Anti-skid brake control system which optimizes frequency of pressure build-up pulses

Claim 1

An anti-skid brake control system for a motor vehicle having at least one road wheel, said system comprising a speed sensor associated with said at least one wheel for producing a circumferential wheel speed signal V R , means for determining a vehicle acceleration b x , brake pressure control means for reducing the brake pressure, maintaining the brake pressure constant for a maintenance phase, and increasing the brake pressure in pulsed increments, evaluation circuit means responsive to said wheel speed signal V R for determining a wheel acceleration V R , an acceleration difference V=V R -b x , an actual wheel slippage λ, a stable wheel slippage λ s , and a slippage difference Δλ=λ-λ s , said evaluation circuit means generating a stability criterion P y =α(b 1 -V) (Δλ-Δλ 1 )+β(Δλ-Δ.lambda. 1 ) during a maintenance phase following a pulsed increment, where α, β, b 1 , and Δλ 1 are constants, said evaluation circuit means producing control signals which cause said brake pressure control means to (1) increase brake pressure by a pulsed increment when at least one of Δλ<Δλ 1 and V>b 1 occurs; (2) further maintain the brake pressure constant when 0<P y <a, where a is a constant; and (3) reduce the brake pressure when P y >a.