Skid control system

Abstract

A skid control system is provided for use with a vehicle having a pair of spaced apart wheels and having a braking system for applying braking forces to the wheels. A brake control circuit responds to a skid signal obtained from any one of a plurality of incipient detector circuits to act upon the braking system to release the braking forces. A delayed skid signal is provided whenever the difference in wheel speeds of the two wheels exceeds a given amount. A delayed skid signal is also provided if the average wheel speed of the two wheels decreases at a rate greater than a desired decreasing rate. If both wheels decelerate, a skid signal is provided upon sensing that the faster wheel is decelerating at a rate greater than a reference rate. As the wheels spin-up toward an ideal velocity for a braked vehicle, an acceleration detector serves to insure wheel roll up on low friction surfaces. If the wheels spin up at an acceleration greater than an acceleration level, the acceleration detector output is inhibited. If the acceleration is less than the preceeding level and more than a second level, a skid signal is provided. Also, as the wheels spin-up to a desired velocity, braking forces are restored when the rate of acceleration declines below the second acceleration level. Monitoring circuits are provided for monitoring various operations of the skid control system and deactivate same when the operation is not within prescribed limits.