Robotic Space Explorers: To Boldly Go Where No AI System Has Gone Before A Story of Survival J/6.834J September 19, 2001
Copyright B. Williams J/6.834J, Fall 01 Readings and Assignment Model-based Agents: Remote Agent: to Boldy Go Where No AI System Has Gone Before, N.Muscettola, P. Nayak, B. Pell and B. Williams, Artificial Intelligence 103 (1998) Remote Agent: to Boldy Go Where No AI System Has Gone Before, Partial Order Planning (for next lecture) AIMA Chapter 11, Chapter 10, section on unification algorithm. For Problem Set 3: Path Planning Using Lazy PRM, R. Bohlin and L. Kavraki, ICRA 2000.Path Planning Using Lazy PRM,
Copyright B. Williams J/6.834J, Fall 01 Outline Motivation Model-based autonomous systems Remote Agent Example
Cassini Maps Titan courtesy JPL 7 year cruise ~ ground operators ~ 1 billion $ 7 years to build A Capable Robotic Explorer: Cassini 150 million $ 2 year build 0 ground ops Faster, Better, Cheaper
courtesy JPL ``Our vision in NASA is to open the Space Frontier... We must establish a virtual presence, in space, on planets, in aircraft and spacecraft.’’ - Daniel S. Goldin, NASA Administrator, May 29, 1996
Copyright B. Williams J/6.834J, Fall 01 Four launches in 7 months Mars Climate Orbiter: 12/11/98 Mars Polar Lander: 1/3/99 Stardust: 2/7/99 QuickSCAT: 6/19/98 courtesy of JPL
Copyright B. Williams J/6.834J, Fall 01 Miscommanded: Mars Climate Orbiter Clementine courtesy of JPL Spacecraft should be embodied with a survival instinct
Copyright B. Williams J/6.834J, Fall 01 Vanished: Mars Polar Lander Mars Observer courtesy of JPL Spacecraft require commonsense…
Copyright B. Williams J/6.834J, Fall 01 Traditional spacecraft commanding
Houston, We have a problem... courtesy of NASA Quintuple fault occurs (three shorts, tank-line and pressure jacket burst, panel flies off). Mattingly works in ground simulator to identify new sequence handling severe power limitations. Mattingly identifies novel reconfiguration, exploiting LEM batteries for power. Swaggert & Lovell follow novel procedure to repair Apollo 13 lithium hydroxide unit.
What Makes this Difficult: Cassini Case Study courtesy JPL
Reasoning through interactions is complex
Copyright B. Williams J/6.834J, Fall 01 Reconfiguring for a Failed Engine Fuel tank Oxidizer tank
Copyright B. Williams J/6.834J, Fall 01 Reconfiguring for a Failed Engine Open four valves Fuel tank Oxidizer tank
Copyright B. Williams J/6.834J, Fall 01 Reconfiguring for a Failed Engine Valve fails stuck closed Open four valves Fuel tank Oxidizer tank
Copyright B. Williams J/6.834J, Fall 01 Reconfiguring for a Failed Engine Fire backup engine Valve fails stuck closed Open four valves Fuel tank Oxidizer tank
Copyright B. Williams J/6.834J, Fall 01 Challenge: Thinking Through Interactions Programmers must reason through system-wide interactions to generate codes for: command confirmationcommand confirmation goal tracking goal tracking detecting anomalies detecting anomalies isolating faults isolating faults diagnosing causes diagnosing causes hardware reconfig hardware reconfig fault recovery fault recovery safing safing fault avoidance fault avoidance control coordination control coordination Equally problematic at mission operations level
Copyright B. Williams J/6.834J, Fall 01 Outline Motivation Model-based autonomous systems Remote Agent Example
