Research On Nonlinear Model Predictive Integrated Longitudinal,Lateral, And Vertical Vehicle Stability Control For Electric Vehicle

At present,due to the energy crisis and environmental pollution,electric vehicles have become a hot spot in the field of automotive research.Distributed electric vehicles have the advantages of four-wheel independent controllability and fast motor response,which have brought many opportunities and challenges to the development of chassis electrical control systems.The chassis electric control system mainly improves the driving braking performance,handling performance and comfort performance of the vehicle through the control of the wheel hub motor,suspension and steering motor of the vehicle.The vehicle dynamics system is a strongly coupled nonlinear system.Due to the coupling relationship between the dynamics,the chassis electric control system cannot be simply decentralized under some extreme operating conditions.There is conflict between the subsystems.Therefore,the integrated control of the vehicle chassis control system is very necessary.According to the six-degree-of-freedom body dynamics model,a body motion controller based on model predictive control is designed.Then the particle swarm algorithm is used to solve the problem.Moreover,the tire force distributor is designed considering the tire load factor and actuator constraints,so as to optimize and obtain a reasonable tire longitudinal force,lateral force and vertical force.The specific work content is as follows:First,it introduces the research background and significance of electric vehicles,and explains the importance of chassis control.This paper summarizes the research status of electric vehicle in the vertical,horizontal,vertical,and vertical force control fields.By analyzing the chassis electric control field,the importance of studying chassis integrated control is obtained.Secondly,the coupling relationship between vehicle dynamics and tire force is analyzed,and a 15-degree-of-freedom vehicle dynamics simulation model,a tire model and a wheel motor model are established according to requirements for the simulation verification of the controller.Furthermore,the control structure of chassis integrated control is analyzed,and the layered chassis integrated control strategy is selected through analysis.Once again,the vehicle’s longitudinal,lateral and vertical force integrated controller is designed.First,the vehicle reference model is selected and the six-degree-of-freedom balance equation of the body is established.The control requirements of the body motion controller are analyzed,and the NMPC(Nonlinear Model Predictive Control)is as the core algorithm of the electric vehicle body motion control system.Aiming at this multi-objective and multi-constrained control problem,the objective function is designed,and the appropriate constraint conditions are selected.The particle swarm optimization algorithm is used to optimize the solution.Then the tire force distribution is designed to distribute the resultant force and resultant torque into 12 tire forces.Finally,under the simulink simulation environment,under the conditions of flat road and uneven road,the simulation experiments of linear acceleration and lane change wer e carried out.Use the vehicle model to verify the practicability of the motion controller.The simulation results show that the designed integrated controller improves the vehicle’s riding comfort under the conditions of ensuring the vehicle’s driving braking performance,handling performance and stable performance.