A well developed technology of coordination of multi-limbed locomotory systems is now available. Results from a NASA sponsored study of several years ago are presented. This was a simulation study of a three-limbed locomotion/manipulation system. Each limb had six degrees of freedom and could be used either as a locomotory grasping hand-holds, or as a manipulator. The focus of the study was kinematic coordination algorithms. The presentation will also include very recent results from the Adaptive Suspension Vehicle Project. The Adaptive Suspension Vehicle (ASV) is a legged locomotion system designed for terrestrial use which is capable of operating in completely unstructured terrain in either a teleoperated or operator-on-board mode. Future development may include autonomous operation. The ASV features a very advanced coordination and control system which could readily be adapted to operation in space. An inertial package with a vertical gyro, and rate gyros and accelerometers on three orthogonal axes provides body position information at high bandwidth. This is compared to the operator's commands, injected via a joystick to provide a commanded force system on the vehicle's body. This system is, in turn, decomposed by a coordination algorithm into force commands to those legs which are in contact with the ground

Klein, C. A.

Waldron, K. J.

English

NASA Technical Reports Server

Multi-Limbed Locomotion Systems for Space Construction 
and Maintenance 
KJ. Waldror~ and C.A. glda 
Ohio State University 
Columbus, Ohio 43210 
1. Ab.tr.ct 
Multi-lirbed locmtion in  a *hnd over hmd'l fuhion are 
d 
f r e ,  p s u l t a  frol a RAM I '  ' . .  
/' 
fm handling ~ M I p E g t r d  SltUJIti-1 8uCh 8. atYuetuf.1 f8ilmeS. 
~ 
,----- - - 
t h r e c l i r k d  locomotion/unipulation svsts .  Each limb had ai% d e a e e s  of  / 
,' A w e l l  developed technology of coordination of lulti-limbed l a c a a t w  
' system is now avai lable .  
f r e e d a  and could be  used e i the r  as a l oeaocory  pas pin^ hand-holds. or 81 a 
Mipubtor. Thc foeus of the study m a  kinematic coordination algoriths. 
The presentation w i l l  also include very recent  result. f r a  the Maptire 
Suspension Vehicle Project. The M a p t i r e  %pension Vehicle (AS71 i a  8 legged 
locaotioa system dc8igncd f o r  t e r r e s t r i a l  use which i a  capable of operating in 
t o rp l e t e ly  unstructured ternin i n  e i the r  a te leoperated or opcrator-cm-board 
mode. The ASV features  a 
very advanced coordination md control  system which could readi ly  be adapted t o  
operation i n  space. An i n e r t i a l  package vich a v e r t i c a l  gyro. and rate gyros 
I and accelerometers on t h ree  orthogona1 axes providea body poaition information ' at  high baadvidth. This is c a n a r e d  t o  the operator 's  c-ds. injected via 8 
joystick t o  provide a c-nded force s y s c s  on t he  vehicle's w. This avatem 
is. i n  tarn. decolpoaed by a coordination algorithm i n t o  force c a n d a  to those 
lega which are in  contact v i t h  t h e  proundj The individual l e g  controls are -de 
mtcIIee lmtv-n a force controi mode. when the foot is om the ground. and a 
position veloci ty  mode when the foot i a  h i e 8  returned. This form of control is 
attractive f o r  space applications f u l t i - l i m b e d  ayatema. whether f o r  
locomotion or unipuht ion .  since t vciRht appeara only aa one of the forces 
rctfng om t h e  vehicle bodT and the eoorAination a l g o r i t l n r  are set  up t o  
minimize generation of loada by Rp bs puahinl( aga ins t  one another. 
2. Introduction 
Fu-re development may include autonaous operation. 
Hdti -L¶mbed Systems e m  be used f o r  locomotion over SWce atructurea M vel1 aa for 
?tanipulation. A proven technolow of a r t i f i c i a l  limbed lormotion is now avai lable  (1.21. 
