Design and control of a hydraulic composite actuator for vibration simulation

A hydraulic composite actuator is developed for vibration simulation. The hydraulic scheme and control principle are introduced and an open–closed-loop iterative learning control method is proposed for control issue. A special composite cylinder controlled by servo valve and proportional relief valve is designed to generate static force with large amplitude and dynamic force with small amplitude but high frequency. The control subsystem for dynamic force is a zero-type system with very high open-loop gain and uncertainty of parameters; therefore, an open–closed-loop proportional–derivative-type iterative learning control scheme is designed to solve this challenging control issue. A principle prototype of this hydraulic has been developed, and the experiments have been designed for this actuator. Different control methods are experimented for verification and comparison, and experiment results have verified practical applicability of this actuator and the superiority of control scheme.