robotic space explorers: to boldly go where no ai system has gone before
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Robotic Space Explorers: To Boldly Go Where No AI System Has Gone Before. A Story of Survival 16.412J/6.834J September 19, 2001. Readings and Assignment. Model-based Agents: - PowerPoint PPT PresentationTRANSCRIPT
Robotic Space Explorers:To Boldly Go Where No AI System
Has Gone Before
A Story of Survival
16.412J/6.834J
September 19, 2001
Copyright B. Williams 16.412J/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) 5-47.
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.
Copyright B. Williams 16.412J/6.834J, Fall 01
Outline
• Motivation
• Model-based autonomous systems
• Remote Agent Example
Cassini Maps Titan courtesy JPL
• 7 year cruise
• ~ 150 - 300 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 16.412J/6.834J, Fall 01
Four launches in 7 months
Mars Climate Orbiter: 12/11/98Mars Polar Lander: 1/3/99
Stardust: 2/7/99 QuickSCAT: 6/19/98courtesy of JPL
Copyright B. Williams 16.412J/6.834J, Fall 01
Miscommanded:• Mars Climate Orbiter• Clementine
courtesy of JPL
Spacecraft should be embodied with a survival instinct
Copyright B. Williams 16.412J/6.834J, Fall 01
Vanished:• Mars Polar Lander• Mars Observer
courtesy of JPL
Spacecraft require commonsense…
Copyright B. Williams 16.412J/6.834J, Fall 01
Traditional spacecraft commanding
GS,SITURN,490UA,BOTH,96-355/03:42:00.000; CMD,7GYON, 490UA412A4A,BOTH, 96-355/03:47:00:000, ON; CMD,7MODE, 490UA412A4B,BOTH, 96-355/03:47:02:000, INT; CMD,6SVPM, 490UA412A6A,BOTH, 96-355/03:48:30:000, 2; CMD,7ALRT, 490UA412A4C,BOTH, 96-355/03:50:32:000, 6; CMD,7SAFE, 490UA412A4D,BOTH, 96-355/03:52:00:000, UNSTOW; CMD,6ASSAN,490UA412A6B,BOTH, 96-355/03:56:08:000, GV,153,IMM,231,
GV,153; CMD,7VECT, 490UA412A4E,BOTH, 96-355/03:56:10.000, 0,191.5,6.5,
0.0,0.0,0.0,96-350/00:00:00.000,MVR;
SEB,SCTEST,490UA412A23A,BOTH, 96-355/03:56:12.000, SYS1,NPERR; CMD,7TURN, 490UA412A4F,BOTH, 96-355/03:56:14.000, 1,MVR; MISC,NOTE, 490UA412A99A,, 96-355/04:00:00.000, ,START OF TURN;, CMD,7STAR, 490UA412A406A4A,BOTH 96-355/04:00:02.000, 7,1701,
278.813999,38.74; CMD,7STAR, 490UA412A406A4B,BOTH,96-355/04:00:04.000, 8,350,120.455999,
-39.8612; CMD,7STAR, 490UA412A406A4C,BOTH,96-355/04:00:06.000, 9,875,114.162,
5.341; CMD,7STAR, 490UA412A406A4D,BOTH,96-355/04:00:08.000, 10,159,27.239,
89.028999; CMD,7STAR, 490UA412A406A4E,BOTH,96-355/04:00:10.000, 11,0,0.0,0.0; CMD,7STAR, 490UA412A406A4F,BOTH,96-355/04:00:12.000, 21,0,0.0,0.0;
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 16.412J/6.834J, Fall 01
Reconfiguring for a Failed EngineFuel tankFuel tankOxidizer tankOxidizer tank
Copyright B. Williams 16.412J/6.834J, Fall 01
Reconfiguring for a Failed Engine
Open fourvalves
Fuel tankFuel tankOxidizer tankOxidizer tank
Copyright B. Williams 16.412J/6.834J, Fall 01
Reconfiguring for a Failed Engine
Valve failsstuck closed
Open fourvalves
Fuel tankFuel tankOxidizer tankOxidizer tank
Copyright B. Williams 16.412J/6.834J, Fall 01
Reconfiguring for a Failed Engine
Fire backupengine
Valve failsstuck closed
Open fourvalves
Fuel tankFuel tankOxidizer tankOxidizer tank
Copyright B. Williams 16.412J/6.834J, Fall 01
Challenge: Thinking Through Interactions
Programmers must reason through system-wide interactions to generate codes for:
