Research And Development Of Control Strategy For Steering Drive System

The steering by wire system(Referred to as SBW)is an electrically controlled steering system which eliminating the mechanical connection between the steering wheel and the steering wheel,providing the possibility of a free design of the steering gear ratio.SBW system is important for improving vehicle handling stability,driving comfort and active safety.Based on the National Natural Science Foundation of China(No.51775155),the design of ideal steering ratio and the strategy of Active steering have been studied.This paper aims at the characteristics of the SBW vehicle.Firstly,the composition and working principle of the SBW's subsystems have been analyzed,each subsystem dynamics model has been mastered,the kinematic characteristics and its transfer function of the steering drive system have been focused on research,and the system parameters have been identified according to the experimental data,The transfer function of the system has been determined and modeled on Simulink,Once the Simulink model of the steering drive system has been combined with the vehicle's CarSim model,the SBW vehicle model has been established.Which can be used as an experimental platform for the subsequent research and control strategy of the SBW system.Secondly,when the SBW control strategy has been studied.The impact of vehicle handling through different gear ratios has been analyzed,a set of ideal transmission ratios has been determined based on a constant yaw rate gain,a design method of SBW variable ratio has been proposed,the ideal transmission ratio has been modified and optimized throughout the speed range,according to the demand of "low speed easy and fast,high speed stability",the SBW vehicle have been feedforward controlled by the ideal transmission ratio MAP which has been corrected and optimized.Compared with the traditional vehicle,the simulation results show that the vehicle handling stability based on SBW control has been improved.Finally,in order to enhance the comfort and safety of vehicle handling,the neural network advanced control algorithm has been used to dynamically adjust the steering wheel angle based on the vehicle state parameter feedback,and the active steering control strategy has been designed.The simulation results show that the vehicle handling stability of the active steering controller has been improved obviously compared with the traditional vehicle.