Research On Characteristics And Control Algorithms Of The Semi-active Air Suspension Based On Nonlinear Vibration Model

By researching domestic and foreign achievements about air suspension,and analyzing the conclusion of the comparative analysis of various of semi-active air suspension control strategies,the paper put forward the feasibility of this topic research,purpose,significance,concrete experiment plan.Based on the analysis of the stiffness of air spring,the mathematical model of vertical stiffness of air spring was deduced.Because of the damping adjustable semi-active air suspension model was established,and the one-fourth vehicle model was relatively simple in structure that it was easy to experiment.The simulation model of A,B and C pavement was established by road roughness model,and the performance evaluation index of air suspension was given.On the basis of the analysis of the stiffness characteristics of the air suspension,the 1/4 vehicle of semi-active air suspension mathematical model with damping adjustable was established.In view of the strong nonlinear characteristics of the system,the basic idea was to take a control algorithm of mixed sky-hook damping model as a reference model balancing ride comfort and handling stability,this system was designed with the sliding mode variable structure control method to improve the shortcomings of traditional control theory used in the previous treatment of nonlinear problems.Using the generalized error equation of the sliding mode control,the second-order dynamic performance of the closed-loop system switching surface parameters,choosed the reaching law to cut the chattering phenomenon and mixed real-time equivalent control force was deduced effective tracking of heaven and earth reference model.In order to further reduced the buffeting phenomenon and optimized the suspension performance,it was proposed to combine the fuzzy controller with the synovium control theory to control the approach rate parameter ?.Simulation experiments verified the effect of algorithm about Passive air suspension and SMC on vehicle ride comfort,the results of the simulation showed that the synovium controller acted on nonlinear air suspension with good robustness,stability and tracking,it improved not only the smoothness of the damping adjustable semi-active air suspension,but also improved the control stability and driving safety of the suspension.