Title: The Mystery Talk David E' Smith NASA Ames Research Center desmitharc'nasa'gov
1The Mystery Talk David E. SmithNASA Ames
Research Centerdesmith_at_arc.nasa.gov
2AIPS 2000
Coping with Time Continuous Quantities
3Classical Planning Assumptions
Instantaneous actions No time constraints No
resources No continuous quantities No optimization
Bleak?
4Temporal Planners
Zeno (Penberthy) Trains (Allen) Descartes
(Joslin) IxTeT (Ghallab) HSTS (Muscettola) Europa
(Jonsson et al.)
5Critical Issues
6AIPS 2002 Planning Competition
No SAT planners No ILP planners LPG (local
search on PG) FF, SAPA (forward SS
search) MIPS VHPOP (POCL)
7Significant Progress
distance heuristics
8The Top 6 Reasons NASA Cant Use those
Impressive New Planning Systems(LPG, FF, SAPA,
MIPS, VHPOP, TLPlan, TALPlanner)
9Reason Number 1
- Exogenous conditions events
- Communication windows
- Observation windows
- Lighting conditions
- Orbit insertion
- Celestial events
- Time constraints EVERYWHERE !
10Exogenous Events
Solar-Eclipse Pre _at_528 Eff Visible(),
Forward SS search
528
S0
A
Eclipse
S1
S2
11Exogenous Conditions
Visible(A327)2300, 2320
Visible(A327)
2300
S0
A
Ex
S1
S2
12Why is this Hard?
S0
A
Ex
S1
S2
Heuristic guidance!
13Plan Graph Distance Heuristics
Construct plan graph Use DP to compute distance
estimates for goals
7
2
0
5
5
5
5
0
3
2
1
1
1
1
0
14Adding Exogenous Events
7
2
0
X
5
X
5
5
5
0
0
X
1
1
1
1
0
Non-monotonicity
Actions become impossible Propositions go
away Distances get reset Mutex reappears
15Reason Number 1
- Exogenous conditions events
- Representation
- Search guidance
16Reason Number 2
- Exogenous conditions events
- Over-subscription problems
- Many observations/experiments
- Prioritized
- Limited time, energy, data storage, cryogen,
17Rover Problem
- Given
- Set of goals g1, , gn with values v1, , vn
- Limited resources
- Objective
- Find a good plan
18Rover Problem
5 rocks 5! orderings 25 rocks, can visit 5 6
million orderings
19Which Goals?
- Backward search (Regression/POP/Graphplan)
- 2n goal sets
- Forward search
- guidance?
20Plan Graph Resource Heuristics?
Construct plan graph Use DP to compute resource
estimates for goals
7
2
0
5
5
5
5
0
3
2
1
1
1
1
0
Choose goal set with greatest total utility given
the resources available
21Plan Graph Resource Heuristics?
Construct plan graph Use DP to compute resource
estimates for goals
For Rover Pictures at all locations in 4
steps All estimates from current location
Problem Assumes independence between objectives
22Plan Graph Utility Heuristics?
Construct plan graph Use DP to compute utility
estimates for actions
7
7
10
10
8
5
13
3
3
3
1
1
3
Choose actions that lead toward most utility
23Propagating Utility Tables
5
5
5
25
15
e
q
g
A
B
(10, 15)
(10, 15)
p
t
1
C
r
2
(3, 3)
E
g
(2, 2)
D
s
t
(1, 5)
1
1
e
r
2
1
2
24Plan Graph Utility Heuristics?
Construct plan graph Use DP to compute utility
estimates for actions
7
7
10
10
8
5
13
3
3
3
1
1
3
Problems Complex Assumes independence between
objectives
25Reason Number 2
- Exogenous conditions events
- Over-subscription problems
- Poor search guidance
26Reason Number 3
- Exogenous conditions events
- Over-subscription problems
- Uncertainty
-
Drive (-1)
Dig(5)
Visual servo (.2, -.15)
NIR
27Reason Number 3
- Exogenous conditions events
- Over-subscription problems
- Uncertainty
-
?
10 ,1430
window
power
power
X
X
X
X
Drive (-1)
Dig(5)
Visual servo (.2, -.15)
NIR
28Previous Work
Disjunction
Probability
CGP CMBP C-PLAN Fragplan
Non Observable
Problems
Buridan UDTPOP
Scalability STRIPS model of action no
concurrency no time no resources Discrete action
outcomes Utility
SENSp Cassandra PUCCINI SGP QBF-Plan GPT MBP
C-Buridan DTPOP C-MAXPLAN ZANDER Mahinur POMDPs
Partially Observable
JIC Plinth Weaver PGP MDPs
Fully Observable
WARPLAN-C CNLP
29Can We Make it Discrete?
