Research On Design And Control Strategy Of Multi-mode Steer-by-Wire Execution System

The global automobile industry is transforming and upgrading towards the direction of deep integration of electric,intelligent,connected and shared.Meanwhile,it is inseparable from the progress of chassis-by-wire technology.At present,the technology of steer-by-wire has become one of the cores to promote the development of chassis-by-wire technology,and it is also the key technology to ensure the active safety and handling stability of electric and intelligent vehicles.In order to improve the handling stability and safety of the steer-by-wire vehicle under extreme conditions and realize the independent control of the front wheel slip angle,in this study,the present status of steer-by-wire system is investigated,a multi-mode steer-by-wire execution system is proposed,and the mathematical model of the system is established.On this basis,the angle following control strategy,angle decision control strategy and mode switching control strategy are further established,and the proposed control strategy is simulated and verified by the joint simulation platform.Specifically,this paper studies the following four aspects:First,a multi-mode steer-by-wire actuator configuration is proposed and the corresponding model is established.The structure of the proposed electric multi-mode steer-by-wire system is described in detail,and the working principle of different modes is clarified.Then,the parameter design and modeling of the components of the steer-by-wire execution system are completed.Finally,the total steering resisting torque is calculated,and the simulation model is built on the Matlab/Simulink for the simulation verification of the control strategy.Secondly,a multi-mode steer-by-wire actuator control strategy is proposed.The overall architecture of the control strategy is proposed.Secondly,the control strategy for permanent magnet synchronous motor is designed,and the motor control algorithm based on SVPWM is built.Then,the nominal model of the steer-by-wire system with aligning torque is established.Based on the nominal model and the global sliding mode controller,the steering angle tracking controller of the steer-by-wire system is designed.Finally,the proposed multi-mode steer-by-wire actuator control strategy is simulated and analyzed.Thirdly,the variable transmission ratio and angle distribution strategy of steer-by-wire is designed.A multi-mode steer-by-wire actuator simulation platform is built,and a single-point preview driver model is established.Next,a multi-gain fusion variable transmission ratio based on genetic algorithm optimization is designed.The simulation results show that the designed transmission ratio can achieve steering sensitivity at low speed and steering stability at high speed.Then,the vehicle stability controller based on sliding mode control is introduced.Finally,through the angle decision strategy based on control distribution and the tire inverse model,the angle decision strategy under different modes is obtained.The simulation results show that the proposed control strategy can improve the yaw stability of the vehicle by redistributing the tire lateral force load.Fourth,vehicle state estimation and model switching strategy design.The key state parameters of the vehicle are estimated based on the SRCKF algorithm.The normal load of the tire is estimated by analyzing the normal load composition of the tire,and the tire model is established based on the magic tire formula.Next,the mode switching strategy of the multi-mode steer-by-wire actuator is designed by considering the normalized tire cornering stiffness.Finally,the corner allocation strategy and mode switching strategy are verified by building a joint simulation platform.Finally,the full text is summarized,and other issues to be further explored in the research process are prospected.