• command command confirmationconfirmation
• goal trackinggoal tracking• detecting anomaliesdetecting anomalies• isolating faultsisolating faults• diagnosing causesdiagnosing causes
• hardware reconfighardware reconfig• fault recoveryfault recovery• safingsafing• fault avoidancefault avoidance• control control
coordinationcoordination
Equally problematic at mission operations levelEqually problematic at mission operations level
Copyright B. Williams 16.412J/6.834J, Fall 01
Outline
• Motivation
• Model-based autonomous systems
• Remote Agent Example
Copyright B. Williams 16.412J/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 16.412J/6.834J, Fall 01
Example of a Model-based Agent:
• Goal-directed
• First time correct
• projective• reactive
• Commonsense models
• Heavily deductive
Scripts
component models
GoalsGoals
Diagnosis Diagnosis & Repair& Repair
Mission Mission ManagerManager
ScriptedScriptedExecutiveExecutive
Planner/Planner/SchedulerScheduler
Remote AgentRemote Agent
Mission-levelactions &resources
Copyright B. Williams 16.412J/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 16.412J/6.834J, Fall 01
Many problems aren’t so hard
Copyright B. Williams 16.412J/6.834J, Fall 01
GenerateNon-conflicting
Successor
GenerateNon-conflicting
Successor
Candidates withCandidates withIncreasing costIncreasing cost
SATSAT
Explanationfor Conflicts
Explanationfor Conflicts
Developed RISC-like, deductive kernel (OPSAT)
How can general deduction achieve
reactive time scales?
Solutions
Copyright B. Williams 16.412J/6.834J, Fall 01
Transition Systems + Constraints + Probabilities
ClosedClosed
ValveValve
OpenOpen StuckStuckopenopen
StuckStuckclosedclosed
OpenOpen CloseClose
0. 010. 01
0. 010. 01
0.010.01
0.010.01
inflow = outflow = 0
Can model-based agents perform many different types of reasoning from a common model?
VDECU Op_State
On
Engine Op State
Burn_Ignition
BurnBurn_Termination
Shut_down
Off
Early_Prep Wait
Late_Prep
Copyright B. Williams 16.412J/6.834J, Fall 01
Outline
• Motivation
• Model-based autonomous systems
• Remote Agent Example
Copyright B. Williams 16.412J/6.834J, Fall 01
Real-Time Real-Time ExecutionExecution
Real-Time Real-Time ExecutionExecution
Flight Flight H/WH/W
Flight Flight H/WH/WFault Fault
MonitorsMonitorsFault Fault
MonitorsMonitorsPlanning Experts Planning Experts (incl. Navigation)(incl. Navigation)Planning Experts Planning Experts (incl. Navigation)(incl. Navigation)
Remote Agent Architecture
Ground Ground SystemSystemGround Ground SystemSystem
RAX ManagerRAX Manager
Diagnosis Diagnosis & Repair& Repair
Mission Mission ManagerManager
Scripted Scripted ExecutiveExecutive
Planner/Planner/SchedulerScheduler
Remote AgentRemote AgentRAX_STARTRAX_START
Copyright B. Williams 16.412J/6.834J, Fall 01
Real-Time Real-Time ExecutionExecution
Real-Time Real-Time ExecutionExecution
Flight Flight H/WH/W
Flight Flight H/WH/WFault Fault
MonitorsMonitorsFault Fault
MonitorsMonitorsPlanning Experts Planning Experts (incl. Navigation)(incl. Navigation)Planning Experts Planning Experts (incl. Navigation)(incl. Navigation)
Ground Ground SystemSystemGround Ground SystemSystem
RAX ManagerRAX Manager
Diagnosis Diagnosis & Repair& Repair
Mission Mission ManagerManager
ScriptedScriptedExecutiveExecutive
Planner/Planner/SchedulerScheduler
