Sliding mode tracking control of a very lightweight single-link flexible robot robust to payload changes and motor friction

A sliding mode control design methodology is applied to solve the position tracking problem of an uncertain very lightweight single-link flexible robot arm. Throughout this work we seek a control scheme robust with regards to payload and actuator friction changes, without the establishment of any bounding limits on these parameter variations. Based on the decomposition of the robot dynamics into the motor and flexible link submodels, two nested control loops are proposed, each one of these controlled by an independent sliding mode controller. By carrying on this model decomposition, both motor friction and payload changes become matched uncertainties in their respective models, allowing for their effective rejection using these sliding controllers. Simulations and experimental results are shown to demonstrate the performance of the control system proposed.