| 摘要 |
Lowpass and highpass filters, having cutoff frequencies different from each other, are used to perform first to fourth filter processing. Then, product-sums of outputs of respective filter processing are obtained. Then, frequencies corresponding to the resonance frequency are obtained based on the result of respective product-sum calculations. The thus obtained frequencies are different from each other in the degree of influence of noise components. Then, among the obtained frequencies, an optimum frequency having less influence of noise components is selected. Then, the selected frequency is smoothed to obtain a resonance frequency for a pneumatic tire pressure estimation.
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