Performance, Robustness, and Durability of an Automatic Brake System for Vehicle Adaptive Cruise Control 2004-01-0255

Adaptive Cruise Control (ACC) technology is presently emerging in the automotive market as a convenience function intended to reduce driver workload. It allows the host vehicle to maintain a set speed and distance from preceding vehicles by a forward object detection sensor. The forward object detection sensor is the focal point of the ACC control system, which determines and regulates vehicle acceleration and deceleration through a powertrain torque control system and an automatic brake control system. This paper presents a design of an automatic braking system that utilizes a microprocessor-controlled brake hydraulic modulator. The alternatively qualified automatic braking means is reviewed first. The product level requirements of the performance, robustness, and durability for an automatic brake system are addressed. A brief overview of the presented system architecture is described. The control methodology of generating brake pressure via a hydraulic modulator to achieve the vehicle deceleration requested by ACC controller is then introduced. The paper includes a description of two Pulse Width Modulated (PWM) solenoid control designs and applications as an important technology to ensure the automatic braking performance. The implementation of moding the automatic brake system with ABS, Traction Control, and Vehicle Stability Control is revealed at the vehicle system level. Vehicle test data will be presented as insight to the braking performance and robustness. The control-related system durability will also be examined and discussed under vehicle testing profiles. Vehicle integration system test data summarizes and concludes the practice and value of the presented automatic brake system for vehicle adaptive cruise control.