Anti-skid control system for motor vehicle

An anti-skid control system for a motor vehicle, including a brake fluid pressure buildup-control mode and a brake fluid pressure reduction mode, each of which occurs in anti-skid cycles, said anti-skid brake control system comprising:

• first valve means for alternately building-up and holding brake fluid pressure during said brake fluid pressure buildup-control mode;
• second valve means for reducing brake fluid pressure during said brake fluid pressure reduction mode;
• wheel speed measuring means for measuring a speed of each wheel of the motor vehicle and for providing a wheel velocity signal V.sub.W responsive to said speed;
• peak detecting means for receiving said velocity signal V.sub.W and for determining a high peak value V.sub.HP and a low peak value V.sub.LP of said velocity signal V.sub.W when a wheel is braked;
• controller means for repetitively opening and closing said first valve means during said brake fluid pressure buildup-control mode, from a first time when said velocity signal V.sub.W has said high peak value V.sub.HP to a second time when said velocity signal V.sub.W has a value R, said value R corresponding to said velocity signal V.sub.W being equal to a reference velocity V.sub.WO at the second time, said reference velocity V.sub.WO having an initial value at the first time being less than said high peak value V.sub.HP by a predetermined velocity value .DELTA.V, having values which vary between the first time and the second time dependent upon a gradient, and having a final value equal to said velocity signal V.sub.W at the second time corresponding to said value R;
• acceleration measuring means for measuring wheel acceleration during a time after detection of said low peak value V.sub.LP by said peak detecting means on the basis of said velocity signal V.sub.W between a first value Va and a second value Vb of said velocity signal V.sub.W, said first value Va being dependent upon a predetermined rate of wheel velocity and said low peak value V.sub.LP, said second value Vb being dependent upon another predetermined rate of wheel velocity and said first value Va;
• determining means for determining at least one of said predetermined velocity value .DELTA.V, said gradient .theta. and an initial pressure buildup time T.sub.P, for said brake fluid pressure buildup-control mode in accordance with said measured wheel acceleration;
• and
• reduction control means for controlling opening of said second valve means during said brake fluid pressure reduction mode, from a time corresponding to an occurrence of said value R until a time corresponding to an occurrence of said low peak value V.sub.LP of said velocity signal V.sub.W.