRQ�� LW� ZDV� DSSUR[LPDWHO\� ��PP� DERYH� WKH� UHVW� RI� WKH� FDWHUSLOODU� �QRWLFH� KRZ

VHJPHQW� �� §KXPSV¨� DW� T = 4� LQ� )LJ�� ������ ,W� PD\� EH� WKDW� WKLV� YHUWLFDO� GLVWDQFH� LV

VXIILFLHQW�IRU�WKH�SUROHJV�WR�VZLQJ�ZLWKRXW�UHWUDFWLQJ�

3.4 Application to Robot Design

6LQFH� WKH� FDWHUSLOODUV� ORFRPRWLRQ� UHVXOWV�PDLQO\� IURP� ERG\�WUXQN�PRYHPHQWV�� DQG

EHFDXVH�LWV�XQMRLQWHG�SUROHJV�DUH�HVVHQWLDOO\�SDVVLYH��WKH�FDWHUSLOODU�LV�DQ�DSSURSULDWH

ELRORJLFDO� DQDORJ� RI� WKH� PXOWLERG\� SDVVLYH�OHJJHG� FUDZOLQJ� YHKLFOH�� $V� VXFK�� LW

SURYLGHV�H[FHOOHQW�H[DPSOHV�RI�WKH�SRWHQWLDO�RI�VXFK�D�YHKLFOH��DQG�JLYHV�LQVLJKWV�LQWR

WKH�GHVLJQ�DQG�PRWLRQ�SURJUDPPLQJ�RI�LWV�PHFKDQLFDO�FRXQWHUSDUW�

Page 19: 3. Caterpillar Locomotion - Virginia Tech

Chapter 3 – Caterpillar Locomotion 164

3.4.1 Legs

)URP�WKH�REVHUYDWLRQV�RI� WKH�FDWHUSLOODUV�SUROHJ�VHJPHQWV�� LW� LV�FRQFOXGHG� WKDW� WKH

SURSRVHG�YHKLFOH�FDQ�HPXODWH�PRVW�RI� WKH�FDWHUSLOODUV�PRELOLW\�ZLWKRXW� WKH�XVH�RI

DFWXDWHG� OHJV�� ,W� DSSHDUV� WKDW� VLPSOH� OHJV� ULJLGO\� DWWDFKHG� WR� WKH� SD\ORDG� ER[HV

ZRXOG�EH�HIIHFWLYH��KRZHYHU��WKLV�GRHV�QRW�UXOH�RXW�WKH�SRVVLELOLW\�RI�DGGLQJ�SDVVLYH

�QRQ�DFWXDWHG�� IUHHGRPV� WR� WKH� OHJV� WR� HQKDQFH� WHUUDLQ� DGDSWDELOLW\�� VKRFN

DEVRUSWLRQ��DQG�RU�HQHUJ\�VWRUDJH�

3.4.2 Actuation Units

'XULQJ� WKH� HDUO\� VWDJHV� RI� WKH� FUDZOLQJ� YHKLFOH� FRQFHSWXDO� GHVLJQ�� WKH� GRXEOH

RFWDKHGUDO� 9*7� ZDV� FRQVLGHUHG� DV� D� SRVVLEOH� FDQGLGDWH� IRU� XVH� LQ� WKH� DFWXDWLRQ

XQLWV� �VHH� )LJ�� ������+RZHYHU�� DIWHU� WKH� FDWHUSLOODU� REVHUYDWLRQV�� LW� EHFDPH�REYLRXV

WKDW� WKH� GRXEOH� RFWDKHGUDO� 9*7� VLPSO\� GLG� QRW� KDYH� WKH� QHFHVVDU\� PRELOLW\� WR

HPXODWH� WKH�FDWHUSLOODUV� ORFRPRWLRQ�� ,Q�SDUWLFXODU�� LW� ODFNHG� WKH�QHFHVVDU\� WRUVLRQDO

PRELOLW\�DERXW�LWV�ORQJLWXGLQDO�D[LV�DQG�LW�ZDV�FRPSOHWHO\�LQDGHTXDWH�IRU�WKH�WDVN�RI

KDYLQJ�WZR�DFWXDWLRQ�XQLWV�FRRSHUDWLYHO\�FRQWURO�WKH�SRVLWLRQ�RI�WKHLU�FRQQHFWLQJ�OHJ

SDLU�

7HVWV� SHUIRUPHG� XVLQJ� D� FRPSXWHU� PRGHO� GHYHORSHG� E\� WKH� DXWKRU� DQG� D� VFDOH

