Skid control system

Claim 2

A skid control system of a wheeled vehicle having a plurality of wheels and braking system for effecting braking of the wheels, said skid control system comprising: first means for providing a first signal having a magnitude indicative of the slip between the vehicle and at least one wheel of the vehicle, second means for modulating the braking at least at that one wheel in response to said first signal attaining a selected magnitude indicative of a preselected magnitude of slip, and an accelerometer for sensing frictional variations between the one wheel and the driving surface said second means varying the selected magnitude of said first signal at which brake modulation occurs in response to frictional variations between the one wheel and the driving surface as sensed by said accelerometer and with variation in vehicle speed.

Claim 3

The system of claim 1 with said first means including accelerometer means for providing a second signal indicative of the deceleration of the vehicle, said first means including velocity means for providing a velocity signal having a magnitude varying in accordance with the magnitude of the vehicle velocity, said second means responsive to said second signal and said velocity signal for varying the selected magnitude of said first signal at whIch brake modulation occurs in accordance with variations in the magnitude of said second signal and said velocity signal.

Claim 4

The system of claim 2 with said first and second means as responsive to said first, second and velocity signals providing brake modulation at lower magnitudes of slip for lower magnitudes of vehicle deceleration and at lower magnitudes of slip for lower magnitudes of vehicle velocity.

Claim 5

The system of claim 3 with said first means further comprising velocity means for providing a third signal having a magnitude varying in accordance with variations in magnitude of the speed of the one wheel, integrator means responsive to said second signal for providing a fourth signal representative of the integral of said second signal and hence the integral of the vehicle deceleration, sample means responsive to actuation of the brake system and to said third signal for providing a fifth signal having a magnitude indicative of the velocity of the wheel prior to actuation of the brake system, and computer means responsive to said fourth and fifth signals for providing said velocity signal and responsive to said third and velocity signals for providing a seventh signal having a magnitude indicative of the slip between the vehicle and that wheel.

Claim 6

The system of claim 4 with said second means comprising reference means for providing an eighth signal having a magnitude indicative of said preselected magnitude of slip at which brake modulation occurs and being varied in magnitude in accordance with variations in magnitude of said second and velocity signals, said computer means responsive to said seventh and eighth signals for providing an output signal in response to the relative magnitudes of said seventh and eight signals having a predetermined relationship, and modulating means responsive to said output signal for modulating the braking at that one wheel.

Claim 7

The system of claim 5 with said output signal being provided when the magnitude of said eighth signal exceeds the magnitude of said seventh signal.

Claim 8

The system of claim 3 with said first means further comprising velocity means for providing a third signal having a magnitude varying in accordance with variations in magnitude of the speed of the one wheel, integrator means responsive to said second signal for providing a fourth signal representative of the integral of said second signal and hence the integral of vehicle deceleration, sample means responsive to actuation of the brake system and to said third signal for providing a fifth signal having a magnitude indicative of the velocity of the wheel prior to actuation of the brake system, said second means comprising reference means for providing a reference signal having a magnitude indicative of said preselected magnitude of slip at which brake modulation occurs and being varied in magnitude in accordance with said second and velocity signals, computer means responsive to said fourth and fifth signals for providing said velocity signal and responsive to said third, fourth, fifth and reference signals for providing an output signal in response to the relative magnitudes of said third, fourth, fifth and reference signals having a predetermined relationship, and modulating means responsive to said output signal for modulating the braking at that one wheel.

Claim 9

The system of claim 7 with said predetermined relationship occurring when the slip as determined by said third, fourth, and fifth signals exceeds said preselected magnitude of slip as determined by said reference signal.