Copyright B. Williams J/6.834J, Fall 01 Programmers generate breadth of functions from commonsense models in light of mission goals. Model-based Programming Program by specifying commonsense, compositional declarative models. Model-based Planning & Execution Provide services that reason through each type of system interaction from models. on the fly reasoning requires significant search & deduction within the reactive control loop. Model-based Autonomy
courtesy of NASA Quintuple fault occurs (three shorts, tank-line and pressure jacket burst, panel flies off). Mattingly works in ground simulator to identify new sequence handling severe power limitations. Mattingly identifies novel reconfiguration, exploiting LEM batteries for power. Swaggert & Lovell work on Apollo 13 emergency rig lithium hydroxide unit. Styles of Thinking Through Interactions
Quintuple fault occurs (three shorts, tank-line and pressure jacket burst, panel flies off). Mattingly works in ground simulator to identify new sequence handling severe power limitations. Mattingly identifies novel reconfiguration, exploiting LEM batteries for power. Swaggert & Lovell work on Apollo 13 emergency rig lithium hydroxide unit. Multiple fault diagnosis of unexperienced failures. Mission planning and scheduling Hardware reconfiguration Scripted execution Styles of Thinking Through Interactions
Copyright B. Williams J/6.834J, Fall 01 Example of a Model-based Agent: Goal-directed First time correct projective reactive Commonsense models Heavily deductive Scripts component models Goals Diagnosis & Repair Mission Manager ScriptedExecutive Planner/Scheduler Remote Agent Mission-level actions & resources
Copyright B. Williams J/6.834J, Fall 01 Conventional Wisdom: Reservations about Intelligent Embedded Systems “[For reactive systems] proving theorems is out of the question” [Agre & Chapman 87]
Copyright B. Williams J/6.834J, Fall 01 Many problems aren’t so hard
Copyright B. Williams J/6.834J, Fall 01 Generate Non-conflicting Successor Generate Non-conflicting Successor Candidates with Increasing cost SAT Explanation for Conflicts Explanation for Conflicts Developed RISC-like, deductive kernel (OPSAT) How can general deduction achieve reactive time scales? Solutions
Copyright B. Williams J/6.834J, Fall 01 Transition Systems + Constraints + Probabilities Closed Valve Open Stuckopen Stuckclosed OpenClose inflow = outflow = 0 Can model-based agents perform many different types of reasoning from a common model?
Copyright B. Williams J/6.834J, Fall 01 Outline Motivation Model-based autonomous systems Remote Agent Example
Copyright B. Williams J/6.834J, Fall 01 Real-Time Execution Flight H/W Fault Monitors Planning Experts (incl. Navigation) Remote Agent Architecture Ground System RAX Manager Diagnosis & Repair Mission Manager Scripted Executive Planner/Scheduler Remote Agent RAX_START
Copyright B. Williams J/6.834J, Fall 01 Real-Time Execution Flight H/W Fault Monitors Planning Experts (incl. Navigation) Ground System RAX Manager Diagnosis & Repair Mission Manager ScriptedExecutive Planner/Scheduler Remote Agent RAX_START Executive requests plan
Copyright B. Williams J/6.834J, Fall 01 Real-Time Execution Flight H/W Fault Monitors Planning Experts (incl. Navigation) Ground System RAX Manager Diagnosis & Repair Mission Manager Scripted Executive Planner/Scheduler Remote Agent RAX_START Remote Agent Architecture