Remote AgentRemote AgentRAX_STARTRAX_START
Executive requests plan
Copyright B. Williams 16.412J/6.834J, Fall 01
Real-Time Real-Time ExecutionExecution
Real-Time Real-Time ExecutionExecution
Flight Flight H/WH/W
Flight Flight H/WH/WFault Fault
MonitorsMonitorsFault Fault
MonitorsMonitorsPlanning Experts Planning Experts (incl. Navigation)(incl. Navigation)Planning Experts Planning Experts (incl. Navigation)(incl. Navigation)
Ground Ground SystemSystemGround Ground SystemSystem
RAX ManagerRAX Manager
Diagnosis Diagnosis & Repair& Repair
Mission Mission ManagerManager
Scripted Scripted ExecutiveExecutive
Planner/Planner/SchedulerScheduler
Remote AgentRemote AgentRAX_STARTRAX_START
Mission manager establishes goals, planner generates plan
Copyright B. Williams 16.412J/6.834J, Fall 01
Real-Time Real-Time ExecutionExecution
Real-Time Real-Time ExecutionExecution
Flight Flight H/WH/W
Flight Flight H/WH/WFault Fault
MonitorsMonitorsFault Fault
MonitorsMonitorsPlanning Experts Planning Experts (incl. Navigation)(incl. Navigation)Planning Experts Planning Experts (incl. Navigation)(incl. Navigation)
Ground Ground SystemSystemGround Ground SystemSystem
RAX ManagerRAX Manager
Diagnosis Diagnosis & Repair& Repair
Mission Mission ManagerManager
ScriptedScriptedExecutiveExecutive
Planner/Planner/SchedulerScheduler
Remote AgentRemote AgentRAX_STARTRAX_START
Executive executes plan
Copyright B. Williams 16.412J/6.834J, Fall 01
Real-Time Real-Time ExecutionExecution
Real-Time Real-Time ExecutionExecution
Flight Flight H/WH/W
Flight Flight H/WH/WFault Fault
MonitorsMonitorsFault Fault
MonitorsMonitorsPlanning Experts Planning Experts (incl. Navigation)(incl. Navigation)Planning Experts Planning Experts (incl. Navigation)(incl. Navigation)
Ground Ground SystemSystemGround Ground SystemSystem
RAX ManagerRAX Manager
Diagnosis Diagnosis & Repair& Repair
Mission Mission ManagerManager
Scripted Scripted ExecutiveExecutive
Planner/Planner/SchedulerScheduler
Remote AgentRemote AgentRAX_STARTRAX_START
Diagnosis system monitors and repairs
courtesy JPL
Walk Through of Cassini Saturn Orbital Insertion
Copyright B. Williams 16.412J/6.834J, Fall 01
Real-Time Real-Time ExecutionExecution
Real-Time Real-Time ExecutionExecution
Flight Flight H/WH/W
Flight Flight H/WH/WFault Fault
MonitorsMonitorsFault Fault
MonitorsMonitorsPlanning Experts Planning Experts (incl. Navigation)(incl. Navigation)Planning Experts Planning Experts (incl. Navigation)(incl. Navigation)
Ground Ground SystemSystemGround Ground SystemSystem
RAX ManagerRAX Manager
Diagnosis Diagnosis & Repair& Repair
Mission Mission ManagerManager
Scripted Scripted ExecutiveExecutive
Planner/Planner/SchedulerScheduler
Remote AgentRemote AgentRAX_STARTRAX_START
Plan for Next Time Horizon
Copyright B. Williams 16.412J/6.834J, Fall 01
Thrust Goals
Attitude
Engine
Power
Copyright B. Williams 16.412J/6.834J, Fall 01
Thrust Goals
Attitude Point(a)
Engine Off
Off
Delta_V(direction=b, magnitude=200)
Power
Mission Manager Sets Goals over Horizon
Copyright B. Williams 16.412J/6.834J, Fall 01
Thrust Goals
Attitude Point(a)
Engine Off
Off
Delta_V(direction=b, magnitude=200)
Power
Planner StartsPlanner Starts
Copyright B. Williams 16.412J/6.834J, Fall 01
Thrust Goals
Attitude Point(a)
Engine Thrust (b, 200) Off
Off