SK\VLFDO�PRGHO� FRQVWUXFWHG� E\� 3DXO�0HOH� ������� LQGLFDWH� WKDW� D� 6WHZDUW� 3ODWIRUP

PHFKDQLVP�FDQ�EH�PDGH�ZLWK�D�ZRUNVSDFH�YHU\�VLPLODU�WR�WKDW�RI�RQH�ERG\�VHJPHQW

RI� D� FDWHUSLOODU�� 7KHUHIRUH�� LW� FDQ� EH� FRQFOXGHG� WKDW� LW� LV� NLQHPDWLFDOO\� IHDVLEOH� WR

HPXODWH�WKH�FDWHUSLOODUV�H[FHOOHQW�PRELOLW\�XVLQJ�WKH�SURSRVHG�GHVLJQ�

3.4.3 Linear Actuators

$V�VKRZQ�LQ�7DEOH������WKH�UDWLR�RI�WKH�FDWHUSLOODUV�PLQLPXP�WR�PD[LPXP�OHQJWK�LV

������7KLV�LV�HQFRXUDJLQJ�EHFDXVH�VLPSOH����VHFWLRQ�WHOHVFRSLQJ�OLQHDU�DFWXDWRUV�FDQ

Page 20: 3. Caterpillar Locomotion - Virginia Tech

Chapter 3 – Caterpillar Locomotion 165

DOVR� KDYH� WKLV� UDQJH� RI�PRWLRQ�� 7KXV�� WKH� 6WHZDUW� 3ODWIRUPV� FDQ� XVH� VLPSOH� OLQHDU

DFWXDWRUV� UDWKHU� WKDQ�KDYLQJ� WR�XVH�PRUH�FRPSOLFDWHG�FRPSRXQG� OLQHDU� DFWXDWRUV�

�VHH�)LJ�������

approx. 0.65 s

s

Simple Linear Actuator

Compound Linear Actuator

Figure 3.8 — Comparison of Compound Linear Actuator and Simple Linear Actuator

3.4.4 Motion Programming

%HFDXVH� WKH� DFWXDWLRQ� XQLWV� FDQ� KDYH� ZRUNVSDFHV� VLPLODU� WR� D� FDWHUSLOODU� ERG\

VHJPHQW��LW�LV�SRVVLEOH�WR�SURJUDP�D�FUDZOLQJ�YHKLFOH�WR�LPLWDWH�WKH�JDLWV�DQG�OHJ�SDLU

WUDMHFWRULHV�WKDW�WKH�FDWHUSLOODUV�ZHUH�REVHUYHG�WR�XVH�

,W�ZDV�VXUSULVLQJ�WKDW�WKH�FDWHUSLOODUV�GRXEOH�OHJ�SDLU�SHU�ZDYH�JDLW�DQG�WKHLU�WLOWLQJ�OHJ

SDLU� WUDMHFWRULHV� ZHUH� XVHG� LQ� DOO� VLWXDWLRQV�� LQFOXGLQJ� REVWDFOH� FURVVLQJ�� 7KH

FDWHUSLOODUV�KDG�ORQJHU��VPRRWKHU�VWULGHV�WKDQ�H[SHFWHG��6R�WKH�TXHVWLRQ�DULVHV��§:LOO

SURJUDPPLQJ�D�PXOWLERG\�SDVVLYH�OHJJHG�FUDZOLQJ�YHKLFOH�WR�LPLWDWH�WKH�FDWHUSLOODUV

Page 21: 3. Caterpillar Locomotion - Virginia Tech

Chapter 3 – Caterpillar Locomotion 166

©PRWLRQ� SURJUDPª� DFWXDOO\� EH� EHQHILFLDO"¨� $QVZHULQJ� WKLV� TXHVWLRQ� ZLOO� EH� DQ

LPSRUWDQW�WHVW�FDVH�IRU�WKH�VLPXODWLRQ�WRROV��,Q�IDFW��WKH�VLPXODWLRQ�ZLOO�EH�H[SUHVVO\

GHVLJQHG�ZLWK�WKLV�TXHVWLRQ�LQ�PLQG�

3.4.5 Payload Boxes

)URP�WKH�GLVFXVVLRQ� LQ�6HFWLRQ���������RQ�UHFRYHULQJ�DIWHU�D� IDOO�� LW� LV�DSSDUHQW� WKDW

WKH� FDWHUSLOODUV� F\OLQGULFDO� ERG\� LV� YHU\� XVHIXO�� 7R� HQDEOH� WKH� SURSRVHG� URERW� WR

