US 8,577,540 B2 · Method and apparatus for detecting tire having decreased internal pressure, and program for detecting tire having decreased internal pressure

Abstract

A method for detecting a tire having a decreased internal pressure by making a relative comparison of wheel speeds of tires. The method includes a step of detecting wheel rotation information of the respective tires of the vehicle; a step of calculating wheel speeds based on the detected wheel rotation information; a step of calculating a decreased pressure determination value; and a step of determining a tire having a decreased internal pressure. The method further comprises a step of setