Tracking Error Based On-line Trajectory Time Scaling

Abstract

This paper presents an online time scaling concept for robotic manipulators. The task is to ensure the fastest possible motion along a trajectory with a given geometry in the robot workspace. The other requirement is tracking accuracy. Robots should move not only with high speed but with high precision as well. The speed of the motion cannot be arbitrary fast. It is delimited by the saturation of the actuators and by some other (e.g. security) constraints. Offline time scaling solutions change the speed of the motion without changing its geometry, thus these constraints are not violated. If the exact torque bounds are not known in advance, another method should be used. This work gives an online time scaling algorithm which is based on the tracking error. Simulations demonstrate the usefulness of the algorithm proposed