Research On Coordinated Control Of Active Front Wheel Steering And Active Stabilizer Bar

With the continuous upgrading of automotive technology,the active function of the chassis has increased,but it brings multi-system integration problems.Active Front-wheel Steering(AFS)has variable steering ratio function by additional steering degrees of freedom;the Active Stabilizer Bar(ASB)can adjust roll stiffness of suspension,through the active torsional moment,to control roll attitude and reduce the risk of rollover.Based on future chassis technology integration,this paper has conducted in-depth research on the coordinated control of these two new technologies.Firstly,the vehicle dynamics model,the actuator model and the driver model were built using MATLAB/Simulink~?,and the theoretical verification and analysis were carried out by Carsim~?.Secondly,for the AFS,the ideal steering ratio curve is designed by S function,the additional steering angle is calculated,the actuator performs angle follow-up control to realize the dynamic variable steering ratio;for the ASB,design the roll angle target with piecewise function,and calculate the active moment by the sliding mode control law,the bottom actuator produces the torque.Then,among the multi-system integrated control methods,it is pointed out that the decentralized control performance is limited,the centralized control scalability is poor,and the coordinated control is the preferred architecture.Furthermore,by theoretically analyzing the coupling relationship between two systems,a functional layered framework is proposed:the upper layer fuzzy PID controller coordinates the middle layer systems based on the vehicle yaw motion state,and corrects their controller outputs;the bottom-layer actuator completes the closed-loop control according to the command to realize the coordinated control.At the same time,considering the failure of the stabilizer bar actuators,the reconfiguration control strategy is designed to improve the fault-tolerant capability of the system.Finally,the step,sinusoidal steering under open-loop conditions and the single-shift line and double-shifted maneuver under closed-loop condition based on the driver preview model are set up.The offline simulation of the design algorithm is carried out;The AFS and ASB joint bench built by dSPACE was used for rapid control prototype test.The results of simulation and bench test show that the coordinated control algorithm can improve the yaw maneuverability and the stability of roll.The fault-tolerant algorithm can improve the stability of the vehicle under the failure condition of the actuator.