Adaptive fuzzy sliding mode control for missile electro-hydraulic servo mechanism

The position tracking control of a missile electrohydraulic servo mechanism is studied. Since the dynamics of the system are highly nonlinear and have large extent of model uncertainties, such as big changes in load and parameters, a design method of adaptive fuzzy sliding mode control is presented. The adaptive fuzzy controller is introduced to approach the equivalent control of sliding mode control, which solve the problem that the equivalent control can not be obtained accurately because of the uncertain parameter and external disturbances of the system, so the controller can be designed without accurate model. Then the adaptive law is derived based on Lyapunov method. The nonlinear controller, which guarantees the stability of control system, is also developed. In order to attenuate the high frequency chattering, two constructed heuristic control rules are employed to smooth the control law based on the concepts of sliding mode control. The validity of the approach is verified by Matlab. Simulation results show that the control approach can decrease the tracking error, enhance the systempsilas robustness and attenuate the high frequency chattering in the control signal.