A cheap output feedback tracking controller with robustness: the RLFJ problem

In this paper, we propose a robust output feedback link position tracking controller for the full-order model used to describe rigid-link flexible-joint (RLFJ) robot manipulators. The method uses a bank of dynamic filters, with the link position tracking error as the input, to generate surrogates for the immeasurable system states. One of these generated filter states is then used in the feedback control strategy. The method is distinguished from previous results by the limited amount of modeling information required, the utilization of only link position measurements, and the overall simplicity of the controller. Even though the approach only requires link position measurements, the controller exhibits good robustness properties while ensuring semi-global uniformly ultimately bounded link position tracking