Research On Vehicle Stability Control On Steering And Braking Maneuvers

With the improvement of the car’s driving speed,there is growing emphasis on vehicle stability.The vehicle steering brake is a very easy to break the situation,alone ABS system is difficult to meet the stability requirements of the limit conditions.This paper presented the control strategy of active front wheel steering system and active braking system coordinated control vehicle steering braking stability.The mathematical model of the vehicle was set up in CarSim software.Since the active front wheel steering model could not be designed in CarSim,the active front wheel steering mechanism model was established by Matlab / Simulink.The vehicle model is established by CarSim and Matlab / Simulink.The vehicle model was simulated and verified.Aiming at automobile stability control system of the characteristics of strong nonlinearity and time vary,the active front wheel steering sliding mode control strategy based on yaw rate is designed.Aiming at the "chattering" phenomenon of sliding mode control,a radial basis function(RBF)neural network optimization algorithm is proposed to optimize the switching gain of the sliding mode control strategy,and the active front wheel steering system control strategy was simulated and verified in CarSim/Simulink.The active braking sliding mode control strategy based on the combination of yaw rate and centroid side angle was designed.The influence of each wheel brake on the yaw moment is analyzed,and the wheel braking force distribution strategy is established.The modeling and simulation of active brake sliding mode control was simulated and verified.The control characteristics of the active front wheel steering system and the active braking system were analyzed,and the control range of the two systems is understood.Combined with the phase plane analysis method,the logic control rules of the coordinated control system are developed.Aiming at the situation of the simultaneous operation of the two systems,the fuzzy control weight allocation is proposed to optimize the coordination control strategy.And the simulation results show that the stability of the active front wheel steering system and the active braking system is correct and effective for the stability of the vehicle.Through the analysis of the stability of the linear time-delay system,the influence of the time-delay system on the stability of the steering brake was analyzed.When the time lag exceeds a certain time,the vehicle is obviously unstable.The Smith predictive compensation strategy was designed to eliminate the time delay of the original system.The simulation results show that the Smith predictive compensation strategy can eliminate the time delay of the steering brake system and improve the stability of the steering system.