Method, controller and system for monitoring brake operation
First Claim
1. A method of monitoring brake operation on a vehicle comprising:
- receiving a brake demand signal indicative of a brake demand;
receiving at least one stability signal of the vehicle;
receiving a plurality of wheel speed signals from individual wheel speed sensors associated with individual wheel ends of the vehicle;
determining a master value based on the plurality of wheel speed signals over an initiation time period for comparison with the plurality of wheel speed signals;
determining the velocity of the vehicle is equal to or greater than a predetermined minimum velocity;
determining the vehicle is not being controlled by an active safety system;
determining the brake demand signal is greater than a predetermined minimum braking threshold and less than a predetermined maximum braking threshold;
selecting a wheel speed signal having the lowest velocity of the plurality of wheel speed signals when the brake demand is no longer present;
calculating the difference in the selected wheel speed signal from the master value, wherein a predetermined short-term time period has not elapsed;
calculating an integrated difference;
incrementing an error counter by one increment when the integrated difference is greater than a short-term threshold to arrive at an accumulated brake drag count;
determining a brake drag fault exists at the wheel end associated with the selected wheel speed signal when the accumulated brake drag count is greater than an error count threshold and the predetermined short-term time period has not elapsed; and
transmitting a brake control signal at the output to the at least one brake control device to reduce the pressure at the wheel end associated with the brake drag fault.
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Accused Products
Abstract
Various embodiments of an apparatus and method for monitoring a brake operation are disclosed. In accordance with one aspect, the brake operation monitoring system comprises a plurality of wheel speed sensors, a brake demand sensor; a plurality of stability sensors and a controller. The controller comprises wheel speed ports; a brake demand port; stability sensor ports; a communication port for receiving a plurality of messages; and a processing unit comprising control logic. The control logic receives a brake demand signal, at least one stability signal indicative of the cornering of the vehicle, and individual wheel speeds. The control logic calculates a master value to compare to individual wheel speed signals if the brake demand signal indicates no braking.
39 Citations
21 Claims
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1. A method of monitoring brake operation on a vehicle comprising:
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receiving a brake demand signal indicative of a brake demand; receiving at least one stability signal of the vehicle; receiving a plurality of wheel speed signals from individual wheel speed sensors associated with individual wheel ends of the vehicle; determining a master value based on the plurality of wheel speed signals over an initiation time period for comparison with the plurality of wheel speed signals; determining the velocity of the vehicle is equal to or greater than a predetermined minimum velocity; determining the vehicle is not being controlled by an active safety system; determining the brake demand signal is greater than a predetermined minimum braking threshold and less than a predetermined maximum braking threshold; selecting a wheel speed signal having the lowest velocity of the plurality of wheel speed signals when the brake demand is no longer present; calculating the difference in the selected wheel speed signal from the master value, wherein a predetermined short-term time period has not elapsed; calculating an integrated difference; incrementing an error counter by one increment when the integrated difference is greater than a short-term threshold to arrive at an accumulated brake drag count; determining a brake drag fault exists at the wheel end associated with the selected wheel speed signal when the accumulated brake drag count is greater than an error count threshold and the predetermined short-term time period has not elapsed; and transmitting a brake control signal at the output to the at least one brake control device to reduce the pressure at the wheel end associated with the brake drag fault. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A controller for monitoring brake operation of a vehicle comprising:
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a plurality of wheel speed inputs for receiving individual wheel speed sensor signals, each of the plurality of wheel speed inputs correlated with a specific wheel location; a brake demand input; a plurality of stability sensor inputs for receiving stability signals; a communication port for receiving and transmitting a plurality of messages on a serial communications bus; an output for communicating a brake signal to at least one brake control device; and a processing unit comprising control logic, wherein the processing unit is in communication with the plurality of wheel speed inputs and the communication port, the control logic capable of; receiving a brake demand signal indicative of a brake demand; receiving at least one stability signal indicative of the cornering of the vehicle; receiving signals from a plurality of wheel speed signals; determining a master value for comparison with the plurality of wheel speed signals; selecting a wheel speed signal having the lowest velocity of the plurality of wheel speed signals when a brake demand is not present; calculating the difference in the selected wheel speed signal from the master value, wherein a short-term time period has not elapsed; calculating an integrated difference; incrementing an error counter by one increment when the integrated difference is greater than a short-term threshold to arrive at an accumulated brake drag count; determining a brake drag fault exists at the wheel end associated with the selected wheel speed signal when the accumulated brake drag count is greater than an error count threshold and the short-term time period has not elapsed; and transmitting a brake control signal at the output to the at least one brake control device to reduce the pressure at the wheel end associated with the brake drag fault. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A controller for monitoring brake operation of a vehicle comprising:
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control logic, wherein the controller is in communication with a plurality of wheel speed sensors, at least one stability sensor and at least one brake demand sensor, the control logic capable of; receiving a brake demand signal from the at least one brake demand sensor indicative of a brake demand; receiving at least one stability signal from the at least one stability sensor indicative of the cornering of the vehicle; receiving wheel speed sensor signals from the plurality of wheel speed sensors; determining a master value from the plurality of wheel speed signals when the brake demand signal indicates no braking and wherein the at least one stability signal indicates no cornering; calculating a difference of each individual wheel speed signal from the master value when the brake demand signal indicates no braking; calculating an integrated difference of each individual wheel speed signal from the master value; comparing each integrated difference to a short-term drag threshold; incrementing an error counter when the integrated difference of one of the plurality of individual wheel speed signals is greater than the short-term drag threshold; and determining a short-term brake drag fault exists in response to the error counter exceeding a predetermined error count; and controlling at least one brake control device to reduce the pressure at the wheel end associated with the short-term brake drag fault.
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Specification