Design of Cascade Observers for Robot Angular Link Velocity

A new observer, namely a cascade observer, for a general class of nonlinear SISO systems was presented by the authors [1]. Inspired by but different from a highgain observer, the cascade observer features a cascade structure and adaptive observer gains. In doing so the cascade observer attempts to overcome some of the typical problems that may pose to a high-gain observer. Based on the cascade observer, the estimation problem of the angular link velocity is presented in this paper. As in the case of a highgain observer, the cascade observer structure is simple and universal in the sense that it is independent of the system dynamics and parameters. It is shown that the proposed cascade observer is applicable to robotic state estimation using only joint position measurements effectively.