Research On Combined Slip And Yaw Control Algorithm Of Electronic Stability Program For Light-duty Vehicle

ESP (Electronic Stability Program), through online vehicle sensor system, in real-time, monitors the intent of driver and driving condition, identifies and assesses the vehicle steering character and the trend of control-losing, through engine torque and wheels brake control, and prevents vehicle from understeering and oversteering. ESP enables vehicle to realize driver`s steering intent, and at the same time, improves its stability and direction performance. Since ESP was installed as vehicle initiative safety device, it has prevented a large number of traffic accidents, and has created significant social and economic benefits. At present, ESP, ABS (Anti-lock Braking System) and TCS (Traction Control System) have been integrated into a new generation of ESP, whose key technology and market have been mastered in Europe, North America, Japan, and other countries enjoying more developed auto industry. However, in China, both the ESP assembly rate and the research on ESP technological development are in the initial stages. In this paper, basis of foreign car ESP technology research experience, the content and implementation of research are settled, and according to"Research on Combined Slip and Yaw Control Algorithm of Electronic Stability Program System for Light-duty Vehicle", the main contents are described as below:(a) ESP Electronic Control Unit (ECU) DesignFirst, the ECU hardware circuit design programmer is given, according to the ECU functional requirements and the ESP input and output signal characteristics analysis. ECU using MC9S12DP512 produced by Freescale Semiconductor as MCU microcontroller, the clock circuits, power supply circuits and reset circuit of MCU minimum system are designed. Then, minimum system MCU peripheral hardware circuits,including HCU solenoid valve, electric pump drive circuits, vehicles state signal input port and control signal output port, are designed: HCU solenoid valve circuit uses TLE6216 smart quad channel low-side switch as drive chip, and electric pump circuit uses BTS6144 Smart Highside Power Switch as drive chip, produced by Infineon Semiconductor. Finally, based on CodeWarrior for HCS12 IDE(Integrated Development Environment), the hardware circuit function for inputting pulse signal, analog signal and outputting PWM signal, digital signal are tested by software programming.(b) Combined Slip and Yaw Control Algorithm of ESP Based on Fuzzy, Neural Network and PID ControllerBased on combined slip and yaw control algorithm, fuzzy and PID controller of ESP & fuzzy and neural network controller of ESP are proposed. According to the ESP system requiring the realization of the driver`s desirable track and the maintaince of the stability of driving control, Yaw rate is presented as a key control variables in this paper, using yaw torque calculated by PID or neural network controller to maintain driving stability. Moreover, slip angle is an important parameter to describe driving track and to maintain control. For the reason that there are some deviations in slip angle measurement and estimate, so fuzzy controller is used to monitor slip angle. The slip angle fuzzy controller monitor, in real-time, adjusts nominal yaw rate correction factor, through combined slip and yaw control algorithm achieving vehicle stability driving in limited conditions.(c) Combined Slip and Yaw Control ESP Offline Simulation and Hardware In-the-loop Test Based on Fuzzy, Neural Network and PID ControllerThrough offline simulation and hardware in-the-loop test, the effectiveness of fuzzy and PID controller of ESP & fuzzy and neural network controller are tested. Based on identifying target model ESP offline simulation platform and hardware in the loop test bench, offline simulation environment and hardware in-the-loop test environment are built, through Goal-driven vehicle dynamics model integrated with the hardware and software of Control system. And Researches on the effectiveness and adaptability for the control algorithm by offline simulation and hardware in the loop test are presented.According to control algorithm offline simulation and hardware in the loop test, come the following conclusions:(1) After the ECU board completed, through tests, the effectiveness of inputting pulse signal, analog signal and outputting PWM control signal, digital signal have been tested. Further control algorithm software will be written and embedded into ECU with ESP hardware in-the-loop test bench.(2) Through Goal-driven vehicle dynamics model offline simulation and hardware in the loop tests, the effectiveness of fuzzy and PID controller of ESP & fuzzy and neural network controller of ESP have been tested, tests results show that:â‘ the control algorithm of ESP can make the vehicle in accordance with the desirable track of the driver, and the deviation of the yaw rate nominal value and actual value is controlled in a certain range;â‘¡the absolute value of slip angle is restricted in smaller scope, by using the fuzzy controllerâ‘¢As BP neural network has good adaptability and online learning ability, and yaw toque is outputted by neural network controller directly, its effect of yaw rate nominal value tracking actual value is better than that of PID algorithm, and its timeliness is better than that of neural network PID algorithm.Compared with ABS and TCS, ESP can significantly improve stability and direction handling of the vehicle in limited condition by wheel brake control, etc, and cater to the development trend of automotive technology. The ECU hardware circuit design and combined slip and yaw control based on fuzzy, neural network and PID controller, provide some reference value for researching on"Combined Slip and Yaw Control Algorithm of Electronic Stability Program System for Light-duty Vehicle".