30Can We Make it Discrete?
Picture
31Can We Make it Discrete?
Collect
32Optimal Value Function
E gt .1 Ah ? .05 Ah ? .02 Ah
E gt .6 Ah ? .2 Ah ? .2 Ah
E gt 10 Ah ? 5 Ah ? 2.5 Ah
E gt .02 Ah ? .01 Ah ? 0 Ah
t ? 900, 1430 ? 5s ? 1s
HiRes
V 10
t ? 1000, 1400 ? 600s ? 60s
E gt 3 Ah ? 2 Ah ? .5 Ah
? 1000s ? 500s
? 60s ? 1s
? 40s ? 20s
Drive (-2)
Dig(60)
Visual servo (.2, -.15)
NIR
Expected Value
V 100
t ? 900, 1600 ? 5s ? 1s
t ? 1000, 1350 ? 600s ? 60s
? 120s ? 20s
20
1320
15
Lo res
Rock finder
NIR
1340
V 50
V 5
10
1400
E gt .12 Ah ? .1 Ah ? .01 Ah
E gt .02 Ah ? .01 Ah ? 0 Ah
E gt 3 Ah ? 2 Ah ? .5 Ah
Power
5
1420
Start time
1440
33Reason Number 3
- Exogenous conditions events
- Over-subscription problems
- Uncertainty
- Continuous time ( resources)
- Continuous outcomes
- Utility
34Reason Number 4
- Exogenous conditions events
- Over-subscription problems
- Uncertainty
- Ramifications
- Physical model
- Switches/valves
35Opening Valves
Open (?valve, ?in, ?out) Pre Open(?valve) Eff
Open(?valve) Pressure(?in) ? Pressure(?out)
36Opening Valves
Pressure(T1)
Open (?valve, ?in, ?out) Pre Open(?valve) Eff
Open(?valve) Pressure(?in) ? Pressure(?out)
37Opening Valves
Open(V1)
Pressure(T1)
Open (?valve, ?in, ?out) Pre Open(?valve) Eff
Open(?valve) Pressure(?in) ? Pressure(?out)
38Opening Valves
Open(V1)
Pressure(T1)
Pressure(P2)
Open (?valve, ?in, ?out) Pre Open(?valve) Eff
Open(?valve) Pressure(?in) ? Pressure(?out)
39Opening Valves
Pressure(P3) ??
Open(V1)
Pressure(T1)
Pressure(P2)
Open (?valve, ?in, ?out) Pre Open(?valve) Eff
Open(?valve) Pressure(?in) ? Pressure(?out)
40Opening Valves
Pressure(P3)
Open(V1)
Open(V2)
Pressure(T1)
Pressure(P2)
Open (?valve, ?in, ?out) Pre Open(?valve) Eff
Open(?valve) Pressure(?in) ? Pressure(?out)
41Opening Valves
Open(V2)
Pressure(T1)
Open (?valve, ?in, ?out) Pre Open(?valve) Eff
Open(?valve) Pressure(?in) ? Pressure(?out)
42Opening Valves
Open(V1)
Open(V2)
Pressure(T1)
Pressure(P2)
Open (?valve, ?in, ?out) Pre Open(?valve) Eff
Open(?valve) Pressure(?in) ? Pressure(?out)
43Reason Number 4
- Exogenous conditions events
- Over-subscription problems
- Uncertainty
- Ramifications
- Physical model
- Switches/valves
- Non-sequential activation
44 Reason Number 5
- Exogenous conditions events
- Over-subscription problems
- Uncertainty
- Ramifications
- Plan revision
- Rolling time horizon
- New goals
- Unexpected state
45 Replan from Scratch?
- Expensive
- Interferes with other unknown plans
46 Reason Number 5
- Exogenous conditions events
- Over-subscription problems
- Uncertainty
- Ramifications
- Plan revision
- Time constraints
- Minimize change
47Reason Number 6
- Exogenous conditions events
- Over-subscription problems
- Uncertainty
- Ramifications
- Plan Revision
- External Reasoning
Drive (x, y)
max
Energy
min
48Reason Number 6
- Exogenous conditions events
- Over-subscription problems
- Uncertainty
- Ramifications
- Plan Revision
- External Reasoning
- Resource models too complex
Simulator
Planner
Simulator
Drive (x, y)
max
Energy
min
49Top 6 Reasons
- Exogenous conditions events
- Over-subscription problems
- Uncertainty
- Ramifications
- Plan Revision
- External Reasoning
50Difficulty?
- Exogenous conditions events
- Over-subscription problems
- Uncertainty
- Ramifications
- Plan Revision
- External Reasoning
E M H E/M M ?
51Questions?