Abstract:In the diaphragm type pneumatic drive system, the pressure compressibility and effects of various external factors, making it a variable highly nonlinear system, which lead in the dynamic behavior of system is not accurate enough, and the conventional PID controller cannot overcome these factors. In order to seek a more effective control strategy, using orthogonal function as a function of substrate approximation method instead of the system dynamic model of unknown function, and design an adaptive sliding mode controller for pneumatic driving system for trajectory control. In the study, we also use the Lyapunov stability law to ensure the stability of the controlled process, and get the update law of the system control parameters. The experimental results show that: using function approximation method based adaptive sliding mode controller, in single cylinder diaphragm type pneumatic drive system had a better control effect, had the strong robustness to external disturbance and parameter uncertainty and had the superiority in variable structure control.