Delta_V(direction=b, magnitude=200)
Power
Copyright B. Williams 16.412J/6.834J, Fall 01
Thrust Goals
Attitude Point(a)
Engine
Delta_V(direction=b, magnitude=200)
Power
Thrust (b, 200) Off
Off
Copyright B. Williams 16.412J/6.834J, Fall 01
Thrust Goals
Attitude Point(a)
Engine
Delta_V(direction=b, magnitude=200)
Power
Thrust (b, 200) Off
Off
Copyright B. Williams 16.412J/6.834J, Fall 01
Thrust Goals
Attitude Point(a)
Engine
Delta_V(direction=b, magnitude=200)
Power
Off
Off Thrust (b, 200)
Copyright B. Williams 16.412J/6.834J, Fall 01
Point(b)
Thrust Goals
Attitude Point(a)
Engine Off
Delta_V(direction=b, magnitude=200)
Power
Thrust (b, 200) Off
Copyright B. Williams 16.412J/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 16.412J/6.834J, Fall 01
Thrust Goals
Attitude Point(a) Point(b)
Engine Thrust (b, 200)Warm Up Off
Off
Delta_V(direction=b, magnitude=200)
Power
Copyright B. Williams 16.412J/6.834J, Fall 01
Thrust Goals
Attitude Point(a) Point(b) Turn(b,a)
Engine Thrust (b, 200)Warm Up Off
Off
Delta_V(direction=b, magnitude=200)
Power
Copyright B. Williams 16.412J/6.834J, Fall 01
Thrust Goals
Attitude Point(a) Point(b) Turn(b,a)
Engine Thrust (b, 200)Warm Up Off
Off
Delta_V(direction=b, magnitude=200)
Power
Copyright B. Williams 16.412J/6.834J, Fall 01
Thrust Goals
Attitude Turn(a,b)Point(a) Point(b) Turn(b,a)
Engine Thrust (b, 200) Off
Off
Delta_V(direction=b, magnitude=200)
Power
Warm Up
Copyright B. Williams 16.412J/6.834J, Fall 01
Thrust Goals
Attitude Turn(a,b)Point(a) Point(b) Turn(b,a)
Engine Thrust (b, 200) Off
Off
Delta_V(direction=b, magnitude=200)
Power
Warm Up
Copyright B. Williams 16.412J/6.834J, Fall 01
Thrust Goals
Attitude Turn(a,b)Point(a) Point(b) Turn(b,a)
Engine Thrust (b, 200) Off
Off
Delta_V(direction=b, magnitude=200)
Power
Warm Up
Plan Completed!Plan Completed!
Copyright B. Williams 16.412J/6.834J, Fall 01
Plan Model Fragment UsedPlan Model Fragment Used
Thrust Goals
Attitude
Engine Thrust (b, 200)
Delta_V(direction=b, magnitude=200)
Power
contains
Copyright B. Williams 16.412J/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
contained_by
equals
Plan Model Fragment UsedPlan Model Fragment Used
Copyright B. Williams 16.412J/6.834J, Fall 01
Plans Allow Temporal FlexibilityThrough Least Committment
Copyright B. Williams 16.412J/6.834J, Fall 01
Real-Time Real-Time ExecutionExecution
Real-Time Real-Time ExecutionExecution
Flight Flight H/WH/W
Flight Flight H/WH/WFault Fault
MonitorsMonitorsFault Fault
MonitorsMonitorsPlanning Experts Planning Experts (incl. Navigation)(incl. Navigation)Planning Experts Planning Experts (incl. Navigation)(incl. Navigation)
Ground Ground SystemSystemGround Ground SystemSystem
RAX ManagerRAX Manager
Diagnosis Diagnosis & Repair& Repair
Mission Mission ManagerManager
ScriptedScriptedExecutiveExecutive
Planner/Planner/SchedulerScheduler
Remote AgentRemote AgentRAX_STARTRAX_START
The executive executes and decomposes the plan
Copyright B. Williams 16.412J/6.834J, Fall 01
Executing Temporal Plans
[130,170]]
<0, 0>
[0, 300]
• Propagate temporal constraints• Select enabled events• Terminate preceding activities• Run next activities
Copyright B. Williams 16.412J/6.834J, Fall 01
Propagating Timing Constraints Can Be Costly
EXECUTIVE
CONTROLLED SYSTEM
Copyright B. Williams 16.412J/6.834J, Fall 01
EXECUTIVE
