Abstract: A composite adaptive dynamic surface control method was proposed for high accuracy trajectory tracking of an electro-hydraulic servo system under interval excitation condition. By introducing the first-order command filters to process the virtual control signals during the controller designing process, the complicated calculation of the partial derivatives of the virtual control signals could be avoided. In order to realize the estimation and compensation of the unknown damping coefficient and unknown stiffness coefficient of the hydraulic system, a composite adaptive law was designed, and the stringent persistent excitation condition of the conventional adaptive control method was relaxed. The stability of the closed-loop system was analyzed by using Lyapunov theory, and the comparative simulation results based on MATLAB/Simulink have verified the effectiveness of the proposed control method.

Key words: electro-hydraulic servo system; unknown parameters; trajectory tracking; composite adaptive control; dynamic surface control