Direct Drive Electro-hydraulic Servo Control System Design with Self-Tuning Fuzzy PID Controller

According to the nonlinear and time-varying uncertainty characteristics of direct drive electrohydraulic servo control system, a self-tuning fuzzy PID control method with speed change integral and differential ahead optimizing operator is put forward by combining fuzzy inference and traditional PID control in this paper. The rule of fuzzy logic is designed, the membership function of the fuzzy subsets is determined and lookup table method is used to correcte the PID parameters in real-time. Finally the simulation is conducted with the typical input signal, such as tracking step, sine etc. The simulation results show that, the self-tuning fuzzy PID control system can effectively improve the dynamic characteristic when the system is out of the range of the operating point compared with the traditional PID control system, there is obvious improvement in the indexes of rapidity, stability and accuracy, and fuzzy selftuning PID Control is more robust, and more suitable for direct drive electro-hydraulic servo system.