Method and apparatus for detecting a tire inflation pressure
First Claim
1. A method for detecting a tire inflation pressure of a vehicle tire, comprising the steps of:
- producing an oscillating electric signal having a vibration frequency component of said vehicle tire;
transforming the oscillating electric signal by a wavelet function into a wavelet coefficient, said wavelet function being provided on the basis of a mother wavelet function localized in time, scaled in response to a scale parameter, and shifted in response to a shift parameter indicative of a time localization;
extracting a resonance frequency from the vibration frequency component of said vehicle tire on the basis of the wavelet coefficient, the step of extracting the resonance frequency including extracting a maximum frequency from the vibration frequency components of said vehicle tire obtained every first predetermined time period on the basis of the wavelet coefficient, and selecting a most frequent value of the maximum frequencies extracted in a second predetermined time period thereby to set the most frequent value for the resonance frequency; and
estimating the tire inflation pressure on the basis of the resonance frequency.
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Accused Products
Abstract
The invention is directed to a method and apparatus for detecting a tire inflation pressure of a vehicle tire. The apparatus includes a device for producing an oscillating electric signal having a vibration frequency component of the vehicle tire. A wavelet transformer transforms the oscillating electric signal by a wavelet function into a wavelet coefficient. The wavelet function is provided on the basis of a mother wavelet function localized in time, scaled in response to a scale parameter, and shifted in response to a shift parameter indicative of a time localization. Then, an extracting device extracts a resonance frequency from the vibration frequency component of the vehicle tire on the basis of the wavelet coefficient, and an estimating device estimates the tire inflation pressure on the basis of the resonance frequency. The apparatus may further include a warning device for warning a decrease of the tire inflation pressure when the resonance frequency decreases to an extent that a difference between the resonance frequency and the reference frequency exceeds a predetermined frequency.
28 Citations
8 Claims
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1. A method for detecting a tire inflation pressure of a vehicle tire, comprising the steps of:
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producing an oscillating electric signal having a vibration frequency component of said vehicle tire; transforming the oscillating electric signal by a wavelet function into a wavelet coefficient, said wavelet function being provided on the basis of a mother wavelet function localized in time, scaled in response to a scale parameter, and shifted in response to a shift parameter indicative of a time localization; extracting a resonance frequency from the vibration frequency component of said vehicle tire on the basis of the wavelet coefficient, the step of extracting the resonance frequency including extracting a maximum frequency from the vibration frequency components of said vehicle tire obtained every first predetermined time period on the basis of the wavelet coefficient, and selecting a most frequent value of the maximum frequencies extracted in a second predetermined time period thereby to set the most frequent value for the resonance frequency; and estimating the tire inflation pressure on the basis of the resonance frequency. - View Dependent Claims (2, 3, 7)
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4. An apparatus for detecting a tire inflation pressure of a vehicle tire, comprising:
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means for producing an oscillating electric signal having a vibration frequency component of said vehicle tire; means for transforming the oscillating electric signal by a wavelet function into a wavelet coefficient, said wavelet function being provided on the basis of a mother wavelet function localized in time, scaled in response to a scale parameter, and shifted in response to a shift parameter indicative of a time localization; means for extracting a resonance frequency from the vibration frequency component of said vehicle tire on the basis of the wavelet coefficient, said means for extracting the resonance frequency including means for extracting a maximum frequency from the vibration frequency components of said vehicle tire obtained every first predetermined time period on the basis of the wavelet coefficient obtained by said means for transforming the oscillating electric signal into the wavelet coefficient, and means for selecting a most frequent value of the maximum frequencies extracted in a second predetermined time period thereby to set the most frequent value for the resonance frequency; and means for estimating the tire inflation pressure on the basis of the resonance frequency. - View Dependent Claims (5, 6, 8)
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Specification