Hardware-in-the-loop Simulation of Electro-hydraulic Driving Force Servo System

A hydraulic servo system has nonlinearity and uncertain dynamics, so its theoretical mathematical model can´t sufficiently represent the practical system. The identification experiments were carried out in hardware-in-the-loop simulation environment and the identification model was acquired. In order to improve the tracking performance of the force servo system a new nonlinear hybrid controller was developed composed of a classical PID controller and a fuzzy controller based on self-adjusting modifying factor, which was added feedforward compensation. A fuzzy switching mode was employed to avoid the undesirable disturbances caused by the switchover between the two control methods. By simulations and experiments on an electro-hydraulic servo test bench the feasibility of the control scheme was validated by comparison with a PID and a conventional fuzzy control. The research results show that the hybrid PID controller improves stability and rapidity when load rigidity and mass changed, and has good performances in real time applications.