Study On Fault Tolerant Control Of Stability Of Electric Vehicle Steering By Wire

As an important part of automatic driving of electric vehicles,steer-by-wire system replaces the mechanical connection between steering wheel and steering wheel by using electric control technology and bus technology,which not only improves driving portability and vehicle comfort,but also brings many safety risks.Among them,the sensor as the signal measurement and transmission tool in the electronic control technology,once the fault occurs,the mechanism will lose contact,which will seriously affect the safety and stability of the vehicle.Therefore,it is very important to adopt effective sensor fault-tolerant control strategy to ensure the stable driving of the drive-by-wire vehicle.In this paper,the active fault-tolerant control strategy for the sensor related to steering stability is studied considering the variation of parameters and time-varying characteristics of sensor measurement noise of the drive-by-wire electric vehicle.The main work is as follows:(1)Determine the fault-tolerant control object.Based on the analysis of the structure and principle of the steer-by-wire system,the sensors related to the steering stability of the vehicle were selected as the research object of fault tolerance,and the typical burst faults were modeled and analyzed.The influence of sensor errors on the stability of the vehicle was summarized respectively.(2)Establish the simulation model of electric vehicle with drive-by-wire steering.Considering vehicle longitudinal,transverse and horizontal pendulum and four wheel rotation,using MATLAB/Simulink built wire control steering system,the vehicle tire model simulation platform,at the same time the wire control steering system model import Carsim,choose different adhesion coefficient of road surface of two kinds of simulation platform for a variety of steering condition test,compare simulation with body information,verify the accuracy of vehicle dynamic model proposed.(3)Set the active fault-tolerant control strategy for the steer-by-wire sensor.Considering the change of the total vehicle mass caused by the number of passengers on and off the vehicle when the electric vehicle is running,the recursive least square method is used to identify the vehicle mass online.Considering that the sensor is affected by variable noise,the state estimation of the front wheel rotation sensor is carried out by using the fuzzy adaptive extended Kalman filter algorithm combined with the quality identification results.Then,the fault diagnosis and fault tolerance compensation of the sensor are realized by combining residual theory and data fusion method,and the simulation is verified by Matlab/Simulink.Simulation results show that when a single sensor fails,the proposed method has better anti-noise performance and approximation ability,and its fault tolerance control precision is significantly improved compared with the traditional fault tolerance control method.(4)A modified drive-by-wire steering electric sightseeing car was selected for real vehicle experiment.One is to identify the quality of the whole vehicle under different working conditions,the other is to set up two typical burst faults of the front wheel Angle sensor to carry out fault tolerant control experiment verification.The experimental results show that the quality identification algorithm can track the real vehicle quality in a short time under different working conditions,and the fault-tolerant control algorithm is applicable to the two kinds of sudden faults of the front wheel Angle sensor,which can effectively improve the safety and stability of the steer-by-wire system.