The Artificial Intelligence Section of the Mission Planning and Analysis of the Johnson Space Center has developed a prototype of an expert system for robotic planning. A robot is given a high level goal to perform an action (i.e., swap, adjust, or stow) on a component unit of an object such as a satellite and the Robotic Planner Expert System (RPLANES) generates the necessary goals for arm actions. RPLANES is designed using the Inference Corp. Automated Reasoning Tool (ART) development tool. It resides on a SYMBOLICS 3670. RPLANES and its evolution are described

Grice, Ervin Oneal

English

NASA Technical Reports Server

ROBOTIC PLANNER EXPERT SYSTEM (RPLANES) 
Ervin O'Neal Grice 
A r t i f i c i a l  Intel l igence Section 
Mission Planning And Analysis Division 
Johnson Space Center 
Houston, Texas 77058 
ABSTRACT 2. INITIALIZATION 
T h e  A r t i f i c i a l  I n t e l l i g e n c e  Sec t ion  of 
t h e  Mission Planning and Analysis D i v i -  
s i o n  of t h e  Johnson Space Center has de- 
veloped a p ro to type  of an expe r t  s y s t e m  
f o r  r o b o t i c  planning. A robot is given a 
h i g h - l e v e l  g o a l  t o  perform an a c t i o n  
(i.e. s w a p ,  a d j u s t ,  o r  stow) on a compo- 
nent  u n i t  of  an o b j e c t  such as a s a t e l -  
l i t e  and t h e  Robotic Planner Expert Sys- 
t e m  (RPLANES) g e n e r a t e s  t h e  necessa ry  
g a a l s  f o r  a r m  a c t i o n s .  RPLANES i s  de- 
s i g n e d  u s i n g  t h e  I n f e r e n c e  Corpora- 
t i o n  Automated Reasoning Tool (ART) de- 
velopment t o o l .  I t  resides on a SYMBOL- 
I C s  3670. This paper  describes RPLANES 
and i ts  evolution. 
1. INTRODUCTION 
Robotic technology is  an a n t i c i p a t e d  es- 
s e n t i a l  du r ing  t h e  Space S t a t i o n  opera- 
t i o n a l  era. Robots w i l l  be given high- 
l e v e l  g o a l s  t o  perform t h a t  w i l l  be ac- 
complished by e x e c u t i n g  a series of  
lower- level  g o a l s .  These lower- level  
g o a l s  and t h e  o r d e r  of performance are 
derived by a planner  expert  system. T h e  
i n i t i a l  development e f f o r t  f o r  the  proto- 
type detailed i n  t h i s  paper i s  a t t r i b u t e d  
t o  t h e  Sequence Automation Research Group 
of t he  Jet Propuls ion Laboratory of t h e  
C a l i f o r n i a  I n s t i t u t e  of  Technology. The 
f o r t y - e i g h t  r u l e s  e x p e r t  system had a 
l imi ted  c a p a b i l i t y  of planning t h e  two 
arm a c t i o n s  of a robot  t o  swap a compo- 
nent u n i t  from a simple s a t e l l i t e  s t r u c -  
t u r e  (Figure 1) by dismantling a l l  compo- 
nents  of t h e  s t r u c t u r e .  Enhancement of  
t h i s  expe r t  system has evolved t o  eighty- 
two r u l e s  t o :  
a. Performing a swap, a d j u s t ,  o r  stow 
goal.  
b. Dismantl ing on ly  t h o s e  component 
u n i t s  r equ i r ed  t o  reach t h e  t a r g e t  
component. 
c. Defining a more complex s a t e l l i t e  
s t r u c t u r e  (Figure 2). 
