Research On Handling Stability Control Of Distributed Drive Electric Vehicle

As a new energy vehicle,electric vehicles have become a critical direction for the current automotive industry due to their ability to effectively address the two major problems of energy crises and environmental pollution caused by traditional fuel vehicles.Among them,distributed drive electric vehicles driven by hub motors have the advantages of more controllable degrees of freedom and fast response time,and are attracting much attention.However,the mounting of wheel hub motors will increase the unspring loaded mass of the vehicle,which affects the vehicle handling stability;the nonlinear change of tire force brings new challenges to the coordinated control of maneuverability and stability.This study focuses on the distributed drive electric vehicle and employs vehicle dynamics theory to investigate the "estimation of critical state parameters","analysis of factors affecting handling stability","stability judgment",and"coordinated control of handling and stability".The aim is to improve the vehicle’s handling stability.The main research contents are as follows:(1)Vehicle dynamics model was built and simulation experimental research was conducted.A vehicle dynamics model including body,wheels,tires,motor,and driver model was built in MATLAB/Simulink software,and simulation tests were conducted.The accuracy of the constructed model was verified by comparing it with the vehicle model in CarSim platform,which provided the model basis and simulation test environment for the subsequent study.(2)The state parameter estimator is designed based on the extended Kalman filter algorithm and the traceless Kalman filter algorithm.The simulation tests of the angular step condition and single lane change show that the accuracy of the two state parameter estimation algorithms is within the acceptable range.The absolute value of the estimation error of the state parameter of the traceless Kalman filter algorithm is only 0.08 degree and 0.05 degree,which can accurately evaluate the key state parameters to meet the requirements of coordinated control of vehicle handling stability.(3)The mechanism of the influence of the key control variables,yaw rate and side-slip angle,on the handling stability are analyzed.In order to investigate the influence of the change of hub motor mass on the handling stability,the steering return and steering torque input tests are conducted as examples.The steering return simulation test shows that the response peaks of side-slip angle and yaw rate increase with the increase of hub motor counterweight under the low and high velocity conditions,and the increase of yaw rate is greater.Torque step input simulation tests show that the amplitude of yaw rate,lateral acceleration and side-slip angle increase with the increase of hub motor counterweight,and there is a certain lag in the time to reach their respective peak values.To provide a theoretical basis for the implementation of coordinated control of handling stability.(4)Based on the idea of stability domain boundary coefficients and hierarchical control,a joint control strategy architecture that integrate the maneuverability and stability was proposed.By using the phase plane analysis method,the influence of changes in vehicle speed and road adhesion coefficient on the stable region boundary is analyzed,and the boundary parameters of the stability domain of side slip angle-side slip angular velocity under different road surface adhesion coefficients are given.Adopting fuzzy PID theory and sliding mode theory,the sideslip angle and yaw angular velocity tracking controllers are designed respectively,and the joint control strategy of self-adjustment of weight coefficient with road adhesion coefficient was designed.Simulation experiments under single lane change and step input conditions show that the integrated control strategy can effectively improve the vehicle handling stability and has certain robustness to the change of hub motor counterweight compared with the single control strategy.