Research On The Longitudinal Control System Of Distributed Drive Electric Vehicle

With the development of society and science,the automobile industry develops rapidly in the world,which makes people’s life more convenient.While cars provide convenience for people’s life,they also produce a series of problems,such as traffic accidents,energy consumption and environmental pollution,especially in cities.In order to solve the above problems,the state vigorously promotes the development of new energy and intelligent driving vehicles,hoping to reduce the dependence on traditional energy and environmental pollution through the development of electric vehicles;at the same time,through intelligent driving,reduce the labor intensity of drivers,and avoid safety accidents caused by fatigue driving or weather factors.Based on the distributed drive electric vehicle platform,this paper carries out the research on the longitudinal control strategy of intelligent driving,and studies the control strategy of the implementation layer such as the longitudinal motion drive and braking of the vehicle.The main work is as follows.(1)Based on the fact that fuzzy control does not rely on accurate mathematical model,a multi-mode switching control strategy based on fuzzy control is established by simulating the driver model and combining with the analysis of vehicle longitudinal driving conditions.In this mode,the vehicle operation conditions are divided into cruise condition,approach condition,follow condition and collision avoidance condition.In each condition,the control strategy is designed based on fuzzy control,and a multi-mode switching control strategy is established to realize the stable and reliable switching of vehicle cruise,approach,tracking and active collision avoidance functions with the change of vehicle spacing,speed and acceleration,so as to ensure the driving safety And road utilization.(2)The drive and brake development plan and control strategy design of the executive system based on the longitudinal control of electric vehicles.In the design of the drive system,the in-wheel motor parameters of the distributed drive are determined according to the vehicle’s power performance requirements,and the torque control scheme is adopted during the driving process;when the braking system is designed,combined with the characteristics that all four wheels of the distributed drive electric vehicle can provide electric power,Determine the ideal braking force distribution curve for the front and rear axle braking force distribution.When the electric mechanism power and friction braking force are distributed,fully consider the characteristics of the motor and battery,and combine the control requirements of the vehicle’s multi-mode longitudinal control strategy to establish a compound system suitable for the model.The dynamic control strategy further improves the energy recovery rate under the premise of ensuring the safety and comfort of driving in the longitudinal control of the vehicle.(3)A joint simulation model based on Matlab\Simulink and Carsim is established,and the feasibility of the control strategy is verified through the simulation analysis of the efficiency of the braking system and the energy recovery rate under typical working conditions.(4)Carry out simulation analysis in combination with common longitudinal cruising conditions,approaching vehicle conditions,following conditions,collision avoidance conditions and comprehensive operating conditions to verify the adaptability of longitudinal control and compound braking control strategies under single and comprehensive operating conditions.The results show that: the longitudinal control strategy and its implementation system designed in this paper can well meet the requirements of vehicle longitudinal control,and the vehicle safety,comfort and energy recovery rate meet the requirements.