Robust control for high-accuracy hydraulic simulator

A robust compound control structure is presented for hydraulic simulator, which suffers from severe time-varying uncertainty and external disturbance, and whose performance requirement, such as high-accuracy tracking control, becomes higher and higher. The proposed control structure consists of a robust inner loop compensator, an outer loop feedback controller and a command signal feedforward compensator. The robust inner loop compensator is used for restraining the influence of external disturbance and plant time-varying uncertainty on control system. The feedback controller guarantees the overall performance of closed-loop system. The feedforward compensator realizes the compensation for dynamic time lag of system in order to make the hydraulic simulator excellently track the reference signal. Taking the inner gimbal of a certain type of hydraulic simulator as example, the design process is presented according to the proposed control strategy, and then, a series of experiments, such as step response, ultra-low tracking and sine response experiments, are carried out. Experimental results demonstrate that the proposed control strategy for hydraulic simulator is valid and feasible.