<title>Sensor-based whole-arm obstacle avoidance for kinematically redundant robots</title>

Abstract

This paper discusses the technical feasibility of proximity sensor based control for kinematically redundant robot arm manipulators. In contrast to model-based approaches, sensor based control techniques require no a priori knowledge of the operational environment. The method described in this paper uses infrared proximity sensors located about the periphery of a three degree of freedom planar mechanism to provide real time knowledge of the environment near the manipulator. The control algorithm produces a collision-free path around detected obstacles based on this information, while allowing the end effector to reach the desired goal position. A fully functional collision avoidance system for a redundant planar manipulator was constructed and tested. The testbed incorporated a SCARA-type robot manipulator with a sensor 'skin' comprised of 49 infrared sensor pairs about its periphery. A standard desktop computer served as the process controller. This work is currently being extended to redundant spatial manipulators under a NASA Phase II SBIR research grant. Also, related work into proximity sensor technology and distributed sensor data processing has recently been completed, in which the performance characteristics of infrared, capacitive, and ultrasonic sensing devices were measured. A distributed processing electronics system and supporting communications protocol was developed and successfully tested.