Measuring method and measuring apparatus to detect charge potential between tire and road surface

• US 9,772,361 B2
• Filed: 12/26/2012
• Issued: 09/26/2017
• Est. Priority Date: 12/26/2011
• Status: Active Grant

• Current Assignee: Bridgestone Corporation, University of Tokyo
• Original Assignee: Bridgestone Corporation, University of Tokyo
• Inventors: Takiguchi, Kiyoaki, Suda, Yoshihiro, Yamabe, Shigeyuki, Kouno, Kenji, Hayashi, Tatsuo, Yamada, Kotaro, Masaki, Nobuo
• Primary Examiner(s): Lee, Paul D
• Application Number:
  US14/368,357
• Publication Number:
  US 20140350879A1
• Time in Patent Office: 1,735 Days
• Field of Search: 702 70
• CPC Class Codes: B60T 2210/12 Friction
• CPC Class Codes: B60T 8/172 Determining control parameters used in the regulation, e.g. by calculations involving measured or detected parameters B60T8/17551 takes precedence
• CPC Class Codes: G01L 17/00 Devices or apparatus for measuring tyre pressure or the pressure in other inflated bodies
• CPC Class Codes: G01M 17/02 Tyres
• CPC Class Codes: G01N 19/02 Measuring coefficient of friction between materials testing of tyres G01M17/02; determinations of friction coefficient used in vehicle braking or traction control systems B60T8/172
• CPC Class Codes: G01N 27/221 by investigating the dielectric properties using microwaves G01N22/00; measuring loss factors or dielectric constants per se G01R27/26
• CPC Class Codes: G01N 27/60 by investigating electrostatic variables , e.g. electrographic flaw testing G01N27/007 takes precedence
• CPC Class Codes: G01R 29/12 Measuring electrostatic fields or voltage-potential
• CPC Class Codes: G01R 29/24 Arrangements for measuring quantities of charge

Abstract

A charge potential distributed over a vehicle body resulting from the contact, separation, and friction between a tire and a road surface is detected by a detecting unit provided with a sensing electrode that is disposed on the external surface of the vehicle body, a reference electrode that is disposed apart from the external surface of the vehicle body with a space therebetween, and a sensor amplifier that senses a potential between the sensing electrode and the reference electrode as a signal and amplifies the signal. And the amplitude of the charge potential detected by the detecting unit is monitored by a data processing unit, thereby making it possible to accurately identify not only the state of the road surface but also an internal pressure state of the tire, a wear state of the tire, and the like during vehicular travel.

Claims

1. A measuring method, comprising:

disposing a first electrode on a vehicle body and a second electrode spaced apart from the first electrode;

detecting a charge potential between the first electrode and the second electrode, the charge potential distributed over the vehicle body or a tire resulting from contact, separation, and friction between a tire and a road surface;

monitoring an amplitude of the charge potential detected in the detecting;

counting plural times a number of specific peaks in each unit period, which is a number of peaks of variation in charge potential occurring in a time-varying waveform of the amplitude larger than a mean of the amplitude in each unit period; and

determining a state of the road surface under the tire or detecting at least one condition of the tire including an internal pressure state, a wear state, or vibration characteristics of the tire from a frequency of occurrences of the specific peaks.

2. The measuring method according to claim 1, further comprising extracting a time-varying waveform of the amplitude and estimating a state of road surface under the tire from a change in the time-varying waveform of the amplitude changing with changes in the state of the road surface.

3. The measuring method according to claim 1, further comprising extracting a time-varying waveform of the amplitude and detecting an internal pressure state of the tire from a change in the time-varying waveform of the amplitude changing with changes in the internal pressure of the tire.

4. The measuring method according to claim 1, further comprising extracting a time-varying waveform of the amplitude and detecting a wear state of the tire from a change in the time-varying waveform of the amplitude changing with changes in the wear state of the tire.

5. The measuring method according to claim 1, further comprising extracting a time-varying waveform of the amplitude and detecting vibration characteristics of the tire from a change in the time-varying waveform of the amplitude changing with changes in the vibration characteristics of the tire.

6. The measuring method according to claim 1, wherein the counting comprises obtaining an RMS value in a unit period from the time-varying waveform of the amplitude as a mean of the amplitude in the unit period.

7. The measuring method according to claim 6, wherein the counting comprises extracting a positive-side peak and a negative-side peak from the time-varying waveform of the amplitude, calculating a peak value difference, which is the difference between the amplitude value of the positive-side peak and the amplitude value of the negative-side peak, determining the positive-side peak or the negative-side peak as a specific peak when the peak value difference exceeds the RMS value, and counting the number of specific peaks thus determined, and wherein the estimating or detecting comprises finding a frequency distribution of the numbers of specific peaks in a unit period and estimating a state of road surface under the tire or detecting an internal pressure state, a wear state, or vibration characteristics of the tire from the frequency of specific peak occurrences.

8. The measuring method according to claim 7, wherein the estimating or detecting comprises calculating a scale parameter and a shape parameter of probability density function of a Weibull distribution by approximating the frequency distribution by the Weibull distribution and estimating a state of road surface under the tire or detecting an internal pressure state, a wear state, or vibration characteristics of the tire from the calculated scale parameter and shape parameter or from the calculated shape parameter.

9. The measuring method according to claim 1, wherein the first electrode includes a sensing electrode and the second electrode includes a reference electrode.

10. The measuring method according to claim 1 further comprising providing a sensor amplifier to detect the charge potential and to amplify a signal of the charge potential.

11. A measuring apparatus comprising:

a first electrode disposed on a vehicle body;

a second electrode spaced apart from the first electrode;

a detecting unit configured to detect charge potential between the first electrode and the second electrode, the charge potential distributed over the vehicle body or a tire resulting from contact, separation, and friction between a tire and a road surface; and

a monitoring unit configured to monitor an amplitude of the charge potential detected by the detecting unit and to count plural times a number of specific peaks in each unit period, which is a number of peaks of variation in charge potential occurring in a time-varying waveform of amplitude larger than a mean of amplitude in each unit period, thereby the monitoring unit determining a state of the road surface under the tire or detecting an internal pressure state, a wear state, or vibration characteristics of the tire from a frequency of specific peak occurrences.

12. The measuring apparatus according to claim 11, wherein the first electrode includes a sensing electrode and the second electrode includes a reference electrode.

13. The measuring apparatus according to claim 11 further comprising a sensor amplifier configured to detect the charge potential and to amplify a signal of the charge potential.