Method for determining the coefficient of friction between a vehicle tire and a roadway
First Claim
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1. A mehod for determining the coefficient of friction between a vehicle tire and a roadway comprising:
- (a) pressurizing during normal brake operation one of the vehicle wheels at a higher brake pressure than another wheel,(b) comparing the rotational speed of said one wheel with the rotational speed of the other wheel for determining the wheel slip of said one wheel from the difference in the rotational speeds of the other wheel and said one wheel when the pressure on said one wheel reaches a value indicative of a predetermined braking torque on said one wheel;
(c) measuring the axle load on said one wheel; and
(d) determining the coefficient of friction between the tire of said one wheel and said roadway from said measured axle load, said predetermined braking torque, and the inverse proportion of said determined wheel slip.
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Abstract
In a method for determining the coefficient of friction between a vehicle tire and a roadway one of the vehicle wheel is pressurized during normal brake operation at a higher pressure than another wheel. The rotational speed of the braked wheel is compared with the rotational speed of another non-braked wheel for determining the wheel slip. Furthermore, the axle load of the braked wheel is measured. On the basis of wheel slip, brake torque and axle load, the coefficient of friction is determined.
58 Citations
18 Claims
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1. A mehod for determining the coefficient of friction between a vehicle tire and a roadway comprising:
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(a) pressurizing during normal brake operation one of the vehicle wheels at a higher brake pressure than another wheel, (b) comparing the rotational speed of said one wheel with the rotational speed of the other wheel for determining the wheel slip of said one wheel from the difference in the rotational speeds of the other wheel and said one wheel when the pressure on said one wheel reaches a value indicative of a predetermined braking torque on said one wheel; (c) measuring the axle load on said one wheel; and (d) determining the coefficient of friction between the tire of said one wheel and said roadway from said measured axle load, said predetermined braking torque, and the inverse proportion of said determined wheel slip. - View Dependent Claims (2, 3, 4, 6, 10, 11, 12, 13, 14, 15, 16, 17)
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5. A method for determining the coefficient of friction between a vehicle tire and a roadway comprising:
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(a) pressurizing during normal brake operation one of the vehicle wheels at a higher brake pressure than another; (b) comparing the rotational speed of said one wheel with the rotational speed of the other wheel for determining the wheel slip of said one wheel from the difference in the rotational speeds of the other wheel and said one wheel; (c) terminating the pressurizing of said one wheel when said determined wheel slip of said one wheel reaches a predetermined value; (d) measuring the brake pressure indicative of a braking torque at the time when said predetermined wheel slip is reached; (e) measuring the axle load of said one wheel; (f) determining the coefficient of friction between the tire of said one wheel and said roadway from said measured axle load, said measured brake pressure and said predetermined wheel slip. - View Dependent Claims (7, 8, 9)
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18. A method of determining the coefficient of friction between a tire on one wheel of a vehicle and a roadway, the wheels of said vehicle being braked by pressurized fluid, comprising:
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(a) pressurizing the brake of said one wheel to a greater extent than another brake of another wheel; (b) at a predetermined pressure measuring the speed of said one wheel relative to said other; (c) determining the slip of said one wheel from the difference in the rotational speeds of said one and said other wheels; (d) measuring the axle load on said one wheel; and (e) calculating the actual coefficient of friction between a tire of said one wheel and the roadway from the measured axle load and the inverse proportion of the determined slip of said one wheel.
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Specification