Study On The Control Strategy Of Vehicle Stability Based On ESP

ESP(Electronic Stability Program) is a very important technology in the field of automotive active safety. It can through the regulation of the engine torque and wheels braking control to prevent the car from over-steering and under-steering situations,and improve the car’s handling stability and safety performance completely at the same time.Firstly,the basic principles of ESP was researched in this paper, the nonlinear tire model based on "Magic Formula",the vehicle model with seven degrees of freedom and two degrees of freedom model were built by using Matlab/Simulink. Then relations characterization of vehicle stability was analyzed on the basis of the vehicle lateral dynamics, and the yaw rate and vehicle side slip angle are confirmed to be control variables.Directed against the difficulty with measuring side slip angle, evaluation approach to side slip angle designed based on the theory of expansion of observation was adopted and simulated. Directing against the complexity,nonlinear, time-varying characteristics of vehicle system,a kind of self-adaptive neuro-fuzzy ESP controller was designed based on adaptive neuro-fuzzy inference system namely ANFIS, which adapted to the changes of the vehicle speed and the road adhesion coefficient according to vehicle information.Selection logic of brake wheel of ESP system was built by using Matlab/Stateflow.Lastly, simulation experiment in different working conditions was done to validated the ESP control system designed in this paper.The results of simulation experiment showed that the effect of control method designed in this paper was better off, which not only can prevent vehicle from instability,but also have good adaptive and robustness.