A confifforation which ia well adapted both t o  loccaotion and co u n i p a l a t i o a  is ahom 91 
F i y r e  l a n d  has been atudied in simulation (3.61. 
Limbed locorotion h a  s m r a l  advanta-a f o r  uae over *pace atructurea. rir8t. 8 
limbed svstcm can be wholly e l e c t r i c a l l v  actuated uainc only energy which is r e n m b l e  v i a  
80l.r p.nrls. Tbr actuation ayatem can be configured f o r  r e ~ . o e r a t i o n  s i n h i z i n g  enerltJ 
nquir-nts. Furtbrr.  Lirkd locmocion require8 o n l y  diacrete  bad-hold. and shoald 
require no modification of u n y  atructurea.  F ina l ly ,  limbed aysteas provide great 
f l e x i b i l i t y  pe rn i t r ing  adaptation t o  unexpected situations cauaed either by failure. 
v i t h i n  the l o c m t i o n  s y a t a  i t a e l f .  or by d u r ( e  t o  the atruetare it is nemtiating. 
Technolo&s vhich provide capabi l i ty  for  auton-a i d m t i f i c a t i o n  of hand-holds in  
real t i r  151 are nou under t e a t  a t  several cantera (1.6). This raise8 the p o s s i b i l i v  
that a r m t e  operator need o n l ~  draignate a path uhich wrold be traversed 8utooaouIlT. 
¶a rorb the  IEU tray as is p l a m d  for a Karr rover (71. In tb ia  utmer. direct 
Celeoperation uoald onlT be w e 8 s a r y  when perforrinR un:$atiVc tasks. 
. 
https://ntrs.nasa.gov/search.jsp?R=19890017094 2020-03-20T02:10:14+00:00Z
In this presentat ion the s t a m  of the technologies needed f o r  realitatim of  a 
1- l o c m C i o n / u n i p u l a t i o a  system rill ba rerieved. 
3. A W g e  s t e d  C a n f i y r a c h ~  
Aa is shown in Figure 1. t he  smggested c o n f i p r a t i o n  h8s th ree  limbs. Thia vi11 
8lla l o c m t i o n  with tvo h 8 d s  @ppi.# h8d-bolds  8t 811 tirs.  It  Vi11 8lw allm w e  
of cm rmfpu la t ion  d e s :  8 single -d d e  in which t w o  h8nda g r i p  bud-holds 1e.ting 
one f ree  f o r  u n i p u l a t i o n .  8ud 8 t w  a r r d  cooperatire lode v i t h  one h o d  gripping 8 
h.nbhold. It is expected that .mfpahtion vould be performed in 8 teleoper8tirr -de. 
Locmtlon vould be performed in either a teleoperatire lode. m 8utoamorly with the 
r e v t e  operator designat ing path 8eumts .  as mentioned .bore. R-er. even in the  
telcopcratire d e .  t h e  operator unald c-d only direct ion md rate, ind i r idaa l  l h b  
movements vould be f u l l y  au tou ted .  
o p t i M  g e - t v  Of 8 lid fm locorotion 1s quite c a p a t i b l e  v i t h  t h 8 t  fo r  
u n i p d a t i m  191. I n  f u t .  i f  the f i r s t  j o i n t  ur ia  l a  placed paralle: LO t h e  lonllfcudical 
u t a  of the bodr ( the preferred l amt im d i rec t ion ) .  the sccwd uis i n t e r s e c t s  .he 
f i r s t  8nd is nom81 t o  i t ,  the  th i rd  is p a r a l l e l  t o  t he  second and is placed exactly half  
W 8 y  along the length of the limb. the fourth is also p8rallei t o  the second 8nd thi rd.  the 
f i f t h  in t e r sec t s  t he  fou r th  n o r u l l y  a d  t he  s i x t h  i n t e r s e c t s  t\e f i f t h  n o r u l l y .  aa ahown 
in Figure 2. The configuration is c p t i v l  f o r  both purposes. Korcrer. a three limbed 
system lends i t s e l f  b e t t e r  t o  8 ro ta t iona l ly  a-tric configuration which favors 
omi-direct ional  motion v i t h w t  8 preferred d i r ec t ion .  In such a c m f i g u r 8 t i w  it is 
prefer8ble t o  place t h e  f i r s t  axis of each l i r b  parallel te the axis of s7e tr -y .  as io 
the Wex. f o r  example 121. 
