Antiskid control system

Claim 2

An anti skid control system for a wheel comprising: input means for coupling to a signal source for receiving a first signal whose amplitude is a function of the speed of the wheel to be braked; differentiator means for differentiating said first signal from said signal source and providing an output signal whose amplitude is a function of the rate of deceleration of said wheel; said differentiator means including means for amplifying said differentiated first signal to provide said output signal, said means for amplifying said differentiated first signal including means for varying the gain of said amplifying means, the gain of said amplifying means being a function of the deceleration rate of the wheel; modulating means coupled to said differentiator means, said modulating means including means for generating a second signal whose amplitude is a function of a predetermined rate of deceleration, said predetermined rate of deceleration being greater than the maximum rate of deceleration of the vehicle, and circuit means responsive to saiD output signal, and said second signal and acting to produce a control signal which is substantially proportional to the time integral of the instantaneous difference of said output signal and said second signal, and output means for coupling said control signal to the operating circuit of an electrically operated brake pressure control valve of the wheel braking apparatus for the wheel.

Claim 3

In an antiskid system, means for generating a valve-controlling signal comprising means for producing a first signal voltage substantially proportional to wheelspeed; means for producing a second signal voltage substantially proportional to rate of change of wheelspeed; means for amplifying said second signal, said means for amplifying said second signal comprising an amplifier having a linear gain region of operation in response to said second signal, said amplifier having a further linear gain region of operation of higher value when said second signal representative of rate of change of wheelspeed exceeds a given value; means for producing a third signal voltage of predetermined value; means for comparing said amplified second signal with said third signal to provide a first control signal; skid detector means responsive to said first signal voltage for providing a second control signal, and means for adding said first and second control signals to provide said valve controlling signal.

Claim 4

In an antiskid system, means for generating a valve-controlling signal comprising means for producing a first signal voltage substantially proportional to wheelspeed; means for producing a second signal voltage substantially proportional to rate of change of wheelspeed; means for amplifying said second signal, said means for amplifying said second signal comprising an amplifier having a linear gain region of operation in response to said second signal, said amplifier having a further linear gain region of operation of higher value when said second signal representative of rate of change of wheelspeed exceeds a given value; means for producing a third signal voltage of predetermined value; means for comparing said amplified second signal with said third signal to provide a first control signal; skid detector means responsive to said first signal voltage for providing a second control signal, and means for adding said first and second control signals to provide said valve controlling signal.

Claim 5

Antiskid control means for a vehicle wheel comprising, in combination: means providing a first signal voltage the amplitude of which is proportional to wheelspeed; differentiator circuit means responsive to said first signal voltage for providing a second signal voltage proportional to the deceleration of said wheel; modulator circuit means responsive to said second signal voltage for providing a first control signal having an amplitude less than a predetermined value; skid detector means responsive to said first signal voltage for providing a second control signal having an amplitude greater than said predetermined value; means for controlling braking effort in response to said first and second control signals, and overtorque modulator means coupled between said skid detector means and said modulator circuit means.

Claim 6

Antiskid control means for a vehicle wheel comprising, in combination: means providing a first signal voltage the amplitude of which is proportional to wheelspeed; differentiator circuit means responsive to said first signal voltage for providing a second signal voltage proportional to the deceleration of said wheel; modulator circuit means responsive to said second signal voltage for providing a first control signal having an amplitude less than a predetermined value; skid detector means responsive to said first signal voltage for providing a second control signal having an amplitude greater than said predetermined value; means for controlling braking effort in response to said first and second control signals, and overtorque modulator means coupled between said skid detector means and said modulator circuit means.

