Research On Double Sliding Mode Switching Control Of EHA Active Suspension

With the increase of service life or the change of working environment,the active suspension with electro-hydraulic actuator(EHA)actuator will have a failure phenomenon that the actual active force is less than the required one,which weakens the suppression effect of active suspension system on ground excitation,and reduces the comfort and handling stability of drivers and passengers.In this paper,on the basis of improving the performance of the active suspension and considering the failure of the actuator,a double sliding mode switching control strategy is designed to study the control of the active suspension.Based on the analysis of the structure and working principle of the active suspension,the dynamic model and failure model of the active suspension are established.A double sliding mode control strategy including active mode and failure mode is proposed:in active mode,a double sliding mode inner and outer loop control is designed,including outer loop sliding mode control based on model reference and motor inner loop sliding mode control;Kalman filter state estimation algorithm is used to estimate the value of various state variables of suspension system and judge whether the suspension actuator is invalid In the failure mode of the actuator after failure,the failure factor of the actuator is calculated by Kalman filter estimation algorithm to compensate the output active force,and a compound switching condition is proposed to improve the switching stability of the control strategy in the mode switching.In the environment of MATLAB/Simulink,the dynamic characteristics and output active force characteristics of the electro-static hydraulic active suspension when the above control strategy is adopted are simulated and analyzed.Finally,the bench test system is trial manufactured in the laboratory environment.Based on the two column vibration table and data acquisition system,the test prototype,the controller and driver required for the vibration test are made and carried out the suspension active control test and failure compensation test are acquisition system,the test prototype,the controller and driver required for the vibration test are made and carried out the suspension active control test and failure compensation test are carried out.The simulation results show that in the active mode,the double sliding mode inner and outer loop control strategy can significantly reduce the output force ripple of the actuator of the electro-static hydraulic active suspension;in the failure mode,the mode can be switched to restore the performance of the electro-static hydraulic active suspension to the level close to the normal suspension.The test results show that the acceleration of sprung mass is 37.86%and 31.07%lower than that of passive suspension on different roads in active mode,and 26.7%lower than that of suspension actuator with failure factor of 0.6 in failure mode,which improves the deterioration of vehicle dynamic characteristics caused by actuator failure.