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

Abstract

The vibration of a tireof a running vehicle in the circumferential direction or the width direction is detected by a road surface condition estimating tire, provided with an acceleration sensorand a signal processing unit. 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 mapM, stored in a storage means, 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.