Yaw Stability Model Predictive Control Of In-Wheelmotor Electric Vehicle

In-wheel-motor electric vehicle(IWMEV) represents the future of electric vehicle with its fundamental change of chassis structure and driving mode from the traditional car.However, recently researches of the vehicle stability meanly pay attention to the feature of the lateral and longitudinal dynamics without considering the influnences of verticle dynamics. Therefore, this paper focuses on the stability of IWMEV with the vertical dynamics influence to improve the performance of vechicle on complex road conditions with theoritical and practical significance.Firstly to propose the dynamic model of the vehicle considering the coupling relation of lateral and roll dynamics, the thesis established vehicle lateral, yaw, roll three degree of freedom coupling dynamics model. Then conduct the coupling relation of lateral and roll dynamics by analyze the tire load, tire model and tire elliptic constraints. To get the anti-rollover roll range we analysis phase trajectory of roll dynamics. Thus, given a and linear model of two degrees of freedom considering lateral, yaw dynamics with constraint of yaw rate to prevent rollover.Based on the proposed model, a constrained model predictive controller was established in the third chapter with the yaw control algorithm and torque vectoring strategy. To reach the control target of yaw stability control with rollover prevention, reasons of steering and rollover problem, the affecting factors are analysised. Then,simulations were carried out by high precision vehicle dynamics model ve DYNA on condition of high speed and large angle and serpentine steering to validate the feasibility and effectiveness of the controller.Then in view of the problem of trajectory deviation and sideslip during steering on low coefficient road in the fourth chapter a decoupling control of yawrate and side-slip angle was proposed. Further considering the anti-slip constraint and steering trajectory tracking demand, by analysis the influence factors of the problem. The simulation were carried out on low adhesion coefficient road and large rotation and serpentine steering condition to prove the efferctiveness of the control strategy.Finally, a rapid control prototype and a Hardware in loop(HIL) test platform was established with real-time simulation system dSPACE to test the above yaw controllers. To meet the demand of real-time the implicit model prediction control is improved into the explict model predictive control,then tests are finished on the platform which can simulate IWMEV’s status and control strategy conducted the stability and reliability of the controllers,and can be put into practicle vehicle tests.