Extended‐state‐observer‐based prescribed performance output feedback control of nonlinear electrohydraulic servo system

Abstract This paper proposes the prescribed performance feedback controller for a nonlinear electro‐hydraulic system with unknown disturbances. A higher‐order extended state observer is designed to estimate unmeasurable states and compensate for uncertainties. Then, a prescribed performance function is proposed to constrain both the transient and steady‐state behavior of the system. In addition, command filtering with error compensation is incorporated into the design of the backstepping controller to mitigate the explosion of complexity. Finally, the performance of the proposed controller is verified through four simulation examples.