A fmr-legged sys t ea  would hare the rttraction of a1lovinR b i h c e r d  U U i p U h t i O O  
from a firrcr base with t v ~  hands grasping handholds. It could a l s o  be configured a s  8 
b i l a t e r a l l r  synmecric s y s t a  with 8 preferred d i r e c t i o n  of sotion. with son? gains io 
locomotion speed and eff ic iency.  TbLi would. hoverer,  probably only  be an advantage on 
v e m  large s t ruc tu res .  The cost  d d  be t h e  necess i ty  of Coordin8tlng 26 degrees Of 
freedom rather  than 18. and the correaponding increase in  syatca ccmplexicy. 
6. Coordination 
The p r i m ?  problem in ad8pt i r r  l i rbed locorot ion is the a u t o u t i c  cocrdin8tion Of 8 
r e l a t ive lv  l a rge  number of actuated degrees of  freedc= to achieve a deaired body motion. 
A great deal is nov havn about t h i s  problem as 8 r e s u l t  of the Adaptive Smpension 
Vehicle zirolecc f l l .  In part icular .  t he  problem of uainq i r regular .  so-called “free 
gai ts”  t o  a c c m o d a t e  t o  sparse foot-holds or hand-holds is v e l 1  understood. The 
arch::ecture of a s u i t a b l e  f ree-gai t  a l g o r i t h  is shown in Figure 3. With respect  t o  
gai t .  vhic5 is the phasing of l h b  .~.ements. t he  s i t ua t ion  i n  space is, in fact .  much 
s i q i e r  than i n  terrestrial  l o c a a t i o n  since t he re  is no need t o  mintain scabi l i t l r  
against zravitv.  Thus, the sole  d e t e d n a n t  of  t h e  locomotion po ten t i a l  of 8 l i r b  a t  a 
l iven instant  fs its kineaatic u r g i n  [ S I .  This problem w a  exmined in the sbulation 
stud- described in references 131 and [hl. 
7he Adaptive Suspen9ion Vehicle [ I ] .  s h m  in Figure 4. uses an inertial loca l  
guidance sTstem t o  de t ec t  bodv motion a t  high bandwidth. The actual  body rate is compared 
t o  t h e  operator’s commands v i a  a si. axis joyst ick.  The resul t ing e r r o r  is converted into 
a ccmma-.‘cd acce le ra t ion  and. heoce. a c-nded i n e r t i a  force system. Thia i ne r t f a  forde 
tvst- is CmDincd with the weighc of t h e  archfne and decoaposed via a f o r c e  allocation 
algorithm i n t o  cormaanded l eg  forces 18.91. Final lv .  these are  deemposed V i 8  a Jacobim 
t r ans fona t ion  i n t o  ccnmnanded actuator forces.  The use of the legs a s  fo rce  generators i n  
this farnicn r emves  the necessity f o r  soph i s t i ca t ed  drnanic mode1linR of t h e  legs. 
3 . e  i n e r t i a l  sensinR package is a r e l a t i v e l y  simple uni t  consis t ing of a v e r t i c a l  
wrcscoDc. r a t e  qvrostopes on three orthogoml axes,  and accelermeters on the  s p c  axes. 
*if: a d  fntepratfon errors a re  corrected 8 C  Lou 5andvidth by use of pos i t i on  : n f O r ? C b O  
frcm * o i ~ t  gosi t fon sensors on the leg jo in t s .  
