Sliding mode control of a two-link flexible manipulator for reduced vibration in the presence of unmatched uncertainty and time-varying external disturbance

Accurate positioning of the flexible links is a major challenge for a flexible link manipulator because of the presence of vibration, model uncertainty, and external disturbances. In this work a popular robust controller, i.e., sliding mode controller (SMC) has been developed for joint trajectory tracking and vibration reduction of the two-link flexible manipulator. Due to the payload's variability, which makes the issue even more challenging, the mass of the payload has been treated as uncertain. Proof of the matching condition of the uncertain parameter has also been provided. The system's dynamics have been modelled using the Assumed mode method. Closed-loop stability has been verified using the Lyapunov method. Lyapunov-based controller (LBC) has also been developed for comparison purposes. Payload has been varied to show the effectiveness of the developed controller. The simulation results have exhibited better performance of the SMC over the LBC.