Funnel function‐based asymptotic output feedback control of hydraulic systems with prescribed performance

An asymptotic output feedback controller for the hydraulic systems with model uncertainty compensation and prescribed performance is proposed here, where state observers, funnel function and nonlinear adaptive controller are integrated via backstepping technology. Only position signal is available in the process of controller design, the velocity and load pressure are estimated by observers. And, the adaptive control law is carried out to approximate disturbance. Then, a funnel function is introduced to guarantee the prescribed tracking error performance and the potential singularity problem in prescribed performance control is avoided. Furthermore, the whole closed system is proved to be asymptotically stable using Lyapunov method. Comparative experimental results performed on hydraulic systems are studied to illustrate the effectiveness of the proposed controller.