Research On Control Strategy Of Integrated Chassis System Based On In-Wheel Motor Electric Vehicle

The electric wheel vehicle has advantages of high transmission efficiency and flexible spatial arrangement.It is easy to realize the active chassis system,and has good application prospect.In this paper,the electric wheel vehicle integrated chassis system is taken as the research project.Considering the influence of the change of electric wheel vehicle’s driving mode on vehicle dynamic performance,external disturbance and the coupling relationships among chassis subsystems,the hierarchical control strategy and sliding mode decoupling control strategy based on inverse system of integrated chassis system are studied.The main contents of this paper are as follows:Firstly,considering the coupling relationship between the vertical motion and lateral motion of vehicle and various factors of vehicle driving,the dynamic model of vehicle,differential steering system and active suspension system are established.Considering the characteristics of in-wheel motor,the model of in-wheel motor is established,which lays the foundation for the subsequent hierarchical control and decoupling control research.Secondly,in order to solve the problem of riding comfort and handling stability degradation caused by the increase of unsprung mass,a hierarchical control strategy for the electric wheel vehicle integrated chassis system of differential steering and active suspension is formulated.The fuzzy control algorithm is used in the upper controller to adjust the control weight of the differential steering subsystem and the active suspension subsystem in real time.The linear quadratic regulator algorithm is adopted in the lower controller to decide the additional yaw moment that should be applied to the vehicle.The active suspension system uses the active disturbance rejection algorithm to control the forces of active suspension to suppress the vehicle body vibration and improve the riding comfort.Finally,in order to improve the limitation of hierarchical control on handling stability,considering the external disturbance and mutual interference among each subsystem,a sliding mode decoupling controller of integrated chassis system based on inverse system method is proposed.The existence of the inverse system of the original integrated chassis system is derived through the proof of system invertibility,and the original system is decoupled into three independent subsystems by the inverse system decoupling method.On this basis,a closed-loop controller is designed based on sliding mode control to improve the tracking performance and robustness of vehicle.The results of simulation show that the proposed decoupled controller has excellent decoupling performance,tracking performance and robustness,which improves the dynamic performance of the vehicle.The research of this paper can provide theoretical support for the research of integration and decoupling control of the electric wheel vehicle chassis system.