Study On Integrated Chassis Control For Distributed Drive Electric Vehicles

Distributed drive electric vehicles do not have a complicated mechanical transmission system,and have multiple independent motor drive systems,which can flexibly achieve torque distribution between drive wheels,providing a foundation for the realization of advanced chassis control systems such as direct yaw-moment control.In addition,based on the distributed drive structure,electric vehicles can realize the integration of multiple chassis control systems(such as active steering and active suspension),thereby greatly improving the dynamic performance of electric vehicles.However,when multiple chassis control systems are working at the same time,if there is no reasonable coordination of the control functions of each system,then each system may conflict,thereby affecting the control effect and even invalidating the control system.Therefore,it is necessary to deeply study the control mechanism of each chassis control system for an electric vehicle with a distributed drive structure,and rationally design a chassis integrated control strategy that can coordinate the control effects of multiple systems.In view of this,this article takes the distributed drive(independent drive by left and right of the rear axle)electric vehicle equipped with a front-wheel steer-by-wire system as the object,and conducts research from the following aspects:1)Combined with particle filter estimation algorithm,a vehicle state estimator is designed based on the vehicle plane kinematics model.The estimator model does not rely on any tire force information and does not require additional design of tire force estimator,simplifying the calculation of the estimator At the same time,it can avoid the introduction of tire models in the estimator,resulting in the reduction of the estimation accuracy of the vehicle state due to the tire model errors.In order to change the standard deviation of the process noise component and reduce the accuracy of the vehicle state estimator due to different external factors such as traffic and road conditions,an adaptive standard deviation is used instead of a fixed standard deviation to improve the state transition equation.On the MATLAB/Simulink and Car Sim simulation platform,the designed adaptive vehicle state estimator is simulated and verified.The simulation results show that the designed estimator can be used to simulate the longitudinal and lateral speed of the car under different simulation conditions.There are more accurate estimation results.2)The control mechanism of the active front wheel steering system and the direct yaw moment control system are analyzed.Based on the three-degree-of-freedom vehicle dynamics model,the expression of the change amount of yaw angular acceleration is derived,and the steering state of the car is characterized The change trend of the qualitative analysis and summary of the influence of the additional rotation angle of the front wheel and the transfer of the driving force of the rear axle between the left and right drive wheels on the yaw movement of the car.Based on the influence law,AFS and DYC sliding mode controllers are designed to control the vehicle’s handling stability.The simulation results show that the designed AFS and DYC control systems can effectively ensure the stability of the vehicle,and the correctness of the obtained influence law is verified.3)In-depth analysis of the working methods and principles of the AFS and DYC integrated controller based on the method of dividing the work area,summing up its existing defects,and proposed the AFS and DYC integrated control strategy based on the multi-input multi-output control structure to improve it.Based on the hierarchical design structure of the automobile stability integrated control system,an integrated controller based on the phase plane theory to divide the work area of the subsystem and an integrated controller based on the multi-input multi-output control structure are built.The results show that the proposed integrated control strategy based on multi-input and multi-output structure has better control effect under different working conditions,which can improve the defects of the integrated control strategy based on work area division and effectively ensure that the vehicle state follows the target value.Significantly improve the handling stability of the car.