Research On Semi-active Control Method Of Automotive Electronic Air Suspension

Comfort and maneuverability have always been the two core standards for measuring the quality of automobiles.How to achieve the balance between the two features has always plagued car designers.The emergence of the air suspension system can realize the combined control of the suspension damping and the height of the vehicle,not only solving the problems of ride comfort such as body vibration and suspension deflection,but also improving driving safety and handling stability.In recent years,electronically controlled air suspension technology has broad application prospects in the design of automotive suspension systems.Researching safe and effective intelligent control methods is of great significance in promoting the application of air suspension systems.In this paper,when studying the semi-active control method of the electronically controlled air suspension system,the design of the suspension damping controller and the vehicle height controller is the main task.In the process of designing the damping controller,the dynamic model of the air suspension system and the semi-active damping suspension system is first established,the body movement error equation of the suspension system is solved,and the damping controller is designed using the sliding mode variable structure system control method.Aiming at the chattering problem of control signal generated by the switching control part of the ordinary sliding mode variable structure control,RBF(Radial basis function)neural network is used to replace its switching control part to realize the continuous stability control of suspension damping.In the process of designing the vehicle height controller,a dynamic model of air suspension with vehicle height adjustment is established.Considering the existence of time lag,overcharge,over-discharge,and oscillation of the air spring charging and deflation system,a double closed-loop control strategy is proposed..The outer ring adopts the sliding mode variable structure control method to track the vehicle height error to calculate the demand and control quantity of the charging and ventilating system;the inner ring adopts the neural network PID algorithm to adjust the control signal of the highly executed system.In order to avoid the influence of the coupling of control parameters in the damping and vehicle height adjustment on the system modeling and control strategy,the Stateflow modeling method is used to graphically model the switching control of the two functional modes,and is set to conform to various operating mode modes,by setting the logic switching rules in accordance with various operating modes,the two controllers can work together in a stable manner.Finally,a control system model of suspension damping and vehicle height adjustment was established in Matlab/Simulink and simulation experiments were conducted.Stateflow control model was used to perform state transfer simulation experiments for the set function mode switching rules.From the simulation results,we can see that in the damping control,the performance indicators of the suspension system are effectively improved in both time domain and frequency domain analysis,the vehicle height control system improves the control accuracy while ensuring system reliability,the Stateflow switching control system achieves coordinated and stable switching among various functional modes,effectively solves the coupling of state parameters between control parts,it is verified that the designed control method can fully exert the function of the air suspension system and effectively improve the comprehensive performance of the vehicle.