Abstract: A robust adaptive control strategy was proposed to improve the robustness and enhance the position tracking accuracy of valve controlled asymmetric cylinder position system with unknown nonlinearities and uncertain parameters. Dynamic surface control technique was introduced to avoid the inherent “explosion of complexity” problem of the traditional back stepping method, and the design process of the nonlinear controller could be simplified. By combining a discontinuous projection operator, the unknown parameters could be estimated effectively. The stability of the closed loop system was analyzed by using Lyapunov stability theory, and the simulation results have verified the effectiveness of the proposed control method.

Key words: adaptive robust control, valve controlled asymmetric cylinder, unknown nonlinearities, unknown parameters, dynamic surface control technique