2.1 Define The Architectural 
Structure Of The Serviceable 
Object 
Using t h e  Inference Corporation Automated 
Reasoning Tool (ART) concept of schemata, 
t h e  a r c h i t e c t u r a l  s t r u c t u r e  of t h e  ser- 
v i c e a b l e  o b j e c t  is defined.  T h e  rela- 
t i o n s  "comes-before" and i t s  i n v e r s e  
"comes-after" are defined and employed t o  
de f ine  t h e  a r c h i t e c t u r a l  i n t e g r i t y  of a l l  
components within t h e  s t r u c t u r e .  Figure 
2 i s  a diagram of t h e  Laser Bat t les ta-  
t i o n  used i n  t h i s  prototype and Figure.3 
d e t a i l s  t h e  d e f i n i t i o n s  of  t h e  "doorl"  
a r ch i t ec tu re  using schemata. 
2.2 Define The Serviceable Component 
Units 
Each serviceable component u n i t  of  t h e  
o b j e c t  is def ined  w i t h  a c o l l e c t i o n  of  
a t t r i b u t e  s l o t s  (Figure 4 ) .  Spec i f i c  ac- 
t i o n s  t ha t  can be performed on the compo- 
nent  and the  a c t i o n  by t h e  robot i s  de- 
f ined.  In  addi t ion t o  def ining the  compo- 
nen t  u n i t s  of  the o b j e c t ,  replacement 
u n i t s  used i n  a swap ac t ion  are de f ined  
having a cu r ren t  l oca t ion  of a "tool-box" 
o r  "storage-bin" (Figure 5 ) .  
2.3 Define The Initial State Of The 
Robot 
The i n i t i a l  s ta te  of the  robot i s  def ined 
u s i n g  schemata and a t t r i b u t e  s l o t s  
(Figure 6). The l e f t  and r i g h t  arms are 
s t a t u s e d  "free" and the  l e f t  and r i g h t  
arms a r e  de f ined  as empty by  a s s i g n i n g  
t o o l  va lues  of  "nul l - tool- l ' l  and "nu l l -  
tool-2" t o  each arm respect ively.  
2.4 Define The Action Scripts 
An a c t i o n  on a component u n i t  can be de- 
scribed as a sequence of  sub -ac t ions .  
For example a swap a c t i o n  of a component 
u n i t  involves: 
293 
https://ntrs.nasa.gov/search.jsp?R=19880007862 2020-03-20T07:31:41+00:00Z
a. 
b. 
d. 
e. 
C. 
Rendezvousing with the component 
unit to be swapped. 
Removing the component unit. 
Stowing the component unit. 
Unstowing the replacement component 
unit. 
Replacing with the new component 
unit. 
If a node is used to represent each sub- 
action, this sequence of nodes represents 
the action script. Each node in the 
script and its order within the script is 
defined using schemata and attribute 
slots (Figure 7 ) .  
3. USER INTERFACE 
RPLANES employs mouse and menus for user 
interface (Figure 8 ) .  The serviceable 
object definition, type of action to per- 
form, and the component unit (s) involved, 
are defined by the user. Any conflicts 
in these selections are determined by the 
expert system and redefinition is re- 
quired. 
4. GENERATING TEE SUB-GOALS 
4.1 Logically Dismantle The Required 
Component Units 
Based upon the architectural structure of 
the object defined during initialization, 
all serviceable component units that 
"comes-before" the target component unit 
nust be dismantled. A node representing 
each component unit along with attribute 
slots are placed in a knowledge base. 
4.2 Retrieve The Action Script . 
Following the logical dismantling of the 
necessary component units, the specified 
action script is retrieved. A node and 
attribute slots representing the sequence 
of steps in the specified action script 
are placed in the knowledge base. A 
"comes-after" relationship attribute is 
associated with this set of nodes to de- 
note the order of the action on the tar- 
get component unit with respect to the 
dismantling of preceding units. 
4.3 Logically Reassemble The 
Required Component Units 
Once the action script has been logically 
performed on the target component unit, 
the object must be reassembled. Nodes 
representing each unit and the attribute 
slots detailing each node are also placed 
in the knowledge base. Reassembling the 
component units is performed in reverse 
with respect to dismantling. 
4.4 Determine The Robot's Arm 
Actions 
RPLANES assumes the robot has two arms 
that can work in parallel and/or seri- 
ally. Progressing through the ordered 
nodes constructed in the knowledge base, 
the specific arm to be used by the robot, 
the tool required, and the component unit 
to service is determined. 
5. OUTPUT 
Using the nodes of attribute slots gener- 
ated in the 'knowledge base above, the 
robot primitives (commands) are gener- 
ated. The output is displayed to CRT 
(Figure 9). 
6. CONCLUSION 
Development of this prototype demon- 
strates the planner expert system func- 
tional capabilities. Applications em- 
ploying graphics and hardware with the 
capability to input and execute these 
generated primitives are potential exten- 
sions. 
7. ACXNOWLEDGEMENTS 
I would like to thank Mark Rokey of the 
Sequence Automation Research Group of the 
Jet Propulsion Laboratory for the base- 
line concepts expanded within the expert 
system and Dr. Joseph Giarratano of the 
University of Houston-Clear Lake for the 
design of the laser battlestation used in 
the prototype expert system. 
8. REFERENCE 
1. Inference Corporation, "AUTOMATED 
REASONING TOOL REFERENCE MANUAL," 
5300 W. Century Blvd., Los Angeles, 
Ca. 90045. 
294 
1 B=T I 
FIGURE - 1 SIMPLE SATELLITE 
111 
(de?scb.u laser-doorl-partel .. 
(strrcture-type laser-station) 
(part-type scr.rl) 
(COm*S-be?OFe lasmrdoorl-parti) 
(instence-o? part-Iter)) 
(structure-type laser-station) 
(part-type scr..U) 
(COI*S-befo~* laser-doorl-parti) 
(instance-of part-iter)) 
(structure-type laser-station) 
(part-type doorl) 
(CMOS-before laser-doorl-partz) 
(Instance-of part-stem)) 
(structure-type laser-station) 
(Pwt-type blanket) 
(Comes-before laserdoorl-parts) 
(Coms-be?ore lasmr-doorl-part4) 
(cM*s-befo+* laser-domrl-parts) 
(instance-of part-iter)) 
(defsch.u laser-door1-partbI .. 
(defsch- laser-doorl-part1 .. 
(deCscb.u Iaser-doorl-part9 .* 
(defsch.u laser-doorl-partJ .. 
(structure-type laser-station) 
(part-type radar-antenna-cable) 
(comes-before laserdoorl-part4) 
(CoWs-beCOVe laser-doorl-partb) 
(comes-before laserdoorl-part7) 
(comes-before lasmr-doorl-parts) 
(instmce-of part-iter)) 
(dafsclH. laser-doorl-part4 .* 
(structure-tqpe laser-station) 
(part-type radar-porer-cable) 
(comes-belore Iaser-doorl-~art.6) 
(corms-before laser-doorl-partE) 
(cores-before laser-doorl-part9) 
( Instanc .-of part-i tar I 1 
WoRl 
4defscL.u laser-doorl-part5 
(~tru~tur~-tqpe laser-station) 
(part-type radar-rt-cable) 
(comes-before laser-doorl-part4) 
(COr*S-befOVe laser-doorl-partb) 
(comes-before laser-doorl-parte) 
(instance-of part-iter) ). 
(structure-type laser-station) 
(~8rt-tupe r a d a r i e c e i v e r t r a n s r i t t e r l  
(Comes-before laser-doorl-parte) 
(cores-after laser-doorl-partz) 
(instance-of part-item)) 
(defschmu laser-doorl-part7 
(structure-type laser-station) 
(part-type radar-antenna) 
(c~es-a?ter laserdoorl-p~rtb) 
(comas-after 1aswr-doorl-partS~ 
(instance-of part-item)) 
'defscheu laser-doorl-parte 
(structure-tup. laser-station) 
(part-typa cOI.creceivertrans-itter) 
(cores-after laser-doorl-part6) 
(instance-ot part-iter)) 
(structure-type laser-station) 
(part-type coam-~nt~nna-cable) 
(Cores-before laser-doorl-parte) 
(Cores-be?ore laser-doorl-partlo) 
(instance-of part-iter)) 
(defsch.u laser-doorl-part10 .. 
