Nonlinear robust control of flexible-link manipulator with fuzzy compensator: Experimental results

This paper presents a methodology for trajectory control of single-link lightweight flexible manipulators. The objective is to control the trajectory of the tip position of the flexible-link manipulator in the presence of joint friction and output disturbances. Robust nonlinear approach is applied to guarantee system stability and to alleviate the degrading effects of uncertainties and nonlinearities presented in the dynamics of the system. Output redefinition is used to cancel the effects of the internal instability of the zero dynamic of the flexible-link. A drawback of this method, however, is that the controller is designed to track a new output trajectory. In fact, the difference between the tip position and new defined output could be significant and affects the tracking performance. To overcome this problem, a fuzzy compensator is employed. Simulation study and experimental results are presented to illustrate the performance of the proposed composite control strategy.