Control Implementation And Strategy Research Of Hill Descent Control System In Sport Utility Vehicle

Hill descent control(HDC)system is a part of ADAS(Advanced Driver Assistant System)technology.It is an expanding function of ESC(Electronic Stability Control).This function mainly do timely and effective active brake intervention according to the road surface condition and the movement state of vehicle.Meanwhile,the driving speed is controlled with safe speed on the downhill.There is no need to control any pedal.So the driver only needs to focus on steering wheel,and easily smooth downhill at a low speed.This paper is based on the research achievement of vehicle dynamics and control group in the state key laboratory of automotive safety and energy,Tsinghua University.It is starting from the actual project,research and develop hardware realization prototype,control strategy of HDC based on ESC.Then verify the prototype and strategy by vehicle tests with CS75 of Changan.Firstly,vehicle model is established,including the longitudinal motion,the lateral movement of vehicle and the rotation of four wheels.At the same time,the longitudinal and lateral load transfer is considered in vehicle motion process.Tire model uses magic formula which used widely in tire mechanics analysis.Then via analysis of system requirements,controller program is set based on modular design.And successfully develop a prototype through selection of components,schematic design,wiring,PCB board production,components procurement,welding,testing and so on.It consists of power conversion,CAN communication,acceleration sensor,motor drive,solenoid valve drive,MCU module,etc.Meanwhile,the control strategy is determined by research and benchmarking,take speed as control target and design PID regulator of wheel cylinder pressure increment.Research and calibrate pressure characteristics of HCU(Hydraulic Control Unit)can realize precise control of pressure.The vehicle tests show that the HDC controller prototype and the control strategy reached the enterprise test's standard.It is of great significance for the engineering application of braking safety technology for the downhill vehicle.