Research On Algorithm Of Vehicle Stability Control System Under Accelerating Conditions

Vehicle Stability Control (VSC) can improve lateral stability of vehicle,and restrain under-steering and over-steering. Now, VSC is the international research focus in the vehicle active safety field. Vehicle stability control system is gradually equipped to the moderate and top cars; while in china, the research in this field is at very beginning. In Chapter One, the function and the construction of vehicle stability control system are introduced; the history of the vehicle stability and its present status are discussed; the contents of the dissertation are put forward. The dissertation pays more attention to control algorithm and simulation of vehicle stability control. Based on the abroad achievements in this field, the following issues are discussed: Developing of dynamics simulation software; the design of control logic and simulation of software-in-loop and hardware-in-loop. There are six chapters in the dissertation. In Chapter Two, dynamics simulation software o is built. A vehicle model can describe the vehicle non-linear characteristics under limit condition is needed for simulating vehicle stability control system. This chapter adopts Gim tire model in tire's ISO coordinate, in which the tire's longitudinal slip property and lateral slip property are considered. Except for tire model, the dynamics simulation software is a 7-DOF vehicle model, which including engine model, brake model, driveline 75吉林大学硕士学位论文model, vehicle model, assistant model and driver model. Finally, Simulink modelof dynamics simulation software and graphics user interface based on Matlab areworked out. In Chapter Three, control algorithm of vehicle stability control is broughtforward. The error of yaw rate can represent vehicle's steering characteristics.When slip-angle is very large, driver can't control vehicle by steering wheel. Sothe errors of yaw rate and slip-angle are chose as control parameter of stabilitycontrol. The nominal yaw rate and nominal slip-angle are confirmed by the twodegree of freedom vehicle model (bicycle model). Yaw rate PID control,Slip-angle PID control and Yaw rate and Slip-angle Fuzzy PID control areapplied to yaw moment control. By yaw moment distributing logic, the bestbraking wheel and target brake pressure are confirm. In Chapter Four, validate the effect of control algorithm of vehicle stabilitycontrol system, a simulation study is made on driver step input, single lane inputand sin input. In view of driver's influence, fuzzy PID control is made on driverstep input and double lane input. In Chapter Five, hardware-in-loop simulation is worked out. Simulationresults indicate that yaw angle rate PID control and slip-angle PID control canimprove lateral stability of vehicle. Chapter Six is the summary and conclusion of the dissertation. The following conclusions can be derived from the simulation study of vehiclestability control system when vehicle is accelerating and steering. 1. Software in loop simulation can quicken the development of vehicle stability control algorithm. By use of Matlab software, Software in loop and hardware in loop simulation plat can be built very easily. 2. Yaw angle rate and slip-angle are very important control parameter of vehicle stability control system. The lateral stability of vehicle can be enhanced by controlling yaw angle rate and slip-angle. 3. Hardware in loop simulation can quicken the development of vehicle stability control algorithm. The simulating model and control algorithm 76ABSTRACT can be validated.