(structure-type laser-station) 
(part-tups corcantenna) 
(cores-after laser-doorl-parte) 
(instance-o? part-iter)) 
(defScbDN laser-doorl-part6 .. 
(4wfsch.u laser-doorl-p8rt9 .- 
ORIGINAL PAGE 
OF POOR QKJW 
295 
(4efsch.u nerceble .. 
(fuilm cable) 
(first-ckoice-arm left-arm) 
(second-choice-arm right-arm) 
(.*tu. attached) 
(current-location toolbox) 
(actions-by-this-object-slot (slot-hormy multiP1eralues) 
(replace pluB-in) 
(remove slide-out) 
(stor fold) 
(unstor slide-out) 1 
(state-or-location-efter-action-slot (slot-hm-aany multiple-values) 
(r*plaCe d e i i  i te) 
< remove sate11 i tm ) 
(stor tool-box) 
(unstou f reespace) )  
(tool Islot-borreny multipleralues) null-tool-1 null-tool-211 
FIGURE - 5 REPLACEXENT UNITS DEFINITION 
(defsckmma door1 
(family door) 
(first-choice-arm right-arm) 
(second-choice-arm left-arm) 
(status attached) 
(current-location laser-station) 
(act ions-by-this-obJ.ct- . lot  (slot-ho-ny mu1tiple~alu.s) 
(detach open1 
(attach close) 
(edJust-in close) 
(adJust-out open) 
(stor stor) 
tunstor unstor) 
(replace attach) 
(remove detach)) 
(state-or-location-efter-action-slot (slot-horrany multiple-values) 
(detach laser-station) 
(attach laser-station) 
(8dJust-in closed) 
(adjust-out opened) 
(stor rack) 
(unstor f reespace)  
(reelace hser-stetion) 
( r i w v e  reek)) 
(tool (slot-horuny wltipleralues~ null-tool-1 null-tool-2)) 
(defschen scrercharecteristics 
( f u i l y  screvl 
(actions-by-this-obJect-slot (slot-horuny mu~tiple-v~lue~) 
(detach unscrer) 
(remove unscrw) 
(ad JUst-in scrw) 
(adlust-out UnsCrw) 
(stnu slide-in) 
(unstor slidrout) 
(attach screr) 
( r . P l 8 C O  SCT.)) 
(detach outset) 
(stat.-or-location-efter-action-slot (slot-hourany multipleralues) 
i;ii;ve tiolbox) 
(adJust-in inset) 
Istor tool-box) 
(unstou freespace1 
(attach inset) 
(replace inset)) 
(WdJUSt-OUt 0UtS.t) 
(tool screrlrivwr)) 
Idefscheu screw1 .. 
(tivst-choice-arm right-*rl) 
(s.cond-choice-erm left-arm) 
(Instance-of screu-characteristics) 
(current-location inset) 
(status attached11 
FIGURE 4 SERVICEABLE COI4TO”T DEFINITION 
(4efsche.r nerdoor .- 
( f u i l y  door) 
(Ciret-choice-err riskt-err1 
(second-ckoice-arm left-arm1 
(status attacb.4) 
(current-location rack) 
( .CttOnS-bU-tki . -obJ.ct- . lot (s1ot-h-ny multiple-values) 
(replace attach) 
(adjust-in vusk) 
(adJust-out p u l l )  
(stor stor) 
(unstw unstw) 
(remove dmtach)) 
(state-orlocation-after-action-slot (slot-houuny multi@le-v.lues) 
(7epl.C. S.t*llit.) 
(adjust-in recb) 
(adJust-out rack) 
(stow rack) 
(unstor treespece) 
(remove satellite)) 
(tool (slot-horunq wltlp1e-velues) null-tool-1 null-tool-2)) 
ORIGINAL PAGE IS 
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296 
( d e t s c h e u  s c r i p t  *Base d e t i n i t i o n  o t  a s c r i p t  schema. 
( s c r i p t - t y p e )  
( s c r i p t - s t a t e )  
(comes-betore)) 
( s c r i p t - o b j e c t )  
111- 7- .HIIII"w-H. 
