• Http://www.research.att.com/~kautz/talks/

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The Role of Optimization andDeduction in Reactive Systems

P. Pandurang NayakNASA Ames Research Center

Brian C. WilliamsMIT

Autonomous Mars Airplane

courtesy NASA Ames

Cassini Maps Titan

• ~ 1 billion $

• 7 years to build

• ~ 150 - 300 ground operators •100 million $

•2 year build

• 0 ground ops

courtesy JPL

The Cost of Autonomy: Cassini

Procedural Executive

Planner &Scheduler

MissionManager

ESL

Monitors

Remote Agent

AMES / JPL

Model-basedExecutive for

Fault Protection

Command dispatchFault protectionAttitude control

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Model-based Execution as a kind of Stochastic Optimal Controller

Controller

Plant

modeidentification

mode reconfiguration

s’(t)

(t)

ffs (t)

gg

o(t)

Models

Livingstone

Goals

• Indirect sensing and control.• Probability, optimality, logic & deduction.

OPSAT

Generate: Best Kernel Assignments– Generate minimal covering of conflicts, in best first order.– Compact encoding grows agenda linearly with checked states

Test: SAT– Unit propagation dominates, ITMS efficiently tracks changes.

generatesuccessors

generatesuccessors

Best First AgendaBest First Agenda Check ConsistencyCheck ConsistencyOptimalOptimalfeasiblefeasible

solutionssolutions

CheckedCheckedsolutionssolutions

ITMSITMS

conflictdatabase

conflictdatabase

Kernel Kernel assignmentsassignments

Remote Agent Experiment

May 17-18th experiment• Generate plan for course correction and thrust • Diagnose camera as stuck on

– Power constraints violated, abort current plan and replan• Perform optical navigation• Perform ion propulsion thrust

May 21th experiment.• Diagnose faulty device and

– Repair by issuing reset. • Diagnose switch sensor failure.

– Determine harmless, and continue plan. • Diagnose thruster stuck closed and

– Repair by switching to alternate method of thrusting. • Back to back planning

See rax.arc.nasa.gov

Remote Agent Experiment

May 17-18th experiment• Generate plan for course correction and thrust • Diagnose camera as stuck on

– Power constraints violated, abort current plan and replan• Perform optical navigation• Perform ion propulsion thrust

May 21th experiment.• Diagnose faulty device and

– Repair by issuing reset. • Diagnose switch sensor failure.

– Determine harmless, and continue plan. • Diagnose thruster stuck closed and

– Repair by switching to alternate method of thrusting. • Back to back planning

See rax.arc.nasa.gov

Remote Agent Team Members

• Douglas Bernard JPL• Steve Chien JPL• Greg Dorais Ames• Julia Dunphy JPL• Dan Dvorak JPL• Chuck Fry Ames• Ed Gamble JPL• Erann Gat JPL• Othar Hansson

Thinkbank• Jordan Hayes

Thinkbank• Bob Kanefsky Ames• Ron Keesing Ames• James Kurien Ames• Bill Millar Ames• Sunil Mohan Formida• Paul Morris Ames

• Nicola Muscettola Ames

• Pandurang Nayak Ames

• Barney Pell Ames

• Chris Plaunt Apple

• Gregg Rabideau JPL

• Kanna Rajan Ames

• Nicolas Rouquette JPL

• Scott Sawyer LMMS

• Rob Sherwood JPL

• Reid Simmons CMU

• Ben Smith JPL

• Will Taylor Ames

• Hans Thomas Ames

• Michael Wagner 4th Planet

• Greg Whelan CMU

• Brian C. Williams Ames

• David Yan Stanford

Outline

• Deep Space One and Remote Agent• Model-based Execution• OPSAT and the ITMS• Model-based Reactive Planning• Space Robotics