Autonomous Parallel Robot Control: Combining High Tracking Accuracy and Short Cycle Times

I.T. Pietsch, O. Becker, M. Krefft, C. Bier, and J. Hesselbach (Germany)

Keywords

Parallel Robots, Tajectory Planning, Adaptive Control

Abstract

During the past years parallel robots proved to be an ef ficient and suitable supplement to serial robots. Unfortu nately, the promising possibilities of parallel robots often cannot yield profit because their dynamic potential is still not fully exploited. Due to the fact that the payload/ robot mass ratio of parallel structures is significantly higher com pared to their serial counterparts, the influence of pay load changes on the dynamic robot behavior is not negli gible. A modified adaptive control concept, which adapts autonomously to changing dynamic parameters as vary ing payload guarantees high tracking accuracy as well as accurate estimates of changing dynamic parameters. A new adaptive time-optimal trajectory planning algorithm is used to shorten the cycle times considering admissible drive forces, limited path and drive velocites, jerk limita tions and varying payload. Combining the adaptive control scheme and the adaptive, time-optimal trajectory planning algorithm with an online trajectory adaption mechanism, a control concept is realized, which autonomously adapts to changing dynamic robot behavior. The performance of this new approach is demonstrated by means of the plane high-speed parallel robot PORTYS.

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