An Adaptive Input Shaping Control Scheme for Vibration Suppression in Slewing Flexible Structures

The application of an input precompensation scheme for vibration suppression in slewing flexible structures, with particular application to flexible-link robotic manipulator systems, is considered. The control from such input shaping schemes corresponds to a feedforward term that convolves in real time the desired reference input with a sequence of impulses and produces a vibration-free output. The robustness of such an algorithm with respect to modal frequency variations is not satisfactory but can be improved by convolving the input with a longer sequence of impulses, the tradeoff being a decrease in the transient response speed. An adaptive precompensation scheme is suggested in this work which can be implemented by combining a frequency domain identification scheme, used to estimate the modal frequencies on-line, with a subsequent scheme for adjusting the spacing between the impulses. The combined adaptive input shaping scheme provides the most rapid slew that results in a vibration-free output; experimental results for a single flexible link are presented to verify the technique.