Saturated Adaptive Control of an Electrohydraulic Actuator with Parametric Uncertainty and Load Disturbance

In this paper, a saturated adaptive control of an electrohydraulic actuator is proposed to drive the joint motion of a two-degree-of-freedom robotic arm. Due to the largely unknown load disturbance from the driven force/ torque of the robotic arm and the existing control saturation of a servo valve, a Nussbaum function is designed to compromise between the antiwindup control effect and the dynamic response performance of an electrohydraulic system. Then, an adaptive parametric estimation law is designed to estimate the hydraulic parametric uncertainties. The effectiveness of the proposed controller has been demonstrated by comparative experimental study, which indicates that this controller can quickly recover the unsaturated dynamics with satisfactory tracking accuracy under largely unknown load disturbance and parametric uncertainty.