Anti-lock brake yaw control method
First Claim
1. A method of operation for a braking system for rear wheels of a vehicle including a driver-activated brake pedal and an ABS system effective when activated to modulate a rear brake pressure supplied to rear wheel brakes of the vehicle based on target slip and deceleration values for reducing yaw moments due to braking on split or uneven coefficient of friction road surfaces, the method comprising the steps of:
- determining a measure of braking intensity;
determining a difference in slip or deceleration between the rear wheels;
defining a yaw entry threshold having a nominal value that is reduced in proportion to the measure of braking intensity; and
activating said ABS system for modulating the rear brake pressure based on said target slip and deceleration values when the determined difference in slip or deceleration exceeds the yaw entry threshold.
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Accused Products
Abstract
An improved anti-lock rear brake yaw control method utilizes a measure of braking intensity to regulate both the initiation of yaw control and the anti-lock braking control parameters once yaw control is initiated. The brake torque and the rate of brake pedal depression provide measures of braking intensity, and are used to develop variable slip and deceleration thresholds to which the rear wheel differential slip and deceleration are compared. The variable thresholds permit initiation of yaw control at relatively low levels of differential wheel slip or deceleration during panic braking, while requiring higher levels of differential wheel slip or deceleration to initiate yaw control during moderate braking. Once yaw control is initiated, the slip and deceleration thresholds are utilized to adaptively adjust the slip and deceleration targets, so that the targets are set in accordance with the slip and deceleration of the rear wheel with the lowest coefficient of friction during panic braking, and at higher levels during moderate braking.
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Citations
10 Claims
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1. A method of operation for a braking system for rear wheels of a vehicle including a driver-activated brake pedal and an ABS system effective when activated to modulate a rear brake pressure supplied to rear wheel brakes of the vehicle based on target slip and deceleration values for reducing yaw moments due to braking on split or uneven coefficient of friction road surfaces, the method comprising the steps of:
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determining a measure of braking intensity;
determining a difference in slip or deceleration between the rear wheels;
defining a yaw entry threshold having a nominal value that is reduced in proportion to the measure of braking intensity; and
activating said ABS system for modulating the rear brake pressure based on said target slip and deceleration values when the determined difference in slip or deceleration exceeds the yaw entry threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of operation for a braking system for rear wheels of a vehicle including a driver-activated brake pedal and an ABS system effective when activated to modulate a rear brake pressure supplied to rear wheel brakes of the vehicle based on target slip and target deceleration values for reducing yaw moments due to braking on split or uneven coefficient of friction road surfaces, the method comprising the steps of:
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determining a measure of braking intensity;
determining a difference in slip and a difference in deceleration between said rear wheels;
defining slip and deceleration thresholds, each having a nominal value that is reduced in proportion to the measure of braking intensity; and
measuring slip and deceleration values of the rear wheels;
determining the target slip value based on the highest of the measured slip values, reduced by said slip threshold; and
determining the target deceleration value based on the highest of the measured deceleration values, reduced by said deceleration threshold. - View Dependent Claims (9, 10)
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Specification