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

With the widespread application of new technologies such as information communication,Internet,big data and artificial intelligence in the automotive field,electrification,intelligence and networking have become the development trend of the automotive industry.Automobiles are being transformed from manually controlled mechanical products to intelligent products controlled by intelligent systems.Intelligent distributed electric vehicles have become a research hotspot in the automotive industry.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(cstc2018jcyjAX0422),this paper analyzes the variable angle transmission ratio characteristics of the steer-by-wire system,the front wheel steering control and active steering control strategy based on the research at home and abroad,A fractional-order PID control method based on fractional calculus theory is proposed to improve the driving comfort and active safety of distributed electric vehicles.The main research contents of this paper include:(1)Distributed electric vehicle dynamics modeling.Firstly,the"modular"modeling idea is used to establish the SBW system steering operation and actuator dynamics model,the hub motor dynamics model,by improving the Carsim vehicle dynamic model,the Carsim/Simulink joint simulation model of distributed drive electric vehicle is established,which lays the foundation for the control strategy validation in the following chapters.(2)Design of ideal variable transmission ratio for steering by wire.Aiming at the problems existing in the fixed transmission ratio of the steering system,a design strategy of the steering by wire variable transmission ratio based on the vehicle speed,the steering wheel angle and the yaw rate gain is proposed to reduce the driver's burden and improve the stability of the vehicle..(3)Active control of steering angle based on fractional order control theory.Based on the control strategy of corner feedback,using fractional order control theory and Oustaloup filter method and particle swarm optimization algorithm,a SBW system steering angle fractional PI~?D~?controller is established to improve the stability of steering wheel angle tracking performance.(4)Vehicle stability control based on SBW system.Combined with the dynamic model of distributed electric vehicle,the vehicle's driving stability under extreme conditions is taken as the goal.The control characteristics of active steering fractional-order PI~?D~?control algorithm of SBW system for vehicle handling stability are studied to improve the lateral stability of distributed electric vehicle.