Anti-skid control system

A digital machine method for augmenting braking control of a braked wheeled vehicle employing fluid pressure operated wheel brakes, comprising the step of selectively modulating the fluid pressure applied to the valve of at least one braked wheel so as to cause the braking control to track the knee of the road torque and wheel velocity versus time envelope, which said step includes the set of iterative steps of

• preselectively relieving an applied brake pressure to said braked wheel in response to either wheel deceleration thereof being greater than a preselectively large first level or the combination of a wheel deceleration of a lesser preselected second level and a wheel velocity within a preselected first range of upper and lower velocity levels;
• and
• preselectively restoring an applied wheel brake pressure to said braked wheel for a period not in excess of a preselected first mode interval in response to said wheel deceleration being less than said second lesser deceleration level and said wheel velocity being at least equal to a second velocity level less than said first range of upper and lower velocity levels,
• and including an additional and antecedent initial step of
• modulating the applied fluid pressure as a preselectively delayed and progressively increasing attenuated single test pressure pulse for a preselected pulse time interval, the delay corresponding to the delay time of said valve and said pulse interval corresponding to the rise time of said valve.

A digital machine method for augmenting braking control of a braked wheeled vehicle employing fluid pressure operated wheel brakes, comprising the step of selectively modulating the fluid pressure applied to the valve of at least one braked wheel so as to cause the braking control to track the knee of the road torque and wheel velocity versus time envelope, which said step includes the set of iterative steps of

• preselectively relieving an applied brake pressure to said braked wheel in response to either wheel deceleration thereof being greater than a preselectively large first level or the combination of a wheel deceleration of a lesser preselected second level and a wheel velocity within a preselected first range of upper and lower velocity levels;
• and
• preselectively restoring an applied wheel brake pressure to said braked wheel for a period not in excess of a preselected first mode interval in response to said wheel deceleration being less than said second lesser deceleration level and said wheel velocity being at least equal to a second velocity level less than said first range of upper and lower velocity levels,
• and including an additional and antecedent initial step of attenuatively modulating the applied fluid pressure as a single initial test pressure pulse of a preselected pulse width.