Application research for hydraulic servo system based on fractional order proportional derivative and [proportional derivative] controllers

For the hydraulic servo system, the IOPID controller can´t meet the requirement of external load disturbance, cross-interference and stability, this paper proposes a new method of designing a controller known as the FOPD and FO[PD] controller. In order to compare the performance index in transient response between the traditional integer order controller and the fractional order controller, the FOPD controller, FO[PD] controller and integer order PID (IOPID) controllers are described according to the design specifications with the same given parameters. From the frequency response and time domain dynamic simulation in the hydraulic servo system, It is obvious to draw a conclusion that the fractional order controller does better control performance than the integer order controller in robustness and dynamic response characteristics.