Rear wheel anti-lock brake controller
First Claim
Patent Images
1. A wheel lock control method for a vehicle having left and right rear wheels for transporting the vehicle over a roadway having varying coefficients of friction, each wheel having a brake responsive to a brake pressure for braking the wheel, the method comprising the steps of:
- measuring the speeds ω
r and ω
l of the rear wheels;
sensing an incipient lockup condition of either of the rear wheels;
increasing a value of a rear wheel reference speed toward ω
r at a predetermined rate when ω
r is less than ω
l ;
increasing the value of the rear wheel reference speed toward ω
l at a predetermined rate when ω
l is less than ω
r ; and
modulating the brake pressure to the brakes of the rear wheels when an incipient lockup condition of one of the rear wheels is sensed based upon the value of the rear wheel reference speed so as to prevent a wheel lockup condition.
1 Assignment
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Accused Products
Abstract
A rear wheel speed reference utilized in an anti-lock brake controller as the basis for controlling the rear wheel brakes of a vehicle controlled by a common control signal is established based on the road surface condition. When the vehicle is being braked on a split coefficient of friction surface, the rear wheel speed reference is established at the wheel speed which is the lowest between the two wheels. This provides braking in accord with a select low mode of operation. However, when the two rear wheels are being braked on a uniform surface, the rear wheel speeds are processed such that an average of the two wheel speeds is provided as the rear wheel speed reference for establishing the braking control signal for the rear wheels.
22 Citations
4 Claims
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1. A wheel lock control method for a vehicle having left and right rear wheels for transporting the vehicle over a roadway having varying coefficients of friction, each wheel having a brake responsive to a brake pressure for braking the wheel, the method comprising the steps of:
-
measuring the speeds ω
r and ω
l of the rear wheels;sensing an incipient lockup condition of either of the rear wheels; increasing a value of a rear wheel reference speed toward ω
r at a predetermined rate when ω
r is less than ω
l ;increasing the value of the rear wheel reference speed toward ω
l at a predetermined rate when ω
l is less than ω
r ; andmodulating the brake pressure to the brakes of the rear wheels when an incipient lockup condition of one of the rear wheels is sensed based upon the value of the rear wheel reference speed so as to prevent a wheel lockup condition.
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2. A wheel lock control method for a vehicle having a pair of rear wheels for transporting the vehicle over a roadway having varying coefficients of friction, each wheel having a brake responsive to a brake pressure for braking the wheel, the method comprising the steps of:
-
measuring the speeds ω
lr and ω
rl of the rear wheels;sensing an incipient lockup condition of either of the rear wheels; setting a parameter S equal to (A) 1 when the measured speed ω
lr is lower than the measured speed ω
rl and (B) 0 when the measured speed ω
rl is lower than the measured speed ω
lr ;filtering the parameter S; determining a rear wheel reference speed equal to Kω
lr +(1-K)ω
rl where K is the filtered parameter S;modulating the brake pressure to the brakes of the rear wheels when an incipient lockup condition of one of the rear wheels is sensed based upon the value of the rear wheel reference speed so as to prevent an incipient wheel lockup condition. - View Dependent Claims (3)
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4. A wheel lock control method for a vehicle having a pair of rear wheels for transporting the vehicle over a roadway having varying coefficients of friction, each wheel having a brake responsive to a brake pressure for braking the wheel, the method comprising the steps of:
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measuring the speeds ω
lr and ω
rl of the rear wheels;determining a hypothetical wheel speed of an unbraked wheel of the vehicle; determining an optimum wheel slip value λ
opt ;sensing an incipient lockup condition of either of the rear wheels; setting a parameter S equal to (A) 1 when the measured speed ω
lr is lower than the measured speed ω
rl and (B) 0 when the measured speed ω
rl is lower than the measured speed ω
lr ;filtering the parameter S; determining a rear wheel reference speed equal to Kω
lr +(1-K)ω
rl where K is the filtered parameter S;determining a value of wheel slip based on the determined rear wheel reference speed and the hypothetical wheel speed; and modulating the brake pressure to the brakes of the rear wheels to a common pressure when an incipient lockup condition of one of the rear wheels is sensed so as to maintain the determined value of wheel slip substantially at the determined optimum wheel slip value.
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Specification
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Current AssigneeGeneral Motors Corporation (Motors Liquidation Co. GUC Trust)
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Original AssigneeGeneral Motors Corporation (Motors Liquidation Co. GUC Trust)
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InventorsLin, William C.
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Primary Examiner(s)Lall, Parshotam S.
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Assistant Examiner(s)NOT, DEFINED
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Application NumberUS07/430,033Time in Patent Office461 DaysField of Search364/426.02, 364/426.03, 303/96, 303/100, 303/106, 303/109, 303/95, 303/102, 303/103, 180/197, 361/238US Class Current701/73CPC Class CodesB60T 8/1764 Regulation during travel on...B60T 8/4266 having an electro-mechanica...
