Study On Lateral Stability Control Strategy For Car

When cars are turning on the road with low adhesion coefficient or in high speed, the lateral force of the tire usually attains to the physical limit and the vehicle dynamics stability will be lost because of the exoteric disturbance or turning, so the traffic accidents frequently happen. Electronic Stability Program (shortened as ESP) can stabilize the vehicle behavior under the limit situation by controlling longitudinal forces on four wheels independently. At present, ESP has become the international research focus in the vehicle active safety field and it is gradually equipped to the moderate and top cars; while in china, the research in this field has just started. So, to study ESP has great significance for our country and also has broad application prospect.First of all, the function and the construction of the vehicle stability control system are introduced; the history of the vehicle stability and its present status are discussed; the contents of the dissertation are also put forward in this part. And then the researches about the vehicle out of control are carried on.According to this the control method and control variables are discussed. Based on the analysis, the thesis takes the yaw raw as the main control variable and the vehicle slip angle as the assistant control variable. And the target control variables are mainly discussed. Including;(1)The single wheel model is analyzed in detail, and state how the key parameter of the Acckermann Equation——characteristic vehicle speed is going with vehicle mass, the cornering stiffness and the center mass. According to this a new way of calculation of the target yaw rate and corrected based on the vehicle speed is introduced. (2) The control effect is evaluated by the simulation. (3) How to calculate the vehicle slip angle is also introduced in this chapter based on the analysis of the vehicle dynamic.Based on Chapter Three the whole Electronic Stability Program is introduced in detail. Including the identification of the vehicle state, the release precondition of the control, the active brake control and the algorithm based on slip PID control. A whole Electronic Stability Program is given according to all above. And it is also establish a steady foundation for the simulation analysis.Finally,the article applied the widespread software-Matlab/Simulink to establish the entire vehicle model and control algorithm model. The ESP control strategy within the closed loop and open loop and testified the operating mode simulations of the single lane, double lane, S lane and the step wheel angle. By the simulation analysis under both the open loop and closed loop of ESP system, it can get the conclusion that the car with ESP control can achieve the anticipant driving situation and the control strategy of this dissertation is correct.The thesis analyzed the vehicle dynamic state, improved the calculation of the target yaw rate based on the single wheel model, and introduced the whole ESP control strategy. By the simulation analysis under both the open loop and closed loop of ESP system, it can say that The ESP control system can effectively improve the stability of the vehicle under high-speed steering or low friction coefficient circumstance so as to assist the drivers'steering operation.