Prescribed-Time Output-Feedback Tracking Control of a Class of Time-Varying Output-Constrained Systems

In this article, the prescribed-time output-feedback tracking control problem for time-varying output-constrained systems with unknown disturbances is addressed. First, based on the parametric Lyapunov equation (PLE), a novel time-varying state observer is constructed by a time-varying high-gain function. Then, a category of prescribed-time output-constrained functions is defined, and a class of time-varying barrier Lyapunov functions (BLFs) is developed. Based on these, a time-varying high-gain output-feedback tracking control scheme is designed without requiring full state information and disturbance boundary. It is proved that the proposed controller can drive the tracking error of the time-varying output-constrained system to tend to zero in a prescribed time under unknown disturbances. Finally, the prescribed-time tracking control approach is applied to a single-link robot, and several numerical simulations validate the effectiveness of the proposed method.