Disturbance Observer-Based Prescribed-Time Tracking Control of Nonlinear Systems With Non-Vanishing Uncertainties

In this brief, a disturbance observer based prescribed-time tracking control strategy is proposed for a class of high-order nonlinear systems with non-vanishing uncertainties. A finite time function is firstly introduced to facilitate the disturbance observer and controller design. Then, a prescribed-time disturbance observer is constructed to estimate and compensate for the non-vanishing uncertainties, which ensures that the estimation error converges to zero in a prescribed time. Based on the backstepping design framework, the prescribed-time controller is further designed in the form of scaling the tracking error. Theoretical analysis reveals that the proposed controller achieves the excellent prescribed-time convergence of the full state tracking errors, and the convergence time can be explicitly predetermined, independent of the initial conditions. Finally, the validity and superiority of the proposed controller is demonstrated via numerical simulation.