111 Were i s  t h e  d e t i n i t i o n  0, t h e  n e t r o r b  0 ,  nodes which d e s c r i b e  
I l l  a W a c t i o n .  T h i 8  i s  t y p i c a l  a? rbat rill b e  u n y  sucb 
1 1 1  : s c r i p t - l i k e  ACTION n e t w r b s -  in  t h e  t ina l  s y s t e m  
111--- -- 
( d e t s c h e u  s u p - s o u r c e  .- 
( i n s t a n c e - o t  s c r i p t )  
( s c r i p t - t y p e  s u p )  
( s c r i p t i t a t e  rendexvous)  
(cores-betore sup-1 )  1 
( instance-ot  s c r i p t )  
( s c r i p t - o b j m c t  s u p p e e )  
( s c r i p t - t y p e  s u p )  
( s c r i p t - s t a t e  r m v e )  
(cMms-be?ore sup-2 )  ) 
(SCript-ObJeCt source)  
( d e t s c h ~ .  s u p 1  
(6etsch.u s u p - a  =- 
( i n s t a n c e - ~ ?  s c r i p t )  
( s c r i p t - o b j e c t  storme) 
(scr ipt- tup.  s u p )  
( s c r i p t - s t a t e  stmu) 
(cores-betore s u p - 3 ) )  
(instancm-ot s c r i p t )  
( s c r i p t - o b j e c t  ur istouer)  
( s c r i p t - t y p e  s u p )  
( s c r i p t - s t a t e  u n s t o u )  
(Comms-betore su8p-J) )  
( i n s t a n c e - o t  s c r i p t )  
( s c r l p t - t y p e  s u p )  
( s c r i p t - s t a t e  replace) 
(comes-betore s u p - s i n k ) )  
(detschema s u p - s i n k  ". 
( i n s t a n c e - o t  s c r i p t )  
( s c r i p t - t y p e  s u p )  
( s c r i p t - s t a t e  rendezvous)  
( d m t s c h e u  suap-3 ." 
( d e t s e h e u  s u p - 4  .. 
(SCript-ObJ.Ct S u p p e r )  
( p h a s e  3 u r k )  
(SCript-ObJect  s i n k ) )  
I 
( d e t s c h e u  l e t t - a r m  .. 
( s t a t u s  free)) 
( d e t s c h m u  r i g h t - a r m  "- I 1 
I 
( s t a t u s  tree)) 
( d e t s c h m u  s c r m r d r i v e r  .- 
( s t a t u s  tree)) 
( d e t s c h m u  n u l l - t o o l - 1  .- 
(held-by r i g h t - a r m )  
( s t a t u s  frem)) 
( d e t s c h m u ~ n u l l - t o o l - 2  .. 
(held-by l e t t - e r r )  
( s t a t u s  fres)) 
FIGURE - 6 I N I T I A L  ROBOT STATE 
FIGURE - 7 ACTION SCRIPT DEFINITION 
m SERVICEABLE OBJECT 
OPERATION lU PERFORM I 
BLANKET 
WOR 
CABLE-1 
SCREW-1 
scxm-2 
las 
RADAR-RECEIVER-TRANSMITTER 
C Q . J - m A  
RADAR-ANTENNA-CABLE 
UNIT To BE SWWPED 
BLANltET 
DOOR 
=LE-1 
SCREW-1 
SCREW-2 
R1DAR-RECEIVER-TSMIl"l'ER 
COIQ4-ANTENNA 
RADAR-ANTENNA-CABLE 
RGPLACEMENT UNIT 
DOOR 
ULBLE-1 
SCREW-1 
SCREW-2 
MEB , 
: RADAR-RECEIVER-TRANSMITTER 
j COWANTENNA 
! RADAR-ANTENNA-CAUE 
NEW-CABLE 
NEW-SCREW 
NEW-HEB 
NEW-RECEIVER 
NEW-ANTENNA 
FIGURE - 8 USER INTERFACE MENUS 
ORIGINAL PAGE IS 
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FIGURE - 9 SAMPLE OUTPUT 
297 


Robotic planner expert system (RPLANES)

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