Apparatus and method for presuming condition of road surface
First Claim
1. An apparatus for presuming a condition of road surface comprising:
- rotational speed detecting means for periodically detecting rotational speeds of four tires of a vehicle;
first computing means for computing a slip ratio from measurement values of the rotational speed detecting means;
second computing means for obtaining a relational formula between the slip ratio and acceleration/deceleration of the vehicle; and
friction coefficient judging means for judging a coefficient of friction occurring between a road and a tire on the basis of a slope of the relational formula obtained by the second computing means.
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Abstract
An apparatus for presuming a condition of road surface comprising: rotational speed detecting means for periodically detecting rotational speeds of four tires of a vehicle; first computing means for computing a slip ratio from measurement values of the rotational speed detecting means; second computing means for obtaining a relational formula between the slip ratio and acceleration/deceleration of the vehicle; and friction coefficient judging means for judging a coefficient of friction occurring between a road and a tire on the basis of a slope of the relational formula obtained by the second computing means. The road friction coefficient μ can be judged with high accuracy in short time by using only the wheel rotational speed information of four wheels. Thus, the performance and safety of a vehicle can be increased.
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Citations
9 Claims
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1. An apparatus for presuming a condition of road surface comprising:
- rotational speed detecting means for periodically detecting rotational speeds of four tires of a vehicle;
first computing means for computing a slip ratio from measurement values of the rotational speed detecting means;
second computing means for obtaining a relational formula between the slip ratio and acceleration/deceleration of the vehicle; and
friction coefficient judging means for judging a coefficient of friction occurring between a road and a tire on the basis of a slope of the relational formula obtained by the second computing means.
- rotational speed detecting means for periodically detecting rotational speeds of four tires of a vehicle;
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2. A method for presuming a condition of road surface comprising the steps of:
- periodically detecting rotational speeds of four tires of a vehicle;
computing a slip ratio from the measured rotational speeds;
obtaining a relational formula between the slip ratio and acceleration/deceleration of the vehicle;
comparing a slope of the relational formula with a preset threshold; and
judging a coefficient of friction occurring between a road and a tire from a result of the comparison. - View Dependent Claims (3, 4, 5, 6)
- periodically detecting rotational speeds of four tires of a vehicle;
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7. An apparatus for presuming a condition of road surface comprising:
- rotational speed detecting means for periodically detecting rotational speeds of four tires of a vehicle;
first computing means for computing acceleration/deceleration of the vehicle and a slip ratio of tires from measurement values of the rotational speed detecting means;
moving-average calculating means for calculating a moving average from the acceleration/deceleration of the vehicle and the slip ratio in predetermined time;
weighted moving-average calculating means for performing moving average on the moving average value obtained by the moving-average calculating means;
second computing means for obtaining a relational formula between the acceleration/deceleration of the vehicle and the slip ratio from weighted moving averages obtained by the weighted moving average calculating means; and
friction coefficient judging means for judging a coefficient of friction occurring between a road and a tire on the basis of a slope of the relational formula obtained by the second computing means.
- rotational speed detecting means for periodically detecting rotational speeds of four tires of a vehicle;
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8. A method for presuming a condition of road surface comprising the steps of:
- periodically detecting rotational speeds of four tires of a vehicle;
computing acceleration/deceleration of the vehicle and a slip ratio of tires from the measured rotational speed;
calculating a moving average of the acceleration/deceleration of the vehicle and the slip ratio in predetermined time;
performing moving average on the moving average value obtained in the moving average calculating step;
obtaining a relational formula between the acceleration/deceleration of the vehicle and the slip ratio from the weighted moving averages obtained by the weighted moving average calculating means;
comparing a slope of the relational formula with a preset threshold; and
judging a coefficient of friction occurring between a road and a tire from a result of the comparison. - View Dependent Claims (9)
- periodically detecting rotational speeds of four tires of a vehicle;
Specification