Road surface condition estimating method, road surface condition estimating tire, road surface condition estimating apparatus, and vehicle control apparatus

摘要

The vibration of a tire 10 of a running vehicle in the circumferential direction or the width direction is detected by a road surface condition estimating tire 10, provided with an acceleration sensor 11 and a signal processing unit 12. Data of a detected vibration waveform are divided into data of three domains, namely, a pre-leading domain, a contact patch domain, and a post-trailing domain, and then the vibration levels in the pre-leading domain and the contact patch domain, respectively, are extracted. At the same time, a vibration component in a low-frequency band and a vibration component in a high-frequency band are extracted respectively from the vibration levels in the respective domains, and respective vibration level ratios R, which are each a ratio thereof, are calculated. Then, on the vehicle body side, the condition of a road surface on which the vehicle is running is estimated, based on the calculated vibration level ratio R and a map 32M, stored in a storage means 32, showing a relationship between the vibration level ratio R of tire vibration and road surface conditions. Thus a road surface condition can be estimated with accuracy even when there are changes in temperature or vehicle speed.

主权项

1. A road surface condition estimating apparatus comprising:
a reception means for receiving the wirelessly transmitted data of a vibration level or a vibration level computed value from a road surface condition estimating tire; and a road surface condition estimating means for estimating a road surface condition based on the vibration level or the vibration level computed value; and the road surface condition estimating tire comprising: a tire vibration detecting means disposed on the air chamber side of an inner liner in a tire tread area, the tire vibration detecting means detecting the vibration of a tire of a running vehicle; a pre-trailing domain signal extracting means for extracting signals of the pre-trailing domain, which is a domain before a trailing position estimated from a peak position of said tire vibration detected by said tire vibration detecting means; a post-trailing domain signal extracting means for extracting signals of tire vibration in the post-trailing domain, which is a domain after the trailing position estimated from the peak position of said tire vibration detected by said tire vibration detecting means; a frequency analysis means for analyzing the frequencies of said signals extracted by the pre-trailing domain signal extracting means and signals extracted by the post-trailing domain signal extracting means and obtaining a frequency spectrum in the pre-trailing domain and a frequency spectrum in the post-trailing domain; a vibration level calculating means for calculating a vibration level of a frequency band, the lower-limit frequency of which being 0.5 kHz or above and the upper-limit frequency of which being 4 kHz or below, from the obtained frequency spectrum of the post-trailing domain obtained by the frequency analysis means, and a vibration level of a frequency band, the lower-limit frequency of which being 2 kHz or above and the upper-limit frequency of which being 10 kHz or below, from a frequency spectrum of the pre-trailing domain obtained thereby; a means for calculating a vibration level computed value using said calculated vibration level in the post-trailing domain and vibration level in the pre-trailing domain; a means for wirelessly and automatically transmitting data of the vibration level or vibration level computed value to the vehicle body side; and a transmission means for wirelessly and automatically transmitting information of the estimated road surface condition to another vehicle automatically, wherein the frequency band for calculating the vibration level is higher in pre-trailing domain than the band in the post-trailing domain.