Research On Yaw Stability Integrated Control Of Electric Wheel Driving Vehicle Active Steering

Due to concerns about the environment and energy crisis,countries around the world are vigorously promoting the development of electric vehicles.Electric vehicles driven by hub motors have higher energy conversion efficienc y,simpler chassis mechanical structure and better control performance,which have become the focus of current research on electric vehicles.Since the wheels of the assembled hub motor are eas y to be controlled independently,in order to improve the vehicle's motion performance at high speed,this paper integrated control the vehicle's active steering and tire force distribution based on the model predictive control algorithm.In this paper,the horizontal motion of vehicles is anal yzed,and a sev endegree-of-freedom dynamic model including longitudinal,lateral,yaw and four-wheel motion is established.Considering that both steering and tire force distribution are influenced by tire characteristics,the tire model is established with the magic ti re formula,and the tire characteristics are tested under various working conditions through CarSim software simulation.Considering the dynamic characteristics of vehicle running horizontally,a four-wheel active transition prediction controller is design ed by using two degrees of freedom models of side and yaw.In order to improve the vehicle running stability,a four-wheel active steering yaw rate tracking control with zero side slip angle is propos ed,and the rear wheel turning angle with the additional front wheel turning angle are solved by the quadratic programming method using the constrained predictive control model.Under the premise of ensuring the yaw rate,the controller reduces the vehicle side deviation and improves the vehicle steering stability.Matlab/Simulink and CarSim are used for simulation verification.Aiming at the coupling problem of integrated control of steering and tire force distribution,this paper analyzes that steering and tire force affect vehicle yaw response,and pro poses to use additional yaw moment to weaken the interference between the two control systems.On the basis of the prediction controller,considering the influence of tire characteristics and vertical load,the friction circle constraint is added to optimi ze the tire force distribution control.Using the idea of hierarchical control,the integrated control of steering and tire force distribution is realized.Finally,the simulation software is used to verif y the feasibility of the control algorithm,which indicates that the joint driving force distribution of four-wheel active steering can better guarantee the stable driving under the limit condition.