Integration of Representation Into Goal-Driven Behavior-.ppt

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1、Integration of Representation Into Goal-Driven Behavior-Based Robots,By Dr. Maja J. MataricPresented by Andy Klempau,Introduction,Hybrid system separates reactive low level actions from deliberative decision actions. Alternative to Hybrid approach is Behavior-Based system. Behavior-Based system comb

2、ines a reactive subsumption foundation with a decision maker. Toto is a Behavior-Based robot that explores dynamic office environments, identifies landmarks, maps the landmarks, and uses the map for path planning.,Outline,Totos Structure Basic Navigation ( Exploring ) Landmark Detection Mapping Land

3、marks Path Planning,Totos Structure,Cylindrical Robot12 Sonar Sensors4 Bit Compass (16 states),Basic Navigation,Subsumption Architecture Highest priority is Stroll behavior Lowest priority is Correct behavior,Basic Navigation,Stroll : if( min( sonars 1 2 3 4 ) = danger-zone ) if( not stopped ) stop

4、else move backward else move forward,Basic Navigation,Avoid : if( ( sonar 3 or 4 ) = safe-zone ) turn left else if( ( sonar 1 or 2 ) = safe-zone ) turn right,Basic Navigation,Align : if( ( sonar 7 or 8 ) edging-distance ) turn right if( ( sonar 9 or 10 ) edging-distance ) turn left,Basic Navigation,

5、Correct : if( sonar 11 edging-distance ) turn left if( sonar 6 edging-distance ) turn right,Landmark Detection,4 types of landmarks: Right wall (RW); consistent right wall and consistent direction. Left wall (LW); consistent left wall and consistent direction. Corridor (C); consistent left and right

6、 walls and consistent direction. Irregular (I); inconsistent walls and inconsistent direction.How does Toto identify landmarks?,Confidence Counter!,Landmark Detection,After a time interval, sonar and compass readings are taken. Confidence Counter increments when sonar and compass readings are the sa

7、me as last time interval. Predetermined threshold identifies how many time intervals are needed to justify a landmark,Landmark Detection,Mapping Landmarks,After discovered, landmarks are stored in Totos internal map. Landmark nodes store information discovered through sensors and compass (see next s

8、lide). Nodes communicate with neighbors.,Mapping Landmarks,Landmark node has a set whereT is LW, RW, C, I ; qualitative landmark type.C is 0 15 ; averaged compass bearing.L is 1 127 ; rough estimate of landmarks length.P = ( x, y ) -128 = x, y = 127; coarse position estimate.Length is obtained throu

9、gh timer (could be confidence counter). Position is obtained through length and compass.,Mapping Landmarks,Example:,Path Planning,Use the map to go to a goal. This is done by activating one of Totos previously visited landmarks as a goal.,Path Planning,Goal sends signal to neighbor nodes. Eventually

10、, all nodes know where goal is. Greedy algorithm ensures Toto will take shortest path to goal. Toto can go to goal starting from any landmark. Toto can adapt to a changing environment.,Review,ExploresFinds landmarksStores landmarks in mapGoes to goal,Conclusion,Toto explores, maps, plans, and finds

11、goals without Deliberative or Hybrid process. Toto “extends the repertoire of integrated reactive systems to tasks requiring spatial modeling and user interaction.” Toto can adapt to a dynamic environment.,Discussion,Is linear-time path planning reactive? Can a Behavior-Based system do anything a hybrid system can do? How is the open-space behavior triggered?,