Vehicle Motion Control Based On Optimization With Semi-active Suspension

In the past decades,suspension design has been widely studied,which greatly improves the ride comfort,handling and safety of road vehicles.The semi-active suspension can adjust the mechanical properties of the automobile suspension according to the needs.At the same time,it has the advantages of simple structure and low cost,and has a wide application prospect.By controlling the semi-active suspension,the vibration transmission characteristics of the suspension can be changed,the tire load can be adjusted,and the roll motion of the spring mass can be affected,so as to optimize the driving state of the vehicle.In this paper,the influence of semi-active suspension on vehicle driving state is studied,and the optimal control algorithm is designed for the comfort,safety and yaw tracking performance in the process of vehicle steering.The simulation results show that,the algorithm can reduce the discomfort brought by vertical vibration and roll acceleration to human body,and improve the ride comfort when the car turns at low speed;reduce the overshoot of yaw rate and improve the yaw tracking performance when the car turns at high speed;reduce the lateral load transfer rate and improve the safety of the car when facing the risk of rollover.The main research content of this paper focuses on three aspects.First of all,the coupling dynamic model of vehicles roll and yaw is established,and the off-line identification method of model parameters is given.The online estimation algorithm used to correct the parameters related to the possible change of spring mass is given,and the influence of sensor noise on the algorithm is analyzed to improve the accuracy of the model.Secondly,this paper analyzes the factors that affect the comfort of the vehicle in the process of turning on the uneven road,including the vertical vibration acceleration and the roll acceleration,analyzes the power characteristics of the road excitation that causes the vertical vibration,designs the estimation algorithm of the average power of the road excitation based on the vertical acceleration signal of the spring mass,and designs the filter for the sensor noise.The quantitative description of ride comfort is given.Finally,the MPC controller is designed,and the cost function is given for comfort control target,safety control target and yaw tracking control target respectively,and the boundary condition of cost function switching is explored.Finally,the effectiveness of the control algorithm is verified by simulation.