Finite-Time Output Feedback Control for Flexible-Joint Systems Under Time-Varying Disturbances

The paper studies the trajectory tracking problem of flexible-joint systems under time-varying disturbances. A novel finite-time observer based control methodology is proposed for systems, which is targeted to improve the tracking performance and reduce the effect of the disturbances on the systems. The design mainly consists of a finite-time observer and a finite-time output feedback controller. The finite-time observer is used to estimate unknown time-varying disturbances, higher-order derivatives of the disturbances and unmeasurable states in finite time. The finite-time output feedback controller realizes the closed-loop control in finite-time by using the estimates of the unmeasurable states and unknown time-vary disturbances from the finite-time observer. Compared with the conventional generalized proportional integral observer based control scheme, test results under two different conditions are presented to demonstrate the effectiveness and superiority of the proposed method.