Research On Control Strategy Of Steer-by-wire System For Automatic Driving And Driving Assistance

With the development of smart cars,the functional safety of the steering system is becoming more and more perfect.The steer-by-wire system has the advantages of improving the driver’s driving experience,improving the passive safety of the vehicle and improving the stability of the vehicle,and has a good development prospect.In recent years,autonomous driving technology has developed rapidly,and autonomous driving technology has been divided into different levels,from low-level driving assistance to advanced automatic driving,and the way the automatic driving controller controls the steering has also changed from "human-machine co-driving" to "Machine-oriented" transition.Starting from these two backgrounds,the paper studies the control strategy of the steer-by-wire system when it is controlled by different levels of automatic driving controllers,that is,the realization of the dynamic corner requirements of the automatic driving controller,and the steering control based on the understanding of the driver’s intention.The right to switch content such as codriving with man-machine,driving experience,functional safety,etc.In the research process,it is mainly divided into three parts,which are the research on the control strategy of the steer-by-wire system,the research on the control strategy of automatic driving and the research on the control strategy of driving assistance.On-line control steering system control strategy.First,the composition of the steering wheel reaction force is studied,and the method of combining the reconstructed steering load and the observed steering load is adopted.Secondly,the position control of the steering execution motor is studied,and the three closed-loop method of feedforward and feedback is adopted.In terms of autonomous driving controlled strategies.It adopts the control method of steering execution part control strategy,on the basis of three closed loops of feedforward and feedback,combined with fuzzy control,it has good control effect under different working conditions.After that,the driver’s takeover strategy was studied,and the driver can accurately judge the driver’s takeover.In terms of driving assistance controlled strategies.Improved on the basis of the control method of the automatic driving control strategy.First,the method of anti-integration saturation is studied for driving assistance conditions,and then the method of steering control right transfer is used to improve the shortcomings of anti-integration saturation.Finally,the judgment of steering control transfer is studied.It can accurately determine that the driver takes over the steering wheel and exits to take over the steering wheel.A controlled strategy was designed for the lane centering system,and the test bench was carried out.A hardwarein-the-loop steering-by-wire test platform was built to verify the designed controlled strategy.