Time Delay Stability Analysis And Control Research Of Active Suspension With Electro-hydrostatic Actuator

Active suspension has good vibration damping performance,accord with the requirement of today’s people on car comfort,security,and so active suspension in recent years become a focus in the study of the automobile suspension.However,the operation of sensors,controllers and actuators will produce time delays in the working process of active suspension,which causes the main power to lag behind the real-time motion state of suspension,thus reducing the control result of suspension.In this paper,based on the research of vehicle electro-hydrostatic self-powered active suspension supported(51775426),the generation of time delay of EHA active suspension mainly comes from the electro-hydrostatic Actuator.In this paper,the time-delay stability of electro-hydrostatic actuator is analyzed and the time-delay control is studied.Based on the analysis of the structure and working principle of the electro-hydrostatic active suspension,the dynamic model of the electro-hydrostatic active suspension with time delay was established.Based on the theory of delay differential equation,the relationship between controllable damping and critical delay is obtained,and the impact of critical delay on the dynamic characteristics of suspension system is analyzed.Taking the optimal delay feedback coefficient and delay obtained by genetic algorithm as the compensation reference,the adaptive Smith feedback time-delay control was used to compensate the time-delay main force,and the dynamic characteristics of the suspension under the adaptive Smith feedback time-delay control strategy were contrasted and simulated in MATLAB/Simulink environment.On the basis of the two-column shaking table and data acquisition system,the test prototype,the controller and driver required for vibration test were made,and the time delay control test of electro-hydrostatic active suspension were carried out to verify the effectiveness of the adaptive Smith feedback time-delay control strategy..The consequence prove that dynamical feature of the suspension are enhanced under the adaptive Smith feedback time-delay control,and the influence of time-delay on the electro-hydrostatic active suspension is effectively reduced.In the time-domain analysis,the adaptive Smith feedback time-delay control reduces the sprung mass acceleration by 18.26%,the suspension dynamic deflection by 20.83%,and the tire dynamic load by 9.4%compared with the uncontrolled control.Compared with the traditional outer loop LQG control,the dynamic performance of the suspension is improved more greatly.In frequency domain analysis,adaptive Smith feedback delay control compared to not control within 4～12.5Hz frequency scope sprung mass acceleration power spectrum density decreases by 11.16%,suspension dynamic deflection power spectral density of root mean square value decreases by 16.21%,the tyre dynamic load power spectral density of root mean square value decreases by 6.04%,compared to traditional outer ring LQG control scheme in the frequency domain response and improve more smaller,the overall trend is more stable,and the peak and delay control bench test results are basically identical.