US 5,490,072 AGranted

Method and system for detecting the proper functioning of an ABS control unit utilizing dual programmed microprocessors

AssigneeKelsey-Hayes Company

InventorEdward R. Hornback

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Abstract

A method and apparatus for detecting the proper functioning of an ABS control unit which utilizes dual programmed microprocessors, the second of which calculates mismatched wheel speed and both of which calculate extended control loop time. When computed wheel velocities are above 10 mph, the second microprocessor determines whether the difference in computed wheel velocity between the two microprocessors is at least 2 mph. If the difference is more than 2 mph for more than 6 consecutive program loops, a mismatched wheel speed calculation error is identified. Each of the microprocessors also compares its loop timing with the loop timing of the other microprocessor and if more than 1 millisecond late for 6 consecutive program loops, the proper diagnostic response is to set an ignition latch code which triggers an inhibit signal. In addition, if the first microprocessor determines more than a 16 millisecond delay, then the first microprocessor is reset. If the second microprocessor determines more than a 65 millisecond delay, then the second microprocessor is reset.

Claims16

Dependent claims

In a vehicle anti-lock brake system (ABS), a method for detecting the proper functioning of an ABS control unit having first and second microprocessors, the first microprocessor being programmed with a first program to operate on a first program loop and the second microprocessor being programmed with a second program to operate on a second program loop, the method comprising the steps of:

a) generating wheel speed signals based on angular speed of each wheel of the vehicle;
b) processing the wheel speed signals to obtain a digital representation for each of the wheel speed signals;
c) utilizing the first programmed microprocessor to calculate a first wheel speed during the first program loop based on the digital representation for a particular wheel;
d) utilizing the second programmed microprocessor to calculate a second wheel speed during the second program loop also based on the digital representation for the particular wheel;
e) utilizing the second programmed microprocessor to subtract the first and second wheels speeds to obtain a difference value, and to compare the difference value with a first predetermined value;
f) repeating steps a)-e) as long as the difference value is greater than the first predetermined value in a first predetermined number of consecutive program loops of the second programmed microprocessor;
and
g) utilizing the second programmed microprocessor to generate a first output inhibit signal upon repeating steps a)-e) in the first predetermined number of consecutive program loops wherein the first output inhibit signal prevents the ABS control unit from issuing an erroneous brake control signal.

5 more elements

In a vehicle anti-lock brake system (ABS), apparatus for detecting the proper functioning of an ABS control unit, the apparatus comprising:

means for generating wheel speed signals based on angular speed of each wheel of the vehicle;
means for processing the wheel speed signals to obtain a digital representation for each of the wheel speed signals;
a first microprocessor programmed with a first program to operate on a first program loop to calculate a first wheel speed during the first program loop based on the digital representation for a particular wheel;
a second microprocessor programmed with a second program to operate on a second program loop to calculate a second wheel speed during the second program loop also based on the digital representation for the particular wheel, wherein the second programmed microprocessor is programmed to subtract the first and second wheels speeds to obtain a difference value and to compare the difference value with a first predetermined value, and wherein if the difference value is greater than the first predetermined value for a first predetermined number of consecutive program loops, the second programmed microprocessor generates a first output inhibit signal wherein the first output inhibit signal prevents the ABS control unit from issuing an erroneous brake control signal.

1 more element

Dependencies are inferred from the claim text.