Learning of Sensor-Based Arm Motions while Executing High-Level Descriptions of Tasks

  • Authors:
  • Pedro Martín;José Del R. Millán

  • Affiliations:
  • Department of Computer Science, Universitat Jaume I, 12071 Castellón, Spain. martin@inf.uji.es;Joint Research Centre, European Commission, 21020 Ispra (VA), Italy. jose.millan@jrc.it

  • Venue:
  • Autonomous Robots
  • Year:
  • 1999

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Abstract

Our work focuses on making an autonomous robot manipulatorlearn suitable collision-free motions from local sensory data whileexecuting high-level descriptions of tasks. The robot arm must reacha sequence of targets where it undertakes some manipulation. Therobot manipulator has a sonar sensing skin covering its links toperceive the obstacles in its surroundings. We use reinforcementlearning for that purpose, and the neural controller acquiresappropriate reaction strategies in acceptable time provided it hassome a priori knowledge. This knowledge is specified in two mainways: an appropriate codification of the signals of the neuralcontroller—inputs, outputs and reinforcement—and decompositionof the learning task. The codification facilitates the generalizationcapabilities of the network as it takes advantage of inherentsymmetries and is quite goal-independent. On the other hand,the task of reaching a certain goal position is decomposed intotwo sequential subtasks: negotiate obstacles and move togoal. Experimental results show that the controller achieves a goodperformance incrementally in a reasonable time and exhibits hightolerance to failing sensors.