Prescribed performance-based adaptive dynamic surface control for pump-controlled hydraulic systems with matched and mismatched disturbances

Uncertainties, including parametric and unstructured uncertainty, are the main obstacles for hydraulic systems to achieve high precision control. This paper investigates the asymptotic tracking problem of a pump-controlled hydraulic system subject to parametric uncertainties and matched and mismatched time-varying disturbances. First, a predefined performance function is introduced into the controller design to guarantee transient and final tracking accuracy. Then, a continuous differentiable friction model is utilized for feedforward compensation, reducing the designed conservativeness and improving the tracking performance. Moreover, robust terms suppress mismatched and matched disturbances and guarantee asymptotic stability. Adaptive dynamic surface control (ADSC) with nonlinear filters is adopted to reduce the burden of online calculation and improve control accuracy. As a result, a prescribed performance-based adaptive dynamic surface controller is proposed to achieve asymptotic tracking of a pump-controlled hydraulic system. The proposed control strategy is numerically verified and experimentally validated.