ROAD SURFACE CONDITION ESTIMATING METHOD, VEHICLE CONTROL METHOD, AND ROAD SURFACE CONDITION ESTIMATING APPARATUS

• US 20120296493A1
• Filed: 05/15/2012
• Published: 11/22/2012
• Est. Priority Date: 05/16/2011
• Status: Active Grant

• Current Assignee: Bridgestone Corporation
• Original Assignee: Bridgestone Corporation
• Inventors: WAKAO, Yasumichi
• Granted Patent: US 9,045,117 B2
• Time in Patent Office: Days
• US Class Current: 701/1
• CPC Class Codes: B60C 11/1369 Tie bars for linking block elements and bridging the groove
• CPC Class Codes: B60C 2019/004 Tyre sensors other than for detecting tyre pressure
• CPC Class Codes: B60T 2210/12 Friction
• CPC Class Codes: B60T 8/172 Determining control parameters used in the regulation, e.g. by calculations involving measured or detected parameters B60T8/17551 takes precedence
• CPC Class Codes: B60W 2050/0057 Frequency analysis, spectral techniques or transforms
• CPC Class Codes: B60W 2422/10 on a suspension arm
• CPC Class Codes: B60W 2422/70 on the wheel or the tire
• CPC Class Codes: B60W 2520/28 Wheel speed
• CPC Class Codes: B60W 40/06 Road conditions
• CPC Class Codes: B60W 40/064 Degree of grip
• CPC Class Codes: B60W 40/068 Road friction coefficient

Abstract

The condition of a road surface on which a vehicle is traveling is estimated accurately, using a tire having a general variable-pitch tire pattern for detection of a road surface condition. The tire for detection of a road surface condition has rows of blocks, the total number N of the circumferentially disposed blocks being 10 or more and the number n of lug grooves, each provided with a joining section connecting circumferentially adjacent blocks, being in the range of (N/2)≦n≦(N−5). The vibrations of the tire are detected by an acceleration sensor and are subjected to a rotational order ratio analysis by a rotational order ratio analyzing unit. And the road surface condition is estimated by comparing the amplitude P of the rotational order component of the tire vibrations extracted by a rotational order component extracting unit with a predetermined threshold value K.

Claims

1. A method for estimating a road surface condition,

comprising the steps of:

detecting vibrations of a tire having a block pattern;

performing a rotational order ratio analysis on the tire vibrations; and

estimating a current road surface condition from an amplitude of a rotational order component of the analyzed tire vibrations,

wherein the tire has at least one row of blocks, the total number N of the circumferentially disposed blocks being 10 or more,

wherein the row of blocks has the number n of lug grooves, each provided with a joining section connecting circumferentially adjacent blocks, n being in the range of (N/2)≦

n≦

(N−

5), and

wherein the order of the rotational order component for estimation of the road surface condition is (N−

n).

2. The method for estimating a road surface condition according to claim 1, wherein the height of the joining section from the bottom of the lug groove is equal to or less than the height of the block, and the axial length of the joining section is equal to or less than ½

of the width of the block or equal to or less than the depth of the lug groove.

3. The method for estimating a road surface condition according to claim 1, wherein the row of blocks is formed in the central area of a tire tread.

4. The method for estimating a road surface condition according to claim 1, wherein the vibrations of the tire are detected in an unsprung portion of a vehicle.

5. A vehicle control method, comprising:

controlling the traveling performance of a vehicle based on a road surface condition estimated by claim 1.

6. An apparatus for estimating a road surface condition,

comprising:

a tire for estimation of a road surface condition, the tire having at least one row of blocks, the total number N of the circumferentially disposed blocks being 10 or more, the row of blocks having the number n of lug grooves, each provided with a joining section connecting circumferentially adjacent blocks, n being in the range of (N/2)≦

n≦

(N−

5);

a vibrations detecting unit disposed in an unsprung portion of a vehicle for detecting vibrations of a tire tread propagated to the unsprung portion from the tire;

a rotational order components extracting unit for performing a rotational order ratio analysis on the vibrations of the tire tread detected by the vibrations detecting unit and extracting the amplitude of a rotational order component whose order is (N−

n); and

a road surface condition estimating unit for estimating a current road surface condition from the extracted amplitude of the rotational order component.