Performance of Anti-Lock Braking System Equipped Passenger Vehicles - Part I: Braking as a Function of Brake Pedal Application Force 2002-01-0304

This paper presents the results of original research conducted to evaluate the braking characteristics of passenger vehicles equipped with anti-lock braking systems (ABS) as a function of brake-pedal application force. The conditions studied in this paper are for braking on a dry, level roadway without any steering input. The objective of the paper is to study the effect of brake-pedal application force on the braking systems of common vehicles currently in-use. Comparisons are made between ABS and locked-wheel braking for each vehicle.

The subject of this paper is part of the general topic of passenger vehicle dynamics and stability. Knowledge of how a vehicle performs under a variety of braking conditions is important for a variety of applications such as 1) intelligent vehicle highway systems, 2) vehicle stability and control, 3) vehicle dynamics, and 4) accident reconstruction. To date, a number of studies have been performed to study the locked-wheel braking characteristics of passenger vehicles, but few studies have been published relative to how ABS-equipped vehicles perform with various brake-pedal application forces. Of interest is a better understanding of how typical passenger vehicles equipped with anti-lock brakes behave as a function of brake-pedal application force.

In our paper we present data obtained utilizing state-of-the- art data-acquisition systems for determination of brake-pedal application force effects on braking for a group of passenger vehicles equipped with ABS. We also present reduced and plotted data for the group of vehicles tested. The results provide an excellent understanding of how a variety of passenger vehicles equipped with anti-lock brakes perform as a function of brake-pedal application force during real-world braking conditions.

We found that braking average deceleration of a vehicle up to the point where the ABS begins to fully modulate the vehicle's brakes is significantly affected by the force applied to the brake pedal. Once the applied brake pedal force is sufficient to fully activate the ABS, braking performance tends to be slightly affected by increasing force - some vehicles have improved braking with increasing force, others have degraded performance. Both locked-wheel braking and ABS braking was found to vary between vehicles. We also found that ABS significantly improves braking relative to locked-wheel braking for some vehicles, but not others.