An improved ABS control method incorporates entry criteria for initiating ABS
control based on brake pedal position and rate of depression, adaptively adjusted
by a reference pedal position corresponding to a predefined vehicle deceleration.
A periodically-updated characterization of the relationship between brake pedal
position and vehicle deceleration is used to establish the reference brake pedal
position, and when insipient wheel lock is detected, the initiation of ABS control
is delayed by an entry delay period that decreases with increasing rate of pedal
depression and with the degree to which the pedal position exceeds the reference
pedal position. In this way, the entry conditions are predicated primarily on the
manner of brake pedal depression, with adaptive adjustment for variations in braking effectiveness.
