Tire contact state estimation method

Patent metadata

Field	Value
Publication number	US-10352827-B2
Application number	US-201414889931-A
Country	US
Kind code	B2
Filing date	May 12, 2014
Priority date	Jun 12, 2013
Publication date	Jul 16, 2019
Grant date	Jul 16, 2019

Abstract

A tire contact state estimation method includes: an information acquisition step of acquiring information of the tire; a correlation strength calculation step of calculating a first correlation strength between the rotational velocity and the braking and driving force, and also calculating a second correlation strength between the slip angle and the generated lateral force; a change detection step of detecting whether the first correlation strength has increased or decreased by a first threshold or more with respect to a predetermined first reference value, and also detecting whether the second correlation strength has increased or decreased by a second threshold or more with respect to a predetermined second reference value; and an estimation step of estimating at least two of the following: a condition of a road surface in contact with the tire, a tire internal pressure state, and a tire abrasion state.

First claim

The invention claimed is:

1. A tire contact state estimation method of estimating information on a contact state of a tire mounted on a vehicle to a road surface, the tire contact state estimation method comprising:
an information acquisition step of acquiring information, with a control device, on a rotational velocity from a wheel speed detection device, information on braking and driving force from a wheel braking and driving force detection device, information on a slip angle from a steering angle detection device, and information on generated lateral force of the tire from a steering force detection device;
a correlation strength calculation step of calculating, by the control device, a first correlation strength between the rotational velocity and the braking and driving force from the information on the rotational velocity and the information on the braking and driving force those acquired at the information acquisition step, and also calculating, by the control device, a second correlation strength between the slip angle and the generated lateral force from the information on the slip angle and the information on the generated lateral force those acquired at the information acquisition step;
a change detection step of detecting, by the control device, whether the first correlation strength calculated at the correlation strength calculation step has increased or decreased by a first threshold or more with respect to a predetermined first reference value, and also detecting, by the control device, whether the second correlation strength calculated at the correlation strength calculation step has increased or decreased by a second threshold or more with respect to a predetermined second reference value;
an estimation step of estimating, by the control device based on a result of the detection at the change detection step, at least two of the following: a condition of the road surface in contact with the tire, a tire internal pressure state, and a tire abrasion state; and
a display step of displaying a warning on a display device when an abnormal contact state of the tire to the road surface is detected at the change detection step;
wherein the condition of the road surface in contact with the tire is estimated to have changed from an appropriate road surface to a low-friction road surface when the change detection step detects the first correlation strength having increased by the first threshold or more and the second correlation having decreased by the second threshold or more;
the tire internal pressure state is estimated to have decreased when the change detection step detects the first correlation strength having decreased by the first threshold or more and the second correlation strength having decreased by the second threshold or more; and
the tire abrasion state is estimated to have progressed when the change detection step detects the first correlation strength having decreased by the first threshold or more and the second correlation strength having increased by the second threshold or more.

2. The tire contact state estimation method according to claim 1 , at the change detection step, detecting, by the control device, whether a mean value of the first correlation strength for a predetermined period has increased or decreased by the first threshold or more with respect to the predetermined first reference value and also detecting, by the control device, whether a mean value of the second correlation strength for the predetermined period has increased or decreased by the second threshold or more with respect to the predetermined second reference value, wherein
the predetermined period associated with a result of the detection at the change detection step used to estimate the tire internal pressure state at the estimation step is longer than the predetermined period associated with a result of the detection at the change detection step used to estimate the condition of the road surface in contact with the tire at the estimation step.

3. The tire contact state estimation method according to claim 2 , at the change detection step, detecting, by the control device, whether a mean value of the first correlation strength for a predetermined period has increased or decreased by the first threshold or more with respect to the predetermined first reference value and also detecting, by the control device, whether a mean value of the second correlation strength for the predetermined period has increased or decreased by the second threshold or more with respect to the predetermined second reference value, wherein
the predetermined period associated with a result of the detection at the change detection step used to estimate the tire abrasion state at the estimation step is longer than the predetermined period associated with a result of the detection at the change detection step used to estimate the condition of the road surface in contact with the tire and the tire internal pressure state at the estimation step.

4. The tire contact state estimation method according to claim 1 , at the change detection step, detecting, by the control device, whether a mean value of the first correlation strength for a predetermined period has increased or decreased by the first threshold or more with respect to the predetermined first reference value and also detecting, by the control device, whether a mean value of the second correlation strength for the predetermined period has increased or decreased by the second threshold or more with respect to the predetermined second reference value, wherein
the predetermined period associated with a result of the detection at the change detection step used to estimate the tire abrasion state at the estimation step is longer than the predetermined period associated with a result of the detection at the change detection step used to estimate the condition of the road surface in contact with the tire and the tire internal pressure state at the estimation step.

5. A tire contact state estimation system of estimating information on a contact state of a tire mounted on a vehicle to a road surface, the tire contact state estimation system comprising:
a control device, a wheel speed detection device detecting a rotational velocity of the tire and outputting detection data to the control device, a wheel braking and driving force detection device detecting a braking and driving force of the tire and outputting detection data to the control device, a steering angle detection device detecting a slip angle of the tire and outputting detection data to the control device, a steering force detection device detecting a generated lateral force of the tire and outputting detection data to the control device, and a display device connected to the control device so that, when the control device detects an abnormal contact state of the tire to the road surface, the display device displays a warning,
wherein the control device calculates a first correlation strength between the rotational velocity and the braking and driving force from the information on the rotational velocity of the tire from the input of the wheel speed detection device and the information on the braking and driving force of the tire from the input of the wheel braking and driving force detection device; and
wherein the control device calculates a second correlation strength between the slip angle and the generated lateral force from the information on the slip angle of the tire from the input of the steering angle detection device, and the information on the generated lateral force of the tire from the input of the steering force detection device;
wherein the control device detects whether the first correlation strength calculated at the control device has increased or decreased by a first threshold or more with respect to a predetermined first

Assignees

• Bridgestone Corp

Inventors

• Kato Hiroshi
• Kamikura Takahisa
• Sakurai Ryo
• Hanatsuka Yasushi
• Wakao Yasumichi

Classifications

• B60C23/04

  mounted on the wheel or tyre · CPC title

• G01L17/00

  Devices or apparatus for measuring tyre pressure or the pressure in other inflated bodies · CPC title

• B60T8/172

  Determining control parameters used in the regulation, e.g. by calculations involving measured or detected parameters {(B60T8/17551 takes precedence)} · CPC title

• B60T2210/12

  Friction · CPC title

• B60T2230/02

  Side slip angle, attitude angle, floating angle, drift angle · CPC title