Research On Trajectory Tracking And Stability Integrated Control Of Distributed Drive Electric Vehicle

At present,electric vehicles have become the main focus of the development of the automotive industry.Compared with other drive forms of electric vehicles,distributed drive electric vehicles with hub-wheel motors as the direct power source have the following outstanding advantages: the structure is simple,using hub motor drive,which improves the energy transmission efficiency and the torque response is fast;provides the torque vector control method,which can continuously adjust the controlled state of the vehicle,and provides a basis for achieving better stability control technology.This paper takes distributed drive electric vehicles as the research object,starting with active safety control technology,for vehicles driving at a high speed on the road with high adhesion coefficient,it is easy to have rollover accidents.While driving on the road with low adhesion coefficient,it is easy to have slip and tail accidents,and in the extreme condition of track tracking due to vehicle instability,easy to cause the failure of trajectory tracking.And in the extreme condition of track tracking due to vehicle instability,easy to cause the failure of trajectory tracking.In order to improve the driving stability and trajectory tracking performance of vehicles on road with different adhesion coefficients,this paper studies the anti-rollover stability control,lateral stability control,trajectory tracking control and integrated control of the vehicle,and based on the model predictive control algorithm(MPC)design the corresponding controller.The main research contents are as follows:1.Establishment of vehicle dynamics model and vehicle state observation based on UKF.Firstly,research on the longitudinal,lateral,yaw and roll dynamics characteristics of the vehicle,established the vehicle’s plane four-wheel,single-track dynamics model and roll dynamics model,which provided the basis for the design of each MPC controller.Secondly,a tire model was established according to the magic tire formula.Considering that obtaining accurate vehicle state quantities in real time is the key point of vehicle stability control.We use UKF to design state observer for real-time observation of vehicle lateral speed,yaw rate,roll angle and roll rate,these states will be used to vehicle state prediction and rollover index calculation.2.Research on the vehicle’s roll and lateral stability control.First,the vehicle’s roll and lateral stability control objectives and control methods are selected.The roll stability controller and lateral stability controller are designed based on the MPC algorithm.Then,under the simulation environment,completed the MPC roll stability controller high adhesion coefficient road and high-speed fishing hook steering conditions test,and the MPC lateral stability controller low adhesion coefficient road,high-speed snake steering conditions test.The simulation results show that the above MPC controllers effectively limit the control target within the threshold range by generating additional torque.Realize the stability control of the vehicle under extreme conditions.3.Research on the integrated control of vehicle stability.Aiming at the problems that a single controller has poor adaptability on roads with different adhesion coefficients and cannot achieve the expected control effect.In order to improve the control effect of the control system in different working conditions,research on the selection of the conditions for determining the stability state and the formulation of coordination strategies,the MPC stability integrated controller is designed based on the hierarchical integrated control system.The upper supervisory decision module of the controller includes the coordination controller,and the lower executive control module includes the MPC controllers.And completed the high-speed,docking road simulation test.The simulation results show that the MPC stability integrated controller effectively improves the vehicle stability control effect under complex working conditions.4.Research on the stability control of vehicle trajectory tracking.We designed the vehicle trajectory tracking controller based on MPC algorithm,introducing the establishment of the objective function and the setting of constraint conditions in the controller design process.Then through the simulation test,the influence of different working conditions on the trajectory tracking control effect is analyzed.In order to improve the stability and trajectory tracking accuracy of the vehicle during high-speed trajectory tracking,the MPC trajectory tracking control system was improved,combined with the MPC stability integrated controller,the trajectory tracking stability controller was designed.And conducted a simulation comparison test,the simulation results show that the MPC trajectory tracking stability controller effectively reduces the lateral load transfer coefficient and the side slip angle during the vehicle high speed trajectory tracking process.Under the premise of ensuring the stability of the vehicle,the trajectory tracking performance of roads with different adhesion coefficients is improved.5.In order to better meet the actual demand,the stability control experiment was carried out on the real vehicle platform.Designed the vehicle lateral stability controller and trajectory tracking stability controller on the Simulink platform,on the existing distributed drive electric vehicle experimental platform in the laboratory,firstly,several lateral stability control experiments were carried out with different control modes,and the effectiveness of the proposed lateral stability controller was verified.Then the trajectory tracking stability control test was carried out.The test data shows that during the trajectory tracking of the vehicle,the opening of the stability controller effectively reduces the yaw rate and lateral acceleration on the premise of ensuring the accuracy of trajectory tracking.