SHUIRUP�WKLV�PDQHXYHU��LW�LV�QHFHVVDU\�WR�FKDQJH�WKH�FRQFHSWXDO�GHVLJQ��6SHFLILFDOO\�

WKH� SD\ORDG� ER[HV� VKRXOG� EH� FKDQJHG� WR� EH� URXQGHG� RQ� WRS�� �VHH� )LJ�� ������ $

F\OLQGULFDO�VKDSH�ZRXOG�DOVR�EH�PRUH�HIILFLHQW�IURP�WKH�SRLQW�RI�YLHZ�RI�YROXPH�SHU

VXUIDFH�DUHD�DQG�SD\ORDG�YROXPH�SHU�YHKLFOH�PDVV�

Figure 3.9 — Rounded Top Payload Boxes

)LJXUH������VKRZV�D�FRPSXWHU�UHQGHULQJ�WKDW�LOOXVWUDWHV�D�FRPSOHWH�FUDZOLQJ�YHKLFOH

ZLWK�WKLV�FKDQJH�LPSOHPHQWHG�

Page 22: 3. Caterpillar Locomotion - Virginia Tech

Chapter 3 – Caterpillar Locomotion 167

Figure 3.10 — A Crawling Vehicle Using Payload Boxes with Rounded Tops

3.5 Chapter Summary

7KH� FDWHUSLOODU� REVHUYDWLRQV� UHSRUWHG� LQ� WKLV� FKDSWHU� LQFOXGH� PHDVXUHPHQWV� RI� LWV

JHRPHWU\�� UDQJH�RI�PRWLRQ�� JDLWV�� DQG� OHJ� WUDMHFWRULHV�� 7KHVH� REVHUYDWLRQV� FRQILUP

WKDW� WKH� FDWHUSLOODU� LV� LQGHHG� D� VXLWDEOH� ELRORJLFDO� FRXQWHUSDUW� IRU� WKH� PXOWLERG\

SDVVLYH�OHJJHG�FUDZOLQJ�YHKLFOH��7KH�FDWHUSLOODU�REVHUYDWLRQV�KDYH�KDG�D�GLUHFW�HIIHFW

RQ� WKH� GHVLJQ� RI� WKH� DFWXDWRUV�� DFWXDWLRQ� XQLWV�� OHJV�� SD\ORDG� ER[HV�� DQG� PRWLRQ

SURJUDP�RI�WKH�YHKLFOH�

Page 23: 3. Caterpillar Locomotion - Virginia Tech

Chapter 3 – Caterpillar Locomotion 168

0RVW� QRWDEO\�� WKH� FDWHUSLOODUV� JDLW� LV� VXUSULVLQJO\� HIILFLHQW� DQG� YHUVDWLOH�� WKH� VDPH

EDVLF� JDLW� LV� XVHG� IRU� DOPRVW� DOO� ORFRPRWLRQ�� LQFOXGLQJ�REVWDFOH� FURVVLQJ�� 6LQFH� WKH

SUHOLPLQDU\�PHFKDQLFDO� GHVLJQ� RI� WKH� FUDZOLQJ� YHKLFOH� KDV� EHHQ� VKRZQ� WR� KDYH� D

UDQJH�RI�PRWLRQ�VLPLODU�WR�WKDW�RI�WKH�FDWHUSLOODUV��LW�LV�NLQHPDWLFDOO\�IHDVLEOH�WR�LPLWDWH

WKH�FDWHUSLOODU�JDLWV�DQG�OHJ�VWHS�WUDMHFWRULHV�ZLWK�WKH�FUDZOLQJ�YHKLFOH��7KLV�LGHD�ZLOO

EH� SXUVXHG� DQG� WHVWHG� LQ� VXEVHTXHQW� FKDSWHUV� DV� ZH� GHYHORS� WKH� PRWLRQ

SURJUDPPLQJ� DOJRULWKPV� DQG� FRPSXWHU� VLPXODWLRQ� WHFKQLTXHV� WKDW�ZLOO� EH� XVHG� DV

WRROV� LQ� WKH� FRQILJXUDWLRQ� GHVLJQ� VWDJH� RI� WKH� PXOWLERG\� SDVVLYH�OHJJHG� FUDZOLQJ

YHKLFOH��%XW�ILUVW�ZH�PXVW�OD\�WKH�JURXQGZRUN�LQ�WKH�QH[W�FKDSWHU�¦�0RGHOLQJ