| 摘要 |
PROBLEM TO BE SOLVED: To provide a tire pneumatic pressure sensor which makes it possible to accurately sense the tire resonance frequency with high reliability by suppressing the influence of noise given to the tire resonance frequency calculation by a gravitational center method as much as possible. SOLUTION: An ECU(electronic control unit) 5 calculates the wheel speed from the detected results of wheel speed sensors 2a to 2d corresponding to tires 1a to 1d of a vehicle. The ECU 5 discriminates whether the noise generating frequency calculated based on the wheel speed falls within a gravitational center method applying range or not, and reserves the calculated result of an FET(fast Fourier transformation) at each zone divided in response to the wheel speed within the range if the noise generating frequency falls within the method applying range. The FET calculated result of the same number is extracted in each zone of the wheel speed, and averaged for the extracted calculated result. At this time, the noise component included in the FET calculated result is averaged in the applying range, and the influence of the noise is removed. Further, the resonance frequency of the tire is calculated by the method for the averaged frequency waveform.
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