A digital implementation of the acceleration feedback control law on a PUMA 560 manipulator

A design procedure that shows how the acceleration feedback control law, with the frequency weighting compensator, can be implemented digitally, requiring only position data as input, is presented. The design procedure was applied to the shoulder joint of a PUMA 560 manipulator. It was demonstrated that the major limitations on the performance of this control law are due to the design of the robot itself. These limitations arise from friction in the mechanical transmission, structural resonances, and low actuator saturation thresholds in the PUMA 560. It is shown that the acceleration feedback control law can achieve improvement in tracking while using a slightly less energetic control action, in comparison to a similarly tuned proportional plus derivative controller. Tuning of the modified acceleration feedback control law entails selecting the appropriate saturation limits for clipping the numerical differentiators. High frequency uncertainty constrains how high these saturation limits may be set