Apparatus for generating a lead signal in an antiskid system

• US 4,484,281 A
• Filed: 08/17/1982
• Issued: 11/20/1984
• Est. Priority Date: 05/05/1980
• Status: Expired due to Term

• Current Assignee: Crane Company
• Original Assignee: Crane Company
• Inventors: Skarvada, Thomas
• Primary Examiner(s): Chin, Gary
• Application Number:
  US06/408,864
• Time in Patent Office: 826 Days
• Field of Search: 364/426, 303/91, 303/95, 303/97, 303/99, 303/105, 303/106, 303/107, 303/109, 188/181 C
• US Class Current: 701/71
• CPC Class Codes: B60T 8/17616 Microprocessor-based systems

Abstract

An antiskid braking system includes an improved apparatus for generating a lead signal to provide lead compensation. According to one feature of this apparatus the gain is a function of the algebraic sign of the input signal to the apparatus. Preferably, higher gains are used when the input signal corresponds to wheel deceleration than when it corresponds to acceleration. Another feature of the invention is that the apparatus operates to reduce the magnitude of the lead signal when it exceeds a limit value, preferably by clamping the lead signal to a maximum magnitude. A third feature is that first and second order lead signals are utilized in such a way as to preclude adverse cancellation between the two.

Claims

1. In an antiskid system including a wheel, a brake coupled to the wheel, means for generating a wheel signal indicative of wheel rotation, means responsive to the wheel signal for generating a brake control signal, and means responsive to the brake control signal for reducing braking action of the brake, the improvement comprising:

means for generating a first lead signal as a function of one selected time derivative of the angular velocity of the wheel;

means for generating a second lead signal as a function of another selected time derivative of the angular velocity of the wheel, different from the one selected time derivative, said second lead signal on occasion having a polarity different from that of the first lead signal;

means for generating a composite lead signal as a function of the first and second lead signals, such that the composite lead signal is no less than the greater of the first and second lead signals, even when the polarity of the first lead signal differs from that of the second lead signal; and

means for modifying the brake control signal as a function of the composite lead signal to provide lead compensation.

2. The invention of claim 1 wherein the one selected time derivative is the first time derivative and the other selected time derivative is the second time derivative.

3. The invention of claim 1 wherein the means for generating the composite lead signal is operative to set the composite lead signal to a value proportional to the greater of the first and second lead signals.

4. In an antiskid system including a wheel, a brake coupled to the wheel, means for generating a wheel signal indicative of wheel rotation, means responsive to the wheel signal for generating a brake control signal, and means responsive to the brake control signal for reducing braking action of the brake, the improvement comprising:

means for generating a first lead signal as a function of one selected time derivative of the angular velocity of the wheel;

means for generating a second lead signal as a function of another selected time derivative of the angular velocity of the wheel, different from the one selected time derivative;

means for selecting the one of the first and second lead signals indicative of a greater reduction in braking action;

means for generating a composite lead signal as a function of the selected lead signal to prevent the non-selected lead signal from interfering with the selected lead signal; and

means for modifying the brake control signal as a function of the composite lead signal to provide lead compensation.

5. The invention of claim 4 wherein the composite lead signal is proportional to the selected lead signal.

6. The invention of claim 4 wherein the one selected time derivative is the first time derivative and the other selected time derivative is the second time derivative.

7. In an antiskid system including a wheel, a brake coupled to the wheel, means for generating a wheel signal indicative of wheel rotation, means responsive to the wheel signal for generating a brake control signal as a time integral function of the difference between the angular velocity of the wheel and a threshold velocity, and means responsive to the brake control signal for reducing braking action of the brake, the improvement comprising:

means for generating a first lead signal as a function of a first time derivative of the angular velocity of the wheel;

means for generating a second lead signal as a function of a second time derivative of the angular velocity of the wheel;

means for selecting the one of the first and second lead signals indicative of a greater reduction in braking action;

means for generating a composite lead signal as a function of the selected lead signal to prevent the non-selected lead signal from interfering with the selected lead signal; and

means for modifying the brake control signal as a function of the composite lead signal to provide lead compensation.

8. The invention of claim 7 wherein the composite lead signal is proportional to the selected lead signal.