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

• US 9,046,457 B2
• Filed: 06/19/2006
• Issued: 06/02/2015
• Est. Priority Date: 06/17/2005
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Bridgestone
• Original Assignee: Kabushiki Kaisha Bridgestone
• Inventors: Morinaga, Hiroshi, Hanatsuka, Yasushi
• Primary Examiner(s): Mawari, Redhwan K
• Assistant Examiner(s): King, Rodney P
• Application Number:
  US11/917,852
• Publication Number:
  US 20090105921A1
• Time in Patent Office: 3,270 Days
• Field of Search: 701/80, 731/46
• US Class Current: 1/1
• CPC Class Codes: B60G 17/0165 to an external condition, e.g. rough road surface, side wind
• CPC Class Codes: B60G 2204/113 Tyre related sensors
• CPC Class Codes: B60G 2400/206 Body oscillation speed; Body vibration frequency
• CPC Class Codes: B60G 2400/252 vertical
• CPC Class Codes: B60G 2400/821 Uneven, rough road sensing affecting vehicle body vibration
• CPC Class Codes: B60G 2600/70 Computer memory; Data storage, e.g. maps for adaptive control
• CPC Class Codes: B60G 2800/162 Reducing road induced vibrations
• CPC Class Codes: B60G 2800/702 Improving accuracy of a sensor signal
• CPC Class Codes: B60G 2800/916 Body Vibration Control
• CPC Class Codes: B60T 2210/12 Friction
• CPC Class Codes: B60T 8/1725 Using tyre sensors, e.g. Sidewall Torsion sensors [SWT] for tyre pressure and temperature detection B60C23/00
• CPC Class Codes: B60W 2422/70 on the wheel or the tire
• CPC Class Codes: B60W 2552/35 Road bumpiness, e.g. potholes
• CPC Class Codes: B60W 40/06 Road conditions
• CPC Class Codes: G01N 19/02 Measuring coefficient of friction between materials testing of tyres G01M17/02; determinations of friction coefficient used in vehicle braking or traction control systems B60T8/172

Abstract

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.

Claims

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.

3. The road surface condition estimating apparatus according to claim 1 or 2, further comprising:

a reception means for automatically receiving the wirelessly transmitted information on a road surface condition; and

a means for automatically grasping a road surface condition ahead from information on a road surface condition automatically transmitted from a vehicle running ahead.

2. A road surface condition estimating apparatus comprising:

a reception means for receiving the wirelessly transmitted data of vibration level or 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, said 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 a pre-trailing domain, which is a domain before the 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 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 band-pass filter for extracting a signal in the post-trailing domain, whose lower-limit frequency of which being 0.5 kHz or above and upper-limit frequency of which being 4 kHz or below out of the signal in the post-trailing domain, and a signal in the pre-trailing domain, whose lower-limit frequency of which being 2 kHz or above and upper-limit frequency of which being 10 kHz or below out of the signal in the pre-trailing domain by inputting said signals of the post-trailing domain extracted by the post-trailing domain signal extracting means and signals of the pre-trailing domain extracted by the pre-trailing domain signal extracting means;

a vibration level calculating means for calculating a vibration level which is the vibration level of the signal in the post-trailing domain and a vibration level which is the vibration level of the signal in the pre-trailing domain, which are extracted by the band-pass filter;

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; and

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,

wherein the frequency band for calculating the vibration level is higher in pre-trailing domain than the band in the post-trailing domain.