Research On H_∞ Control Of Semi-active Suspension With Actuator Response Time Delay

Suspension system directly affects the vehicle dynamic performance,such as ride comfort and handling performance.Due to the fixed control parameters of passive suspension,it is difficult to effectively improve the dynamic performance of vehicles under variable driving conditions.Although active suspension can greatly improve the vertical dynamic performance,it is difficult to be popularized in vehicles because of the complexity of system structural and the additional energy consumption.Semi-active suspension with low energy consumption actuator can effectively coordinate the contradiction between energy consumption and dynamic performance of the system,and now it has been highly concerned by experts and scholars.However,the current research on semi-active suspension control ignores the influence of actuator response time delay on the control effect of vehicle dynamics.If the time-delay problem is not considered in the design of the controller,the output of the controller will be inconsistent with the input of the actuator,and the feedback link of the system will lose its function,which will cause the deterioration of the control performance of the system,and even destroy the stability of closed loop system.According to the above shortcomings,this paper takes the semi-active suspension with magnetorheological(MR)damper as the research object and proposes an H_∞control strategy with actuator response time delay,to effectively improve the negative influence of actuator response time delay on the dynamic control effect.The main research contents are as follows:Firstly,a quarter MR semi-active suspension test bench is built,a Bingham model of MR damper was established,and a time-delay MR semi-active suspension model was constructed.Discrete bump road model and continuous random road model were selected as the input of suspension system.Then,a time-delay dependent H_∞robust control method is proposed for the response time delay of MR damper.The stability of semi-active suspension that considering the actuator time delay is analyzed by the Lyapunov method,and critical response time delay of the system is obtained by using cone compensation linearization iterative algorithm and least square method.At the same time,a delay independent H_∞robust control method for comparative analysis is designed.And then,an open loop-control system of MR damper is set up,the actual response time delay of MR damper is tested,and a PI control algorithm is designed to improve the electromagnetic response characteristics of MR damper,so as to reduce the overall response time delay of MR damper and make it smaller than the theoretical critical time delay.Based on this,the gain of the delay dependent H_∞robust controller is determined and the simulation analysis on the bump road and random road is carried out,the simulation results show the effectiveness of the control strategy.Finally,a quarter MR semi-active suspension test bench is built and the dynamic contrast tests under bump road and random road are carried out.The test results are consistent with the simulation results,which validates the validity of the simulation results and the availability of the designed time delay dependent H_∞robust controller in improving the actuator response time delay.Simulation and experimental results indicate that the time delay dependent H_∞robust control strategy can obviously enhance the vehicle dynamic performance under the influence of actuator time delay.;7.29%,6.57%and-2.31%respectively compared with time delay independent H_∞robust control strategy.On the B-class road,the three dynamic performance index are reduced by 5.25%,25.74%and 0.64%respectively compared with passive suspension;3.85%、11.76%and 0.01%respectively compared with time delay independent H_∞robust control strategy.