Citation

Blosser RD. Transp. Res. Rec. 1977; 621: 90-98.

Copyright

(Copyright © 1977, Transportation Research Board, National Research Council, National Academy of Sciences USA, Publisher SAGE Publishing)

DOI

unavailable

PMID

unavailable

Abstract

This paper describes how the torque characteristics of commercial vehicle brakes can be modeled and made part of a hybrid computer simulation of an antilock system. The braking system of a commercial vehicle is an open loop pneumatic-mechanical system with feedback controlled by the vehicle operator. To achieve optimum performance, i.e. short stopping distance and vehicle control, the vehicle operator must be aided by a brake control system which senses wheel velocity and acceleration, and then reduces excessive brake pressure and reapplies controlled brake pressure. Most systems in use today consist of an electronic computer, a solenoid controlled air valve, and wheel speed sensors. Design and analysis of this complex system require a combination of engineering simulation and experimental testing. In the simulation of a commercial vehicle antilock system, three areas are difficult to model; the air value system, the tire-road interface, and the brake drum/brake shoe interface. Their simulation is discussed along with techniques for verifying the accuracy of the models being used. Elements that make the study of the air brake stopping problem difficult are a surface friction range of 8 to 1, load variations of 10 to 1., and transitions in brake torques of 8 to 1. In addition to these factors, the effects of variable pneumatic delays and steering torgues must be considered along with the desire to produce a low cost, highly dependable, fail-safe/self-test unit.