Research On Fault-tolerant Control Strategy Of Steering-by-wire For Multi-source Data Fusion

In recent years,the automotive industry in China has developed vigorously towards unmanned,intelligent and electronic direction.The traditional steering operation of cars has gradually shifted from human control to electronic intelligent system control,resulting in a new type of automotive steering system called "Steer by Wire"(SBW)system.In automotive design,safety has always been the first factor to consider.The SBW system requires more sensors than traditional steering systems to provide signals for the system’s operation.However,sensors,as electronic components,inevitably encounter malfunction during practical use.Once a malfunction occurs,it will affect the accuracy of the signal,and an incorrect signal input into the control system will have a severe impact on the upper-level control algorithm.Therefore,faulttolerant control of the sensors is crucial for the SBW system.This article conducts research on fault-tolerant control of the SBW system.Firstly,the structural characteristics and principles of the SBW system are analyzed,and a model is established for the key components of the system.The dynamic equation of the three-degree-of-freedom nonlinear vehicle mathematical model is given,and a joint simulation platform of Carsim/Simulink is built to complete the construction of the vehicle model.Secondly,to solve the fault-tolerant problem of the front-wheel steering angle sensor,a fusion algorithm based on an Unscented Kalman Filter(UKF)is proposed through research and analysis of multi-source data fusion algorithms.An automotive state estimator is designed to use easily obtainable vehicle state information to obtain difficult-to-measure real-time vehicle state parameters.Based on this,common faults of the front-wheel steering angle sensor are modeled,and the above state observer is used to diagnose the faults of the angle sensor.Subsequently,a front-wheel steering angle observer is designed to reconstruct the fault signal to achieve fault-tolerant control of the sensor.The simulation experiments show that the designed fault-tolerant controller for the front-wheel steering angle can achieve real-time diagnosis,timely isolation,and reliable fault-tolerance for common types of wheel angle sensor faults.Finally,as a fault-tolerant measure for sensor faults in upper-level control,the lateral torque of the car is taken as the control object.A controller based on an immune adaptive sliding mode algorithm is proposed,with the aim of minimizing the lateral deviation angle and path error of the vehicle,ensuring stability and precision during the steering process.The controller can enable the vehicle to track the ideal trajectory in real-time when disturbed,and the lateral deviation angle remains at an ideal state under different road conditions.Simulation results show that the designed active steering controller can accurately track the ideal trajectory under different operating conditions,the actual transverse angular velocity deviates less from the ideal value,is insensitive to external disturbances,has excellent robustness,and improves driving stability.