Prescribed-Time Output Feedback Control for Nonlinear Systems via the Switched High-Order Sliding Mode

This paper focuses on output feedback prescribed-time control problem of nonlinear system subject to bounded disturbance. Firstly, in order to observe and deal with unmeasurable states and disturbances, the prescribed-time observer and filter are constructed. The prescribed-time state stabilization problem of the original system is translated into how to design the controller to make the state of filter stable in a predetermined time. Then, to overcome the effect of unknown disturbance during the design process, a novel switched prescribed-time high-order sliding mode (HOSM) is constructed. The output feedback prescribed-time control scheme is presented in conjunction with the proposed prescribed-time HOSM to guarantee the prescribed-time stability of system. Finally, the effectiveness of the main result is demonstrated through two numerical simulations, a third order nonlinear system and the single-link robot system.