Copyright B. Williams J/6.834J, Fall 01 Real-Time Execution Flight H/W Fault Monitors Planning Experts (incl. Navigation) Ground System RAX Manager Diagnosis & Repair Mission Manager Scripted Executive Planner/Scheduler Remote Agent RAX_START Mission manager establishes goals, planner generates plan
Copyright B. Williams J/6.834J, Fall 01 Real-Time Execution Flight H/W Fault Monitors Planning Experts (incl. Navigation) Ground System RAX Manager Diagnosis & Repair Mission Manager ScriptedExecutive Planner/Scheduler Remote Agent RAX_START Executive executes plan
Copyright B. Williams J/6.834J, Fall 01 Real-Time Execution Flight H/W Fault Monitors Planning Experts (incl. Navigation) Ground System RAX Manager Diagnosis & Repair Mission Manager Scripted Executive Planner/Scheduler Remote Agent RAX_START Diagnosis system monitors and repairs
courtesy JPL Walk Through of Cassini Saturn Orbital Insertion
Copyright B. Williams J/6.834J, Fall 01 Real-Time Execution Flight H/W Fault Monitors Planning Experts (incl. Navigation) Ground System RAX Manager Diagnosis & Repair Mission Manager Scripted Executive Planner/Scheduler Remote Agent RAX_START Plan for Next Time Horizon
Copyright B. Williams J/6.834J, Fall 01 Thrust Goals Attitude Engine Power
Copyright B. Williams J/6.834J, Fall 01 Thrust Goals Attitude Point(a) Engine Off Delta_V(direction=b, magnitude=200) Power Mission Manager Sets Goals over Horizon
Copyright B. Williams J/6.834J, Fall 01 Thrust Goals Attitude Point(a) Engine Off Delta_V(direction=b, magnitude=200) Power Planner Starts
Copyright B. Williams J/6.834J, Fall 01 Thrust Goals Attitude Point(a) Engine Thrust (b, 200) Off Delta_V(direction=b, magnitude=200) Power
Copyright B. Williams J/6.834J, Fall 01 Thrust Goals Attitude Point(a) Engine Delta_V(direction=b, magnitude=200) Power Thrust (b, 200) Off
Copyright B. Williams J/6.834J, Fall 01 Thrust Goals Attitude Point(a) Engine Delta_V(direction=b, magnitude=200) Power Thrust (b, 200) Off
Copyright B. Williams J/6.834J, Fall 01 Thrust Goals Attitude Point(a) Engine Delta_V(direction=b, magnitude=200) Power Off Thrust (b, 200)
Copyright B. Williams J/6.834J, Fall 01 Point(b) Thrust Goals Attitude Point(a) EngineOff Delta_V(direction=b, magnitude=200) Power Thrust (b, 200) Off
Copyright B. Williams J/6.834J, Fall 01 Thrust Goals Attitude Point(a) Point(b) Engine Thrust (b, 200) Off Delta_V(direction=b, magnitude=200) Power Off
Copyright B. Williams J/6.834J, Fall 01 Thrust Goals Attitude Point(a) Point(b) Engine Thrust (b, 200) Warm Up Off Delta_V(direction=b, magnitude=200) Power
Copyright B. Williams J/6.834J, Fall 01 Thrust Goals Attitude Point(a)Point(b)Turn(b,a) Engine Thrust (b, 200) Warm Up Off Delta_V(direction=b, magnitude=200) Power
Copyright B. Williams J/6.834J, Fall 01 Thrust Goals Attitude Point(a)Point(b) Turn(b,a) Engine Thrust (b, 200) Warm Up Off Delta_V(direction=b, magnitude=200) Power
Copyright B. Williams J/6.834J, Fall 01 Thrust Goals Attitude Turn(a,b) Point(a) Point(b)Turn(b,a) Engine Thrust (b, 200) Off Delta_V(direction=b, magnitude=200) Power Warm Up
Copyright B. Williams J/6.834J, Fall 01 Thrust Goals Attitude Turn(a,b) Point(a)Point(b)Turn(b,a) Engine Thrust (b, 200) Off Delta_V(direction=b, magnitude=200) Power Warm Up
Copyright B. Williams J/6.834J, Fall 01 Thrust Goals Attitude Turn(a,b) Point(a)Point(b)Turn(b,a) Engine Thrust (b, 200) Off Delta_V(direction=b, magnitude=200) Power Warm Up Plan Completed!
