Research On Wire-controlled Active Steering Control Of Distributed Drive Electric Vehicle

With the increasing energy crisis and environmental pollution,new technologies such as information communication,Internet,big data and artificial intelligence have been widely applied in the field of automobiles,the automobile also is accelerating to the intelligent system control transformation,the intelligent automobile becomes this domain another new hot direction.Distributed drive electric vehicles directly provide power to the wheels through the motor,which has the advantages of high transmission efficiency and high specific power,and can achieve independent control of the drive or braking torque of each wheel.The steer-by-wire(SBW)system is an important assembly for intelligent distributed electric vehicles to achieve active steering.The in-depth study of the control characteristics of the steer-by-wire system can improve the steering stability of distributed electric vehicles,it has certain research value for realizing intelligent driving and horizontal active control of vehicles.Based on the research contents of the national key research and development project(2016YFB0100905)and the Chongqing Basic Research and Frontier Exploration Project(cstc2018jcyj AX0422),Based on the research at home and abroad,the characteristics of variable angle transmission ratio,Front Wheel Angle tracking control and active steering control strategy are studied,a front wheel angle tracking control method based on fractional order PID control,and studies the stability of distributed electric vehicles active steering by line based on fuzzy control,so as to improve the handling and stability of distributed electric vehicles.The main research contents of this paper include:(1)Distributed electric vehicle dynamics modeling.Based on Simulink platform to build the System dynamics model of steer-by-wire SBW and the distributed electric vehicle model are built,and the simulation analysis is carried out respectively.The accuracy of the SBW model is verified by comparing with the Carsim Vehicle dynamics model,it lays a foundation for the following research work.(2)Design of variable transmission ratio for steer-by-wire system.Aiming at the problems of fixed transmission ratio of steering system,the design strategy of variable transmission ratio based on constant gain of yaw rate and constant deflection of center of mass is put forward,according to the ideal Yaw rate and the sideslip angle of the center of mass,the proportional coefficient is adjusted to improve the stability of the vehicle.(3)Research on angle tracking control strategy of steer-by-wire.Based on the angle feedback control strategy,the fractional PID controller is established by using the Fractional-order control theory and the GOA optimization algorithm to improve the stability of the angle tracking control performance.(4)Research on vehicle stability control of steer-by-wire system.Combined with the vehicle dynamics model of distributed electric vehicle,the active steering controller was designed,and the genetic algorithm was used to optimize the mold and the controller and the rule,to improve the handling stability of distributed electric vehicle.