Apparatus and method for predicting a breaking distance of a vehicle

Abstract

An apparatus and method acquires acceleration data in a time series of a predetermined site of the tire during traveling of the vehicle, and removes an acceleration component due to a deformation of the tire from the acquired acceleration data to obtain a modified acceleration data, and performs frequency analysis of the modified acceleration data to obtain a frequency spectrum, and obtains an accumulated value of the frequency spectrum, and calculating a braking distance parameter for predicting a braking distance based on the obtained accumulated value, and obtains a predicted value of the braking distance of the vehicle based on the braking distance parameter calculated in the calculating part.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a schematic structural view illustrating an example of an apparatus of the present invention;

FIG. 2 is a diagram illustrating a sensor unit and a data processing unit in the apparatus shown in FIG. 1;

FIG. 3 is a flowchart showing an example of a method of the present invention;

FIGS. 4( a) to 4(c) show an example of digitized acceleration data transmitted from the data acquiring part of the sensor unit shown in FIG. 2 and received by a processing part;

FIGS. 5( a) to 5(c) show an example of deformation-component-removed-acceleration data (modified acceleration data) obtained by processing in a signal processing part of the sensor unit shown in FIG. 2;

FIGS. 6( a) to 6(c) show an example of processing results obtained in another embodiment of processing in the signal processing part of the sensor unit shown in FIG. 2;

FIGS. 7( a) to 7(c) show an example of a frequency spectrum obtained in processing in an analyzing part shown in FIG. 2;

FIG. 8 is an example of a scatter diagram representing a correspondence relationship between the braking distance parameter and the braking distance for each case where a particular vehicle is allowed to travel on a road surface under a plurality of different traveling conditions;

FIG. 9 is an example of a scatter diagram representing a correspondence relationship between the braking distance parameter and the braking distance, which shows an example using a value obtained by multiplying the circumferential direction spectrum accumulated value of a tire with a radial direction spectrum accumulated value of the tire as a braking distance parameter; and

FIG. 10 is an example of a scatter diagram representing a correspondence relationship between the braking distance parameter and the braking distance, which shows an example using a width direction spectrum accumulated value of a tire as a braking distance parameter.

Claims

1. An apparatus for predicting a length of a braking distance of a vehicle equipped with tires, while the vehicle is traveling on a road, the braking distance referring to a distance at which the vehicle travels during a period from a commencement of a braking operation for stopping the vehicle to a complete stop of the vehicle, the apparatus including: an acquiring part for acquiring acceleration data in a time series of a predetermined site of the tire during traveling of the vehicle;a removing part for removing an acceleration component due to a deformation of the tire from the acquired acceleration data to obtain a modified acceleration data;an analyzing part for performing frequency analysis of the modified acceleration data to obtain a frequency spectrum;a calculating part for obtaining an accumulated value of the frequency spectrum, and calculating a braking distance parameter for predicting a braking distance based on the obtained accumulated value; anda predicting part for obtaining a predicted value of the braking distance of the vehicle based on the braking distance parameter calculated in the calculating part.

2. The apparatus according to claim 1, further including an acceleration sensor placed on an inner surface of the predetermined site of the tire for measuring the acceleration data.

3. The apparatus according to claim 2, further including a transmitter, the transmitter transmitting the acceleration data measured by the acceleration sensor to the acquiring part by wireless, wherein the acquiring part includes a receiver for receiving the acceleration data transmitted by wireless.

4. The apparatus according to claim 1, further including a storage part for storing a predetermined formula, the predetermined formula representing a correlation between the braking distance of the vehicle and the braking distance parameter; and wherein the predicting part invokes the predetermined formula stored in the storage part, and obtains the predicted value of the braking distance based on the braking distance parameter calculated in the calculating part and the predetermined formula.

5. The apparatus according to claim 4, wherein the predetermined formula is a regression equation representing a correlation between an actually measured value of the braking distance and the braking distance parameter of each of cases where a vehicle equipped with tires of a same specification as that of the tires travels on a road surface under a plurality of different traveling conditions.

6. The apparatus according to claim 1, wherein the acquiring part acquires each of acceleration data in a time series in a plurality of different directions of a predetermined site of the tire, and wherein the removing part removes the acceleration data due to the deformation of the tire from the acceleration data in a time series in each of different directions, andwherein the analyzing part performs frequency analysis of each of the modified acceleration data in the different directions to obtain the frequency spectrum in each of the different directions, andwherein the calculating part obtains each accumulated value of each frequency spectrum in the different directions, and calculates a value obtained by multiplying an accumulated value of the frequency spectrum in each direction as the braking distance parameter.

7. The apparatus according to claim 6, wherein the acquiring part acquires data on an acceleration in a time series in a tire width direction of the tire and acceleration data in a time series in the radial direction of the tire, respectively.

8. The apparatus according to claim 1, wherein the calculating part obtains the accumulated value within a predetermined frequency range among the frequency spectrum obtained in the analyzing part.

9. The apparatus according to claim 1, wherein the acquiring part continuously acquires acceleration data in a time series of a predetermined site of the tire over a unit time defined by a time during which the tire rotates at least two rounds while the vehicle is traveling.

10. The apparatus according to claim 9; wherein the analyzing part performs frequency analysis of the modified acceleration data for each rotation time during which the tire rotates once, thereby obtaining a frequency spectrum for each rotation time; andwherein the calculating part calculates each accumulated value for each rotation time and calculates an average of the accumulated value for each rotation time as the braking distance parameter.

11. The apparatus according to claim 1; wherein the analyzing part divides a region on a circumference of the tire into a first region including a contact portion which takes contact to a road surface and the remaining second region, and performs frequency analysis of the modified acceleration data of the entire first region or only a part of the first region, thereby obtaining a frequency spectrum of the entire first region or the part of the first region.

12. The apparatus according to claim 9; wherein the removing part removes an acceleration component due to the deformation of the tire from the acceleration data in a time series obtained over a unit time defined by a time during which the tire rotates at least two rounds, andwherein the analyzing part performs frequency analysis of the modified acceleration data over a time range during which the tire rotates at least two rounds, thereby obtaining the frequency spectrum.

13. A method of predicting a length of a braking distance of a vehicle equipped with tires, while the vehicle is traveling on a road, the braking distance referring to a distance at which the vehicle travels during a period from a commencement of a braking operation for stopping the vehicle to a complete stop of the vehicle, the method including; an acquiring step for acquiring acceleration data in a time series of a predetermined site of the tire during traveling of the vehicle;a removing step for removing an acceleration component due to a deformation of the tire from the acquired acceleration data to obtain the modified acceleration data;an analyzing step for performing frequency analysis of the modified acceleration to obtain a frequency spectrum;a calculating step for obtaining an accumulated value of the frequency spectrum, and calculating a braking distance parameter for predicting a braking distance based on the obtained accumulated value; anda predicting step for obtaining a predicted value of the braking distance of the vehicle based on the braking distance parameter calculated in the calculating step.

14. The method according to claim 13; in the predicting step, a predetermined formula stored in a storage part be invoked, and the predicted value of the braking distance be obtained based on the braking distance parameter calculated in the calculating part and the formula, and the predetermined formula represent a correlation between the braking distance of the vehicle and the braking distance parameter.

15. The method according to claim 14, wherein the predetermined formula is a regression equation representing a correlation between an actually measured value of the braking distance and the braking distance parameter of each of cases where a vehicle equipped with tires of a same specification as that of the tires travels on a road surface under a plurality of different traveling conditions.