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Fault Detection in Autonomous Assembly by Space Robot Using Semantic Task Model ISTS 2006 - s - 02 Keita Sawayama Dept. of Aeronautics & Astronautics, The University of Tokyo Contents Background Our Approach: Use of Semantic Information System Architecture Simulation Experiment
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Fault Detection in Autonomous Assembly by Space Robot Using Semantic Task Model ISTS 2006 - s - 02 Keita Sawayama Dept. of Aeronautics & Astronautics, The University of Tokyo
Contents • Background • Our Approach: Use of Semantic Information • System Architecture • Simulation Experiment • Conclusions
Future Space System • Sustainable Space System • Orbital Recycle & Reconfiguration • Assembly, Maintenance, Diagnosis Autonomous Space Robots Applications
Autonomous Space Robots • Application to routine work • Ex. Small satellites orbital assembly small satellite • Rule-based control • Conventional, Established control approach
Rule-based approach • Suitable for prescribed task sequences • Reliable execution IF THEN condition command Behavior Rule [move(x,y,z)]
Rule-based approach • Suitable for prescribed task sequences • Reliable execution command 1 command 2 command 3 command 4 command 5 command 6
Rule-based approach • Suitable for prescribed task sequences • Reliable execution command 1 command 2 command 3 command 4 command 5 command 6
Rule-based approach • Suitable for prescribed task sequences • Reliable execution command 1 command 2 command 3 command 4 command 5 command 6
Rule-based approach • Suitable for prescribed task sequences • Reliable execution command 1 command 2 command 3 command 4 command 5 command 6
Rule-based approach • Suitable for prescribed task sequences • Reliable execution command 1 command 2 command 3 command 4 command 5 command 6
Rule-based approach • Suitable for prescribed task sequences • Reliable execution command 1 command 2 command 3 command 4 command 5 command 6
Rule-based approach • Suitable for prescribed task sequences • Reliable execution command 1 command 2 command 3 command 4 command 5 command 6 Misaligned!!
Rule-based approach • Suitable for prescribed task sequences • Reliable execution command 1 command 2 command 3 command 4 command 5 command 6
Rule-based approach • Suitable for prescribed task sequences • Reliable execution command 1 command 2 command 3 command 4 command 5 command 6 STOP! Uncertainties in real world tasks
Rule-based approach • Suitable for prescribed task sequences • Reliable execution How to recover ? command 1 command 2 command 3 command 4 command 5 command 6 STOP! Uncertainties in real world tasks
Problem of Rule-based approach • Not flexible to unexpected situations • Robots need more information for control IF THEN condition command Behavior Rule [move(x,y,z)] • Semantics of the action • Purpose, Relevant objects, • Focused relations, ・・・ Semantic Information Key to Flexibility
Our Approach ~Use of Semantic Information~
Our approach • Use of Semantic Information • Normal operations • Unexpected Situations Rule-based control Inference, Re-planning Use of semantic information
Semantics of the behavior Purpose :“Locate” Object :“The blue block” Target :“Beside the yellow block” Semantic Information behind Command Command “move(0,0,-10)” = Rule-basedBehaviordescription + ・ Behavior understanding ・ Situation recognition Basis forrational inference & planning
Example of Using S.I. Command “move(0,0,-10)” + Semantics of the behavior Purpose : “Locate” Object : “The blue block” Target : “Beside the yellow block” Behavior understanding “Locate the blue block beside the yellow block” Situation Recognition “Under satellite assembly situation”
Plan Representation Robot Plan Semantic Information (Annotation) Commands Similar to “Semantic Web” concept
Control Sequence Normal Mode Command 1 Semantic Information 1 Command 2 Semantic Information 2 Command 3 Semantic Information 3
Control Sequence Normal Mode Command 1 Semantic Information 1 Command 2 Semantic Information 2 Command 3 Semantic Information 3
Control Sequence Normal Mode Command 1 Semantic Information 1 Command 2 Semantic Information 2 Command 3 Semantic Information 3
Control Sequence Normal Mode Command 1 Semantic Information 1 Command 2 Semantic Information 2 Command 3 Semantic Information 3
Control Sequence Error occurs Command 1 Semantic Information 1 Command 2 Semantic Information 2 Command 3 Semantic Information 3
Control Sequence Recovery Mode Cause Inference Sensing Planning Command 1 Semantic Information 1 Sensing Action Command 2 Semantic Information 2 Cause Verification Command 3 Semantic Information 3 Recovery Planning Recovery Action
Control Sequence Recovery Mode Cause Inference Sensing Planning Command 1 Semantic Information 1 Sensing Action Command 2 Semantic Information 2 Cause Verification Command 3 Semantic Information 3 Recovery Planning Recovery Action
Modeling Method in STM Relation About Adding Force Force Adding Force Interferes Reduction of Moving Closer Moving Closer Obstacle Role Force By Obstacle By Obstacle Way N Possible Causes
Modeling Method in STM Relation About Adding Force Force Adding Force Interfering Reduction of Moving Closer Moving Closer Obstacle Role Use of Semantic Task Model By Obstacle By Obstacle Way N Way of Function Achievement
[Scenario 1] [Scenario 2] End Effector Downward Cell Upward Force Force Experiment Scenarios Can the system recognize the different influence of the same force? ⇒ Influence ?? ⇒ Influence ??
The WFAs of “Accelerating moving farther” are ---By pushed by something ---By inertial force The WFAs of “Interfering moving closer” are ---By interfering moving path ---By failure in drive torque ---By mismatch in coordinate system ---By interrupting robot motion Result [Scenario 1] [Scenario 2] Same observation, Different interpretation The system can output different causes. Utilization of semantic information for fault detection and diagnosis
Conclusion • New space robot control architecture • Rule-based + Semantic Information • The system utilizes semantic information for handling unexpected events. • Fault detection and diagnosis scheme • The system can understand the situation and infer the cause of the problem flexibly and rationally. Application