Claim 7

Antiskid control means for a vehicle wheel comprising, in combination; wheel-braking apparatus for establishing a brake application on the vehicle wheel; said wheel-braking apparatus including an antiskid valve input circuit having an input terminal for receiving antiskid control signals; a first channel responsive to analog signals representative of wheelspeed derived from said wheel for generating a first control signal which is a continuous function of the rate of deceleration of said wheel over a predetermined range of rates of deceleration; a second channel responsive to analog signals representative of wheelspeed derived from said wheel for generating a second control signal when the difference in amplitude of said analog signals exceeds a predetermined value within a given time period; means for coupling said first and second control signals to said input terminal, and wherein said means for coupling said first and second control signals to said input terminal comprises a summing amplifier.

Claim 8

Antiskid control means for a vehicle wheel comprising, in combination; wheel-braking apparatus for establishing a brake application on the vehicle wheel; said wheel-braking apparatus including an antiskid valve input circuit having an input terminal for receiving antiskid control signals; a first channel responsive to analog signals representative of wheelspeed derived from said wheel for generating a first control signal which is a continuous function of the rate of deceleration of said wheel over a predetermined range of rates of deceleration; a second channel responsive to analog signals representative of wheelspeed derived from said wheel for generating a second control signal when the difference in amplitude of said analog signals exceeds a predetermined value within a given time period; means for coupling said first and second control signals to said input terminal, and wherein said means for coupling said first and second control signals to said input terminal comprises a summing amplifier.

Claim 9

Antiskid control means according to claim 4 wherein said first channel response time is less than the hydraulic response time of said wheel-braking apparatus.

Claim 10

Antiskid control means according to claim 4 wherein said first channel response time is 10 milliseconds or less.

Claim 11

An antiskid control circuit comprising: low-pass filter means for coupling to a signal source representative of wheelspeed; differentiator means including an amplifier coupled to said low-pass filter means and responsive to signals representative of wheelspeed from said signal source for developing an electrical current output signal representative of wheelspeed deceleration; Said amplifier means comprising an amplifier having a first linear gain region of operation and a second linear gain region of operation of higher value when said wheelspeed deceleration exceeds a given value; modulating means including a capacitor and a constant current discharge circuit coupled to said differentiator means, said modulating means including means including said constant current discharge circuit for generating a signal current whose amplitude is a function of a predetermined rate of deceleration, said constant current discharge circuit including variable resistance means for selecting said predetermined target rate of deceleration, and circuit means including said capacitor coupled to said constant current discharge circuit responsive to said output signal representative of wheelspeed deceleration, and said signal whose amplitude is a function of a predetermined rate of deceleration, and acting to produce a control signal current continuously over the range of 1 to 60 feet/second2 deceleration which is substantially proportional to the time integral of the instantaneous difference of said output signal representative of wheelspeed deceleration and said signal whose amplitude is a function of a predetermined rate of deceleration, and output means for coupling said control signal to the operating circuit of an electrically operated brake pressure control valve of the wheel braking apparatus for the wheel.

Claim 12

An antiskid control circuit comprising: low-pass filter means for coupling to a signal source representative of wheelspeed; differentiator means including an amplifier coupled to said low-pass filter means and responsive to signals representative of wheelspeed from said signal source for developing an electrical current output signal representative of wheelspeed deceleration; Said amplifier means comprising an amplifier having a first linear gain region of operation and a second linear gain region of operation of higher value when said wheelspeed deceleration exceeds a given value; modulating means including a capacitor and a constant current discharge circuit coupled to said differentiator means, said modulating means including means including said constant current discharge circuit for generating a signal current whose amplitude is a function of a predetermined rate of deceleration, said constant current discharge circuit including variable resistance means for selecting said predetermined target rate of deceleration, and circuit means including said capacitor coupled to said constant current discharge circuit responsive to said output signal representative of wheelspeed deceleration, and said signal whose amplitude is a function of a predetermined rate of deceleration, and acting to produce a control signal current continuously over the range of 1 to 60 feet/second2 deceleration which is substantially proportional to the time integral of the instantaneous difference of said output signal representative of wheelspeed deceleration and said signal whose amplitude is a function of a predetermined rate of deceleration, and output means for coupling said control signal to the operating circuit of an electrically operated brake pressure control valve of the wheel braking apparatus for the wheel.