Research On The Steering-by-wire Vehicle Active Control Strategy Based On The Variable Angle Ratio

The steering-by-wire system of the vehicle can control it with variable steering ratio and active steering according to the driving state of the vehicle.It is important to improve the handling stability,active safety and driving comfort of vehicle.This paper is aimed at the variable angle transmission ratio design and active steering control strategy of the vehicle steering-by-wire system.The main research contents are as follows:At first,the structure and the working principle of the steering-by-wire system are analyzed in this paper.The dynamics model of the steer-by-wire system is built by the using of Matlab/Simulink,and embedded into the CarSim vehicle model,to build the full steering-by-wire vehicle model.The second,the steering system characteristic of vehicle is analyzed,in order to reduce the driver's burden,the design scheme of variable angle transmission ratio of the vehicle steering system is proposed,in this paper,the variable angle transmission ratio of the steering system is determined based on the constant value of vehicle yaw rate gain,and the yaw velocity value is optimized,the variable angle transmission ratio of the steering system is determined by the optimized yaw rate gain,and the variable angle transmission ratio is modified by fuzzy control,so as to realize the variable angle transmission ratio feedforward control of vehicle steering-by-wire system.On the basis of the feedforward control of vehicle variable steering angle ratio,active steering control strategy based on yaw rate dynamic feedback is studied,using the extension theory to extend the performance of traditional sliding mode controller,and design the extension sliding mode controller,the steering-by-wire system of variable angle transmission ratio active steering control model is established.Finally,in order to verify the efficiency of the relevant control strategy,CarSim/Simulink joint simulation experiments are carried out.The experimental results of the typical working condition which are selected show that the proposed control strategy can improve the vehicle handling stability.