Prescribed-Performance-Function-Based RISE Control for Electrohydraulic Servo Systems with Disturbance Compensation

Considering that the electrohydraulic servo system has extremely strong nonlinear characteristics, problems such as low initial tracking accuracy and large unmodeled dynamic errors are prominent, leading to easy degradation of control performance. To achieve high-precision position tracking control, this study proposes a robust integral of the sign of the error (RISE) control method with prescribed performance function (PPF) and dual extended state observers (DESOs). Combined with the system dynamic model, DESOs are designed to estimate matched and mismatched uncertainties, respectively. The transformed error signal is obtained based on the prescribed performance function (PPF), while restricting the convergence rate and range of the error. A RISE controller is designed using the backstepping method to suppress both matched and unmatched uncertainties and improve the system robustness. The Lyapunov stability theory proves that the system is semi-globally stable and all signals are bounded. Simulation results show that the proposed control strategy significantly improves the tracking accuracy and error convergence rate of the electrohydraulic servo system, fully verifying the effectiveness of the control strategy.