The Research On Time Delay Control Of Active Suspension Of Vehicle With Electro-hydrostatic Actuator

Time delay inevitably exists because of signal acquisition and transmission and actuator response for active suspension with electro-hydrostatic actuator(EHA),which causes the active force generated by actuator and the suspension real time status are not synchronized,seriously affect the control effect of the active suspension.This paper mainly considers the time delay of the electro-hydrostatic actuator,and then controls the time delay of the active suspension.Based on bench test,the force model of the actuator is fitted,and the dynamic mathematical model is fitted by the test data,and the time delay expression consist the pure time delay and first order inertia by the dynamic mathematical model,which is also the time delay expression of the active suspension control system,the time-varying delay characteristics of the active suspension are obtained.An internal model controller based on the dynamic mathematical model of actuator is designed.By the Taylor series first order expansion for the internal model controller,the PID controller is obtained and the controller parameters are set,and the time delay of the actuator is controlled.Based on the traditional Smith predicting compensation control,which can not compensate the time-varying delay,an approved Smith predicting compensation controller is designed,which can track the deviation of the suspension compensation model caused by the time delay variation.The analysis of the stability of the approved predicting compensation controller are derived.The internal model-Smith compound time delay control method is obtained by combining the internal model control and the Smith predicting compensation control.The dynamic performance of the active suspension under the internal model PID control,approved Smith predicting compensation control and internal model-Smith compound time delay control are simulated.The bench tests for time delay control of the active suspension are canried out.The simulation results show that the dynamic performance of the active suspension are improved under the internal model PID control,the internal model-Smith compound time delay control and the improved Smith predicting compensation control,and the improved Smith predicting compensation control has the best effect,the internal model PID control is easy to implement,and the active suspension system has high control precision.The internal model PID control is used as the time delay control method of the active suspension,the test results show that under the random road input with driving on a Class C road at 40km/h and sinusoidal road input with the amplitude of 10mm and the frequency is 3Hz,the root mean square value of the mass acceleration of the suspension are reduced by 10.1%and 13.8%respectively,which verifies the effectiveness of the time delay control method.