Improving the robustness in motion planning of flexible systems through structural modification: a case study

This work proposes a technique aimed at improving the suppression of the residual vibration of uncertain flexible systems by the concurrent application of structural modification and of model-based motion planning methods. The novelty of the technique relies on the first stage of the method: a robust structural modification strategy is employed to enhance the robustness of the system natural frequencies to unmeasured parametric deviations. Then, motion planning through the well-known input shaping techniques is employed to suppress the residual vibrations. The proposed method is applied to a numerical test-case: a four degrees of freedom pendulum whose tip-end mass is uncertain, representing a payload that might vary. The results show that increasing the robustness of the natural frequencies is beneficial in improving the performances of motion planning even if large mismatches between the assumed and the actual plant occur.