The Integrated Control Of Active Suspension And Drive Force Distribution Based On 4 In-Wheel Motor Driven Electric Vehicle

In recent years, as environmental deterioration and energy shortage problem are more and more attention, the in-wheel motor driven electric vehicle has become a hot research topic at domestic and overseas because of its independent drive system.The installation of the in-wheel motors greatly increases the vehicle's unsprung mass, has affected the tire of grounding resistance at the same time increasing the moment of inertia of the suspension, in-wheel motors are also vulnerable to suffer greater stroke, the redesign of suspension structure is particularly important, active suspension provides a balance of vehicle ride comfort and handling stability of the solution. Meanwhile in order to meet the requirements of the automobile industry rapid development, based on the single chassis control system has been unable to satisfy the performance requirements of modern vehicles, we take advantage of in-wheel motor driven vehicle to present an integrated control for improving the yaw stability, roll characteristics of vehicle and protecting in-wheel motors using active suspension and drive force distribution. Detailed research contents of this paper is described as follow:(1)Based on the characteristics of the in-wheel motor driven electric vehicle to establish the four degrees of freedom vehicle model to reflect the vehicle's roll motion and vertical motion, to establish two degrees of freedom of the bicycle model to reflect of horizontal pendulum movement and lateral movement. Through H.B.P acejka tire model, the lateral force of the tire will be connected to the vertical force of the tire;(2)Present simulations of the vehicle model in the commercial software Carsim under Fishhook steering and sudden road excitation, comparison of unsprung mass and sprung mass influence on the dynamic parameters of the vehicle, to verify the influence of installation of the in-wheel motors on the vehicle handling stability;(3)Design a controller of active suspension using linear optimal control to improve the vehicle dynamic response, reducing the displacement of unsprung mass and center of spung mass. Meanwhile, we discuss the performance index of the weighted factor of influence on control effect. And the uncertainty of vehicle parameters are taken into account, such as vehicle mass, the stiffness of suspension spring and tire. Design a controller based on the robust H<x> optimal control of active suspension to verify the robustness of the controller design;(4)Design a controller of drive force distribution based on sliding control to track the ideal yaw rate. Present an integrated control using active suspension and drive force distribution to improve the vehicle lateral stability and the vehicle roll and vertical dynamic response.