Robust Vibration Suppression in Flexible Payloads Carried by Robot Manipulators Using Digital Filtering of Joint Trajectories

In this paper, a method for suppressing residual vibrations in flexible payloads, carried by robot manipulators, is proposed and experimentally demonstrated. The proposed method is based on the preconditioning of the robot joint trajectories using FIR digital filters. Several classes of FIR filters such as: a) Parks-McClellan, b) Window-based methods (using Hamming, Hanning, Boxcar, Kaiser, Bartlett, Blackman and Chebyshev window), c) Least Squares method and d) Constrained Least Squares method are shown in this work to demonstrate excellent vibration suppression when they are properly designed. Three of the filters (Parks-McClellan, Chebyshev Window-based method and Constrained Least Squares) introduce minimum time delays. In order to ensure maximally robust behavior, the filter stop band is selected to cover all possible variations of the system dynamic parameters. The proposed method does not require modeling of the payload, can be used in a variety of flexible payloads, is independent of the commanded joint trajectories, is simple to implement in practical applications and robust to variations of the system dynamic parameters. In addition, no extra sensors or actuators are needed to perform the vibration suppression.