Design And Simulation Of An Active Steering Mechanism Based On A Passenger Car

Steering system is an important device to control the vehicle running route and direction,and its performance has a direct influence on the vehicle handling and stability.To steer by wire is on behalf of active steering system can according to different vehicle speed,through the motor input so as to change the steering transmission mechanism,taking into account the low-speed steering sensitivity and steering at a high speed stability.However,in their own brands,the vehicle is equipped with steering very rare.This phenomenon appears on the one hand is the cost considerations,more on the reliability of the system is to make the.The front wheel active steering system(AFS)is added to the steering wheel angle by the planetary wheel mechanism.Even in the case of motor failure,the steering performance of the vehicle is not completely lost.In this paper,an independent brand models for the platform.On the premise of analyzing the performance of the vehicle,the AFS system is deployed to the whole vehicle system.AFS control system is designed,and the performance of vehicle handling and stability is improved by comparing with AFS in the simulation environment.Firstly,this paper summarizes the current domestic and foreign research results of the active steering system,expounds the significance of the active steering system,and summarizes the design requirements and functions of AFS.In the second chapter,considering the factors such as the cost of processing,proposes a novel double row wheel rotation mechanism.On the basis of analyzing the characteristics of the double planet wheel drive,the electric drive system and the specific parameters of the planetary mechanism are selected and designed.Then this paper analyzes the problems existing in the current AFS control strategy: 1 using the theoretical formula to calculate the variable transmission ratio curve.2 focus only on the control effect of the vehicle to allow the maximum rotation angle(which represents the PID control strategy).This selection of MSC.Adams vehicle suspension model is established,using AMESim AFS steering system model,the AFS mainly and steering tube column is velocity coupling,in order to ensure the steering motor is stable,this paper uses PID closed-loop control angle of AFS motor control,guarantee the performance of the AFS system.On this basis,this paper integrates ADAMS and AMESim into Simulink,and selects variable transmission ratio feed forward control and optimal control as the control strategy of AFS.And the control strategy is integrated into the simulation environment,respectively,on the car in the steering wheel angle step,steady static circular,double lane change and sweep to four different vehicle speed performance under typical working conditions analysis and comparison.The motor angle of motor and steer wheel torque are shown for all the cases.Simulation results show that the equipment AFS active steering system of automobile steering gear ratio changes with the change of speed changing,in the set speed can control transverse vehicle yaw rate gain,to ensure the stability of the driving performance of the,at the same time optimal control system,and constantly revised the body of the vehicle sideslip angle and transverse angular velocity,reduce the vehicle in steering process in the yaw angular velocity fluctuations,and reduce the vehicle side slip angle.