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Information Sharing for Distributed Planning. Prasanna Velagapudi. Large Heterogeneous Teams. 100s to 1000s of robots, agents, people Complex, collaborative tasks Dynamic, uncertain environment Joint planning intractable. Scaling Team Planning.
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Information Sharing forDistributed Planning Prasanna Velagapudi AAMAS 2010 - Doctoral Symposium
Large Heterogeneous Teams • 100s to 1000s of robots, agents, people • Complex, collaborative tasks • Dynamic, uncertain environment • Joint planning intractable AAMAS 2010 - Doctoral Symposium
Scaling Team Planning • Independent planners: can’t account for teammates • Existing work: needs specific structure or doesn’t scale to these sizes • DPC, Prioritized Planning • JESP, Factored MDP, ND-POMDP AAMAS 2010 - Doctoral Symposium
Iterated Distributed Planning • Factor the problem, enumerate interactions • Compute independent plans & potential interactions • Exchange messages about interactions • Use exchanged information, improve local model AAMAS 2010 - Doctoral Symposium
Iterated Distributed Planning • Factor the problem, enumerate interactions • Compute independent plans & potential interactions • Exchange messages about interactions • Use exchanged information, improve local model ? AAMAS 2010 - Doctoral Symposium
Iterated Distributed Planning • Factor the problem, enumerate interactions • Compute independent plans & potential interactions • Exchange messages about interactions • Use exchanged information, improve local model ? AAMAS 2010 - Doctoral Symposium
Iterated Distributed Planning • Factor the problem, enumerate interactions • Compute independent plans & potential interactions • Exchange messages about interactions • Use exchanged information, improve local model AAMAS 2010 - Doctoral Symposium
A Tale of Two Distributed Planners Distributed Prioritized Planning (DPP) L-TREMOR AAMAS 2010 - Doctoral Symposium
Distributed Prioritized Planning AAMAS 2010 - Doctoral Symposium
Multiagent Path Planning Start Goal AAMAS 2010 - Doctoral Symposium
Multiagent Path Planning AAMAS 2010 - Doctoral Symposium
Prioritized Planning • Assign priorities to agents based on path length [van den Berg, et al 2005] AAMAS 2010 - Doctoral Symposium
Prioritized Planning • Plan from highest priority to lowest priority • Use previous agents as dynamic obstacles [van den Berg, et al 2005] AAMAS 2010 - Doctoral Symposium
Distributed Prioritized Planning Parallelizable & Equivalent AAMAS 2010 - Doctoral Symposium
Large-Scale Path Solutions AAMAS 2010 - Doctoral Symposium
Large-Scale Path Solutions AAMAS 2010 - Doctoral Symposium
DPP Results Fewer Sequential Plans AAMAS 2010 - Doctoral Symposium
DPP Results Fewer Sequential Plans Longer Planning Time AAMAS 2010 - Doctoral Symposium
Why does this happen? • Prioritized Planning • DPP Longest planning agents might replan multiple times A A B B C C Individual agent planning times varied by >2 orders of magnitude D D Solution 1: Prioritize by plan time? Solution 2: Incremental Planning AAMAS 2010 - Doctoral Symposium
Summary of DPP • Observable, certain world • Only one type of interaction: collision • Far fewer sequential planning iterations • Incremental planning may reduce execution time AAMAS 2010 - Doctoral Symposium
L-TREMOR AAMAS 2010 - Doctoral Symposium
A Simple Rescue Domain Unsafe Cell Rescue Agent Clearable Debris Narrow Corridor Victim Cleaner Agent AAMAS 2010 - Doctoral Symposium
A Simple (Large) Rescue Domain AAMAS 2010 - Doctoral Symposium
Distributed POMDP with Coordination Locales (DPCL) • Often, interactions between agents are sparse Only fits one agent Passable if cleaned [Varakantham, et al 2009] AAMAS 2010 - Doctoral Symposium
Distributed POMDP with Coordination Locales (DPCL) • Define coordination locales (CLs) where POMDP model functions are not independent: <S, A, Ω, P, R, O> (states) (actions) (obs.) (transition)(reward)(obs. fn) [Varakantham, et al 2009] AAMAS 2010 - Doctoral Symposium
Distributed POMDP with Coordination Locales (DPCL) • Define coordination locales (CLs) where POMDP model functions are not independent: Outside CL: (typical) Sglobal R1, P1, O1 R2, P2, O2 S1, A1 S2, A2 [Varakantham, et al 2009] AAMAS 2010 - Doctoral Symposium
Distributed POMDP with Coordination Locales (DPCL) • Define coordination locales (CLs) where POMDP model functions are not independent: Inside CL: (interaction) Sglobal R12, P12, O12 S1, A1 S2, A2 [Varakantham, et al 2009] AAMAS 2010 - Doctoral Symposium
TREMOR [Varakantham, et al 2009] AAMAS 2010 - Doctoral Symposium
L-TREMOR Distributed & Parallelizable AAMAS 2010 - Doctoral Symposium
Preliminary Results – Joint Utility N = 100 (structurally similar to N=10) N = 6 N = 10 AAMAS 2010 - Doctoral Symposium
Preliminary Results – Timing AAMAS 2010 - Doctoral Symposium
Preliminary Results – Model Accuracy R = 0.804 AAMAS 2010 - Doctoral Symposium
Current Issues • Oscillations in solutions • Discovery of relevant locales ? AAMAS 2010 - Doctoral Symposium
Summary of L-TREMOR • Partially-observable, uncertain world • Multiple types of interactions • Role-allocation of tasks • Improvement over independent planning • Handles large problems • Next steps: improving convergence AAMAS 2010 - Doctoral Symposium
Conclusions • Two approaches to distributed planning • DPP: approaching centralized performance • L-TREMOR: exceeding joint tractability • Analogous strategies for distributing planning • Both iterate independent planners • Both exchange messages about states, actions AAMAS 2010 - Doctoral Symposium
Future Work • Generalized framework for distributed planning through iterative message exchange • Reduce necessary communication • Better search over task allocations • Scaling to larger team sizes AAMAS 2010 - Doctoral Symposium