A real-time trajectory planner and end-effector collision avoidance control system for a robotic arm

Abstract

Describes the design of a real-time trajectory planner, for a robotic manipulator arm, which generates cartesian straight line motions. The design of the trajectory planner facilitates the incorporation of a collision avoidance control system to allow the end-effector to avoid unknown obstacles in the workspace, based on on-line proximity sensor data. The cartesian trajectory, possibly modified by the collision avoidance control system, is then converted into joint coordinates to command the servo-control loops. An experimental version of this trajectory planner has been implemented on a PUMA 562, the details of which are described. The proximity sensing capability is provided by incorporating an array of ultrasonic sensors in the region of the end-effector to detect obstacles being approached by the robot. In order to meet the computational demand of the control systems a multi-processor 68020 VME-based system was used, communicating with the PUMA servo-control boards using Unimation's SLAVE link.