CONTROLLED SYSTEM
Propagating Timing Constraints Can Be Costly
Copyright B. Williams 16.412J/6.834J, Fall 01
EXECUTIVE
CONTROLLED SYSTEM
Propagating Timing Constraints Can Be Costly
Copyright B. Williams 16.412J/6.834J, Fall 01
EXECUTIVE
CONTROLLED SYSTEM
Propagating Timing Constraints Can Be Costly
Copyright B. Williams 16.412J/6.834J, Fall 01
EXECUTIVE
CONTROLLED SYSTEM
Propagating Timing Constraints Can Be Costly
Copyright B. Williams 16.412J/6.834J, Fall 01
EXECUTIVE
CONTROLLED SYSTEM
Propagating Timing Constraints Can Be Costly
Copyright B. Williams 16.412J/6.834J, Fall 01
EXECUTIVE
CONTROLLED SYSTEM
Solution: Compile Temporal Constraints to an Efficient Network
Copyright B. Williams 16.412J/6.834J, Fall 01
EXECUTIVE
CONTROLLED SYSTEM
Solution: Compile Temporal Constraints to an Efficient Network
Copyright B. Williams 16.412J/6.834J, Fall 01
EXECUTIVE
CONTROLLED SYSTEM
Solution: Compile Temporal Constraints to an Efficient Network
Copyright B. Williams 16.412J/6.834J, Fall 01
Real-Time Real-Time ExecutionExecution
Real-Time Real-Time ExecutionExecution
Flight Flight H/WH/W
Flight Flight H/WH/WFault Fault
MonitorsMonitorsFault Fault
MonitorsMonitorsPlanning Experts Planning Experts (incl. Navigation)(incl. Navigation)Planning Experts Planning Experts (incl. Navigation)(incl. Navigation)
Ground Ground SystemSystemGround Ground SystemSystem
RAX ManagerRAX Manager
Diagnosis Diagnosis & Repair& Repair
Mission Mission ManagerManager
Scripted Scripted ExecutiveExecutive
Planner/Planner/SchedulerScheduler
Remote AgentRemote AgentRAX_STARTRAX_START
Execution is monitored:Failures are diagnosed and repaired
Copyright B. Williams 16.412J/6.834J, Fall 01
Programmers and operators must reason through system-wide interactions to generate codes for:
Reconfiguring ModesIdentifying Modes
• monitoringmonitoring• tracking goalstracking goals• confirming confirming
commandscommands• detecting anomaliesdetecting anomalies• diagnosing faults diagnosing faults
• reconfiguring reconfiguring hardwarehardware
• coordinating control coordinating control policies policies
• recovering from faultsrecovering from faults• avoiding failuresavoiding failures
Model-based Execution of Activities
Copyright B. Williams 16.412J/6.834J, Fall 01
Model-based Execution asStochastic Optimal Control
Controller
Plant
modeidentification
mode reconfiguration
s’(t)
(t)
ffs (t)
gg
o(t)
Model
Livingstone
Goals
Copyright B. Williams 16.412J/6.834J, Fall 01
Closed
Open Stuckopen
Stuckclosed
OpenCloseCost 5
Prob .9
Models• modes engage physical processes• probabilistic automata for dynamics
Vlv = closed => Outflow = 0;
vlv=open => Outflow = Mz
+(inflow);
vlv=stuck open => Outflow = Mz
+(inflow);
vlv=stuck closed=> Outflow = 0;
Copyright B. Williams 16.412J/6.834J, Fall 01
Mode Estimation and Diagnosis
Observe“no thrust”
Find most likely reachable states consistent with observations.
Copyright B. Williams 16.412J/6.834J, Fall 01
Mode Reconfiguration and RepairGoal: Achieve Thrust
Copyright B. Williams 16.412J/6.834J, Fall 01
Goal: Achieve Thrust
Mode Reconfiguration and Repair
Copyright B. Williams 16.412J/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 1996Launch: Fall 1998
Copyright B. Williams 16.412J/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 ArchitectJPL MissionData System