Research On Integrated Control Of Vehicle Stability Based On LMI Control Method

With the progress and development of science and technology,the driving speed of cars is constantly improving.At the same time,it is an urgent problem to protect the personal safety of drivers and passengers.Therefore,the stability and safety of vehicles driving at high speed have become a hot issue in research.In recent years,the research and application of vehicle active safety system have greatly improved the driving stability of vehicles and effectively guaranteed the personal safety of drivers and passengers.The active safety control system can intervene and operate the vehicle with the driver when the vehicle is unstable or about to become unstable,and improve the stability of the vehicle by adjusting the longitudinal force or lateral force.Among various chassis safety control methods,active steering control and active differential braking control can significantly improve vehicle driving stability and safety.When the vehicle is in the condition of instability,the active steering improves the stability of the vehicle by generating additional corner compensation into the steering system.Active braking is to apply different braking forces to each wheel according to the driver's driving intention and the driving condition of the vehicle,so as to form an additional yaw moment around the axle of the vehicle body and improve the driving stability of the vehicle.Active steering can improve the stability of the vehicle without affecting the longitudinal speed,and it will not affect the ride comfort of drivers and passengers.When the vehicle driving at low speed tires is in the linear working area,it is more effective to improve the stability of the vehicle by adjusting the front wheel Angle through active steering.However,when the tire's ground adhesion reaches its limit,it is impossible to improve the stability of the vehicle by changing the corner of the front wheel,and then the active steering will lose its effect.It is more direct and effective to improve the stability of the vehicle through differential braking and direct yaw torque control.According to the obvious characteristics of these two active safety control methods,this paper studies the integrated control strategy,applies robust control to the integrated control of active steering and active braking,and realizes better control by dividing the control area of active braking and active steering,so as to improve the stability of the vehicle.This paper based on the Linear Matrix Inequality(referred to as ‘LMI')robust control to establish the active steering controller,in order to verify the controller,need two degrees of freedom vehicle model is established,the pilot model and road model,and combined with the CarSim simulation,respectively in medium speed high adhesion road surface with high speed low adhesion road working condition of two kinds of simulation,to verify the effectiveness of the controller.Then,considering the model uncertainty and external interference,an integrated controller is established based on the robust control LMI method.According to the phase plane method,the active steering and active braking control areas are divided to avoid mutual interference in the control process.The integrated controller and CarSim were simulated jointly,and the control effect were obtained under two conditions of medium speed high adhesion road surface and high-speed low adhesion road surface,which verified the effectiveness of the integrated controller.Finally,the hardware based on LabVIEW RT is built on the ring test bed,and the control algorithm is tested on the bench,and the real control effect is obtained.