Research On Direct Yaw Moment Control For In-wheel Motor Electric Vehicles

Vehicle electrification has become the major trend of vehicle technology development under the fact that the global energy crisis and environmental pollution are increasingly serious.Compared with the traditional internal combustion engine vehicle,the distributed drive electric vehicle is driven by independent and controllable hub motor,and the mechanical transmission structure in the traditional internal combustion engine vehicle is replaced by the wire control system with higher transmission efficiency and faster response,which makes the distributed drive electric vehicle have more prominent control advantages.The handling stability of the distributed drive electric vehicle can be improved by designing more reliable stability control strategy,and then,the incidence of traffic accidents can reduce effectively.The dissertation,based on the key industry innovation chain(group)project of Shaanxi Province(2018ZDCXL-GY-05-03-01)"Research on the key technology of distributed driving pure electric passenger vehicles" and the youth project of the Basic Research Program of Natural Science of Shaanxi Province(2020JQ-381)“Research on the Intelligent Coordinated Control Strategy of Distributed Drive Electric Vehicle DYC/AWS System”,is about the research of distributed drive electric vehicle direct yaw moment control strategy.The main research contents are as follows:The whole vehicle subsystem is modularized,and the seven freedom model,driver model,wheel motor model and tire model are built under the MATLAB / Simulink simulation environment.The whole vehicle control strategy research and development platform is built,and the effectiveness of the whole vehicle simulation model is verified under typical tests.This paper analyzes the necessity of observing vehicle state parameters and road surface parameters,designing joint observer of vehicle state parameters and road surface parameters by using unscented Kalman filter algorithm,which correlates vehicle state observer and road surface parameter observer to form closed-loop feedback correction.The real-time observation of vehicle state parameters and pavement parameters is carried out,and the observation results of the joint observer are verified in the simulation conditions of high adhesion coefficient pavement and docking pavement.The yaw rate and the sideslip angle of the linear two freedom model working in the steady-state test are selected as the control objectives.The additional yaw moment controllers based on the model predictive control and the "feedforward + feedback" control are designed respectively.The effective set method of quadratic programming is used to optimize the distribution of the additional yaw moment between the wheels,and the driver’s closed-loop and open-loop simulation are designed to test and compare the performance of two kinds of additional yaw moment controllersCombined with the characteristics of the distributed drive electric vehicle and the principle of direct yaw moment control,a double-layer structure direct yaw moment controller is designed.The yaw rate and the sideslip angle of the linear two freedom model working in the steady-state test are selected as the control objectives.,and the upper additional yaw moment controllers based on the model predictive control and the "feedforward + feedback" control are designed respectively.Taking the minimum utilization of tire adhesion as the optimization objective,according to the working characteristics of motor system and braking system to design constraints,with which the effective set method of quadratic programming is designed to optimize the distribution of the additional yaw moment between the wheels.Finally,the performance of two kinds of additional yaw moment controllers is tested under the driver’s closed-loop and open-loop simulation.