Copyright B. Williams J/6.834J, Fall 01 Plan Model Fragment Used Thrust Goals Attitude Engine Thrust (b, 200) Delta_V(direction=b, magnitude=200) Power contains
Copyright B. Williams J/6.834J, Fall 01 Thrust Goals Attitude Point(b) Engine Thrust (b, 200) Off Delta_V(direction=b, magnitude=200) Power Warm Up meets met_by contained_by equals Plan Model Fragment Used
Copyright B. Williams J/6.834J, Fall 01 Plans Allow Temporal Flexibility Through Least Committment
Copyright B. Williams J/6.834J, Fall 01 Real-Time Execution Flight H/W Fault Monitors Planning Experts (incl. Navigation) Ground System RAX Manager Diagnosis & Repair Mission Manager ScriptedExecutive Planner/Scheduler Remote Agent RAX_START The executive executes and decomposes the plan
Copyright B. Williams J/6.834J, Fall 01 Executing Temporal Plans [130,170]] [0, 300] Propagate temporal constraints Select enabled events Terminate preceding activities Run next activities
Copyright B. Williams J/6.834J, Fall 01 Propagating Timing Constraints Can Be Costly EXECUTIVE CONTROLLED SYSTEM
Copyright B. Williams J/6.834J, Fall 01 EXECUTIVE CONTROLLED SYSTEM Propagating Timing Constraints Can Be Costly
Copyright B. Williams J/6.834J, Fall 01 EXECUTIVE CONTROLLED SYSTEM Propagating Timing Constraints Can Be Costly
Copyright B. Williams J/6.834J, Fall 01 EXECUTIVE CONTROLLED SYSTEM Propagating Timing Constraints Can Be Costly
Copyright B. Williams J/6.834J, Fall 01 EXECUTIVE CONTROLLED SYSTEM Propagating Timing Constraints Can Be Costly
Copyright B. Williams J/6.834J, Fall 01 EXECUTIVE CONTROLLED SYSTEM Propagating Timing Constraints Can Be Costly
Copyright B. Williams J/6.834J, Fall 01 EXECUTIVE CONTROLLED SYSTEM Solution: Compile Temporal Constraints to an Efficient Network
Copyright B. Williams J/6.834J, Fall 01 EXECUTIVE CONTROLLED SYSTEM Solution: Compile Temporal Constraints to an Efficient Network
Copyright B. Williams J/6.834J, Fall 01 EXECUTIVE CONTROLLED SYSTEM Solution: Compile Temporal Constraints to an Efficient Network
Copyright B. Williams J/6.834J, Fall 01 Real-Time Execution Flight H/W Fault Monitors Planning Experts (incl. Navigation) Ground System RAX Manager Diagnosis & Repair Mission Manager Scripted Executive Planner/Scheduler Remote Agent RAX_START Execution is monitored: Failures are diagnosed and repaired
Copyright B. Williams J/6.834J, Fall 01 Programmers and operators must reason through system-wide interactions to generate codes for: Reconfiguring ModesIdentifying Modes monitoring monitoring tracking goals tracking goals confirming commands confirming commands detecting anomalies detecting anomalies diagnosing faults diagnosing faults reconfiguring hardwarereconfiguring hardware coordinating control policies coordinating control policies recovering from faults recovering from faults avoiding failures avoiding failures Model-based Execution of Activities
Copyright B. Williams J/6.834J, Fall 01 Model-based Execution as Stochastic Optimal Control Controller Plant mode identification mode reconfiguration s’(t) (t) f f s (t) g g o(t) Model Livingstone Goals
Copyright B. Williams J/6.834J, Fall 01 Closed Open Stuck open Stuck closed Open Close Cost 5 Prob.9 Models modes engage physical processes probabilistic automata for dynamics Vlv = closed => Outflow = 0; vlv=open => Outflow = M z + (inflow); vlv=stuck open => Outflow = M z + (inflow); vlv=stuck closed=> Outflow = 0;
Copyright B. Williams J/6.834J, Fall 01 Mode Estimation and Diagnosis Observe “no thrust” Find most likely reachable states consistent with observations.
Copyright B. Williams J/6.834J, Fall 01 Mode Reconfiguration and Repair Goal: Achieve Thrust
Copyright B. Williams J/6.834J, Fall 01 Goal: Achieve Thrust Mode Reconfiguration and Repair
Copyright B. Williams J/6.834J, Fall 01 Goal: Achieve Thrust Mode Reconfiguration and Repair
courtesy JPL Ames-JPL NewMaap: New Millennium Advanced Autonomy Prototype July - November, 1995
courtesy JPL Started: January 1996 Launch: Fall 1998
Copyright B. Williams J/6.834J, Fall 01 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
“With autonomy we declare that no sphere is off limits. We will send our spacecraft to search beyond the horizon, accepting that we cannot directly control them, and relying on them to tell the tale.” Bob Rasmussen Architect JPL Mission Data System