Research On ESP Immune PI Control & Vehicle Velocity Estimation Methods For RWD Light Bus

More and more consumers and automobile manufacturers have been paying attention to Automotive Active safety system. ABS (Anti-lock brake system) and TCS (Traction control system) get the optimum vertical dynamics performance by controlling wheel vertical sliding rates. And ESP (Electronic Stability Program, also called vehicle stability control systems) can control vehicle behavior in accordance with the driver's intention with the control strategy is expounded respectively when the vehicle are oversteered and understeered under critical situations.ESP research mostly includes two aspects content--research of ESP control algorithm and vehicle state parameter estimate algorithm. ESP control algorithm control algorithm is the key technology of ESP control and vehicle state parameter estimate algorithm is the foundation of ESP research. Velocity is one of the important vehicle state parameter. Therefore, this paper mainly researchs immune PI control algorithm and vehicle velocity estimation algorithm of electronic stability program system.This paper mainly includes four parts:In the first part, the significance,function, control methods and construction of vehicle ESP system are introduced. The history of the ESP system and its present status is discussed. In the second part, dynamics simulation models is built, which comprise several key parts of vehicle, such as engine, transmission, tire and whole vehicle and etc.In the third part, based on ESP control strategy, immune algorithm are used to correct nominal yaw rate of vehicle and design the parameters self-adjusting control algorithm of PID controller for yaw moment correction of the vehicle. The system has two parameters: yaw rate and slip angle. There are four methods. (1)vehicle yaw rate feed back control (2)vehicle slip angle feed back control (3)yaw rate is used to adjust the parameters of PID controller while slip angle feed back control (4) slip angle is used to adjust the parameters of PID controller whileyaw rate feed back control. Under Matlab/Simulink circumstance, validate the effect of immune PID control algorithm in three maneuvers of steering step-input,instancy transformation lane and snake road through software-in-loop simulation. The results show that immune PID control algorithm can make the yaw rate approach to the nominal value and limit the slip angle using the first and the fourth methods. But the second and the third methods are not work well. Through the brake, the method of controlling the yaw rate directly is more effective. So ESP control algorithm in which yaw rate is used as the main control parameter and slip angle is used as assistant parameter is more effective. In the meantime,based on establishing the polling list of vehicle yaw rate feed back control,this paper proceeds hardware-in-loop testing .This test further verifies ESP Immune PI Control & Vehicle Velocity Estimation methods.The fourth part presents two schemes of longitudinal velocity estimate of ESP and two schemes of lateral velocity estimate of ESP. ESP apply ABS and TCS as the under control.This requires to calculate the slip rate and input it to ABS and TCS. However, slip rate depends on practical velocity. In the meantime, current side slip angle estimate depends on vehicle longitudinal and lateral velocity. Therefore, velocity estimate has already been the key technology of ESP development. Due to vehicle longitudinal and lateral velocity estimate at the same time, so this paper firstly estimates longitudinal velocity and then estimates lateral velocity.Based on the sensor signal , this paper presents two schemes of longitudinal velocity estimate of ESP and two schemes of lateral velocity estimate of ESP.