“bvicua:*r. a s u b s t f t u t e  voclld have t o  be fwmd for the use ?f qrsvity f o r  a v e r t i c a l  
refere-cc _- z .i3 ic:iem. ?owever, r l e  force cca t r> :  atrategy :s v e y  applicable.  :?. 
t h i s  =mer the uroblen of limbs wortiig aga ins t  each other.  whith is c h a r a c t e r i s t i c  of 
cecperatire.  multi-limbed operarions. is avoided. 
5 .  Sensine 
A l t h z h  :t can Se assumed that  the g-ty of t he  s t ruc tu re  over v’iieh t h e  u c h i n e  vi11 
operate w f l l  be known, except fo r  c i rcaastances in  which the s c p x t u r e  is drraged. it 1s 
still necessarv t o  provide on-board -ing t o  i d e n t i f v  hand-holds and ot’ier features. 
This is Yecessary t o  correct location of t he  hand-hold f o r  i - e r t i a l  srstem d r i f t  and other  
system errors. In f a c t ,  location of l andm~r lu .  perhaps combined with proprioceptive 
posit icn *eI?sor inforaat ion.  can be use.! t o  provide the x c e s s a v  lov bandvidth p s i t i o n  
data  to opdate the i rer t ia l  guid8nce srstem. ha v8s mentioned above. techrologics vhic- 
106 
. . .  
-- 
rill pemit amtartie. red-tfn l d e n t i f i c a t i m  OS much f u t m s  are being developed in 
tbe Adaptive Susp.11.i- V e h i c l e  (ur) 151 md btosmru kad Vehicle ( U V )  161 programs. 
T b  sam~iort rmqpf l ade r  deoeribed in rrfermce 151 is b e i q  wed t o  selct  footholds f o r  
the Adaptive slllpp.i09 Vehicle. It provides a ran- in  angle-angle coordinates 
ac.rmfag a 128 X 128 p i x d  f i e l d  at tu0 fr-s per s e e d .  In the ASV c o n f + p r a t i o n  the 
f i e l d  .c.III).d is 60' in the vertical p h l ~  m d  I' i n  the b o r i Z 0 0 t d .  Ru ALV (u.. 
sunn- raagefioder  4 t h  a s l i g h t l y  d i f f e ren t  f ie ld .  S i r i l a  Imtnments are being u e d  
at mewral other centers. 
'zh necesury technology fm cowersioa of t h e  rsnge imge into s c o n t i n u a u l y  
updated elevation n p  in Cartesian coordixutes hod on the vehicle. and f o r  s e l ec t ion  of 
footholds based 09 that up. bu been developed f o r  the ASV. and w u l d  be  d i r e c t l y  
appliuble to a limbed locaotion system in epace. The scanner. in  t h e  ASV c o a f i y r a t i o a .  
r a l d  k too heavy and bplk?, .ad too expensive i n  pouer requir-ts f o r  we i n  space 
c a u t n t i o a .  Eouever. since this u s  the f i r s t  operatiocull unit. cms ide rab le  
k1-t is possible. Ru meebmical seuming system codd r e a d i l y  be redesil(ned into 
a =cb more c a p u t .  and m c h  lwer power system. Tbc need f o r  higher r e so lu t ioa  a t  
shorter range voold all- we of a leuer poucr Iaaer. 
Video h s e d  terrain d e 1 l i n R  t~CbO01OgieS are also being developed [SI. par t i cu la r ly  
in the AX.? prow-. A t  present. the .rpbsis is on ident i fylog l a r g e  features .  such u 
roads. hrthr development of  t h i s  approach ~ i g h t  u l t i u t e l y  provide models a t  higher 
resolut ion t h n  can be achieved v i t h  the laser scanner approach. 
Aeother important feature  of  the sensing system is the need t o  sense both position 
and fmcr a t  a l l  sctuated joints. In f ac t .  j o i n t  r a t e  sensing is eas i ly  added and is 
use fu l  i n  limb control.  Position. veloci ty ,  and force sensing are used on t he  ASV 
actuators I l l .  Position/race sensing is irporcant f o r  guidance of the limb vhcn i t  is not 
p i p p i n g  a hand- hold. and f o r  inference of tbe position of the  system frol lrnavn 
bnd-hold positions. Force sensing is needed for limbs mpping hand-holds. and fo r  
cooperative u n i p u l a t i o a .  
6. Controls 
A n&r of f ea tu res  of t he  control  system f o r  the proposed machine have a l r eady  been 
described. The proposed system has a hierarchical  archi tecture  shown i n  Figure 5. It is 
h s e d  on techniques proven in the  Mv project.  k is t he  case v i t h  tht system. it is 
intended t h a t  t he  operator could in t e rac t  v i t h  the system at seve ra l  d i f f e r e n t  levels  
[1,3J. A t  t he  highest level .  the operator rould d u i p a t e  path segments t o  be 
auton-sly traversed, as sumested in  Section 1. Figure 6 sh- a composite photo of a 
t b r e t l e g g e d  robot valking over a series of path r e p e n t s  141. It might be noted that  
operation in t h l s  mode vould require  very l i t t l e  h a r d n r e  or wfhrare added to t h a t  needed 
f o r  continuous interaction. This is a result of the  need f o r  automated hand-hold 
selection and coordination f o r  e f f ec t ive  locorotion. 
next level of interaction uould be one in vhich the operator continuously 
c m n d s  body v e l o c i t r  and angular veloci ty  during locomotion v i a  a joystick con t ro l l e r  
similar t o  that used on the ASV [11. This is expected t o  be m e f f e c t i v e  control made fo r  
r e l a t i v e l y  short  traverses. Bote that  hand-hold se l ec t ion  a d  limb coordination w u l d  be 
f u l l y  m t o u t e d  in  t h i s  mode. 
A t  the  next lover leve l  of interaction. the operator would d i r e c t l y  con t ro l  the 
position. r e l a t i v e  t o  the machine body. of one. or tvo hard.. NASA has invest igated 
sfx-uis con t ro l l e r s  su i t ed  t o  t h i s  function 1121. This mde m l d  be used both in 
teleoperatcd manipulation and i n  locomotion vhcn t he  operator f inds  it necessaq to 
d i r e c t l y  control  hand-hold se l ec t ion  and limb md body motion. This might happen. for  
e x p p l e .  h e n  repairing duage .  
It should be noted tha t  t he  proposed s v s t a  has a great deal of inherent f l e x i b i l i t y  
of operation and redundancy. Locowtion is possible  usins only tvo limba. Loas of 
function of several actP.tors could be a c c d a t e d  t o  v i t h  degradation in  perfo-ce. 
but vithout  tot81 l o s s  of function. The use of differin: mixes of a u t o u t e d  and 
teleopetated function alIws adaptation eo a Iarge va r i e tv  of s i t ua t ions .  
7. Canelusion 
A technology of cwrd in8 t lng  multi-limbed systems for l ocaoc ion .  cooperative 
unipuhtion.  .nd f o r  msnipulation v i t h  multi-finger. u l t i - d c f r e e  of freedcm hands is nou 
a v a i h b l e .  It 1s here suggested th t  a u n i p u l a t i o n  s y s t a  v i t h  a t  l e a s t  t h r e e  dual 
pnrpor l i d s  o m  provide an a t t r a c t i v e  m b i l l t y  capabili ty.  Key f ea tu res  of the I . techwlolf €or t h i s  purpose hare been discussed i n  t h i s  paper. 
Uork discussed in  t h l a  paper V.S supported by l U S A  Langley. grant number NAGl-30 md 
by the Defense kbanced Prsearch Projects Agency, contract ntrb.r DAAE07-84-K-R001. 
107 
9. References 
1. 0.ldrOn. K.J. and IlcQIee. R.B.. "The Adaptive Suspensiom Vehicle.'' IEEE Cantrol 
S y s t a s  Magazine. V o l .  6. Ro. 6. December 1986. pp. 7-12. 
2. Barcbolet. 1. "Wetics ?lakes Great Strides.'' h e l e a ?  Engineerin& Vol .  31. Ib. 381. 
pp. 43-44. April 1986. 
3. Kleio. C.A. and Patterson. W.R.. ''Caputer Coordination of L b b  lbtion for Locomtiaa 
of a IILltiple-Armed Robot for Space Assembly." IEEE Tr81'1S8Ctions on Systems, W, sod 
Cybernetics. Vol. -12. So. 6. pp. 913-919. lbmbcrlDccnber 1982. 
Teb, S.C., "Locomotion of  a Three-bgged Robot Over Structural BeamD" M.S. Thesis. 
Dcpntvot of Electrical Engineerins. The Ohio State Unirersicy. Aagust 1981. 
Mviwr: C.A. Klein. 
4. 
5. Zuk. D. Pont. 1.. Pr8nklin. 1. 8od De11'Eva. M. "A System for  Autaaorms Land 
Navigation." Roceedings of  kc ire  Systems Uorkshog. Naval Pootgraduatc School, 
kmterey. blifO171i8. November 6. 1985. 
6. L m o n .  D.T.. Lcvitt. T.S.. kConnel1. C.. Glickaun. J.. "Terrain Wels fo r  an 
Auton-s Land Vehicle," Proceedings of 1386 IEEE In t e rna t iona l  Conference on 
Robotics and Autoration, Vol. 3. pp. 2043-205 1. S8n Fr8ncisco. April 7-10, 1986. 
Klein. G.. Ualdrm. K.. and Cooper. E.. " h r r e n t  Status  of Mission/System D e s i g n  fo r  
8 Mars Rover." U-nned Systems. Vol. 5. No. 1. pp. 28-39. S m e r  1986. 
7. 
A .  Ua;dron. K.J.. Vohnout. V.J.. Pery. A.. and Kccchee. R.B.. "Confiwration Design of 
the Adaptive Suspension Vehicle," Internat ional  Journal of Robotics Research, Pol. 3. 
No. 2. pp. 37-18. S-r 1986. 
9. V i j J Y k U B a r .  R., Ualdron, K.: , and Tsai. M.J. "CCmetriC Optimiz.tion of Seri.1 
Chain h n i p u I a t o r  Structures  for Uorking Volume  and Dexterity." In t e rna t iona l  Journal 
of Robotics Research, Vol. 5. So. 2. S-r 1986. pp. 91-103. 
10. ?IcGhee. R.B. and Orin. D.E.. "A Mathematical Programming Approach t o  Control of Joint  
Posit ions and Torques i n  Legged tacolot ion Systems." The0 and P rac t i ce  of Robots 
and Manipulators. borecki. A., and Kedtior. K. Eds.. z w  York: Elsevier.  pp- 
225-232. 1977. 
11. UJ1drOn. K.J.. "Force and Motion Xanagement i n  Legged Locomotion." IEEE J o u n u l  of 
Robotics and Automation, V a l .  RA-2. No. 4. pp. 216-220, December 1986. 
I t .  Iefctp. A.K. and FlandIgkken. X.. "Generalization of B i t t e r 8 1  Force-Raflectinp 
C&trol of Manipulators.' Proceedinps of Fourth Swposiun on Theow and Pract ice  of 
Robots and Yanfpulators. tsborw. Poland. pp.112-255. September 8-12. 1981. 
108 
Ffpre 1. Proposed configuration of a lfmbed locoaotfoa/.anipulatfon system. 
PREFEXRED l O C O y M 1 o I  DIRECTIOR 
p = q + r  
3 - 
Figure 2. OFtf-1 geometry for a dual purpose limb. 
109 
Ffgure 3. Architecture of free gait algorithm [3] .  
Fipure 0 .  The Adaptive Suspension Vehfclc. 
110 
Figure 5 .  Cdntrol and coordination software architecture.  
interact  ions. 
The dotted boxes indicate  operator 
Figure 6 .  Photo of  s l n u l a t e d  space v e h i c l e  ualtfng over  a s tructural  beam. 
111 


Multi-limbed locomotion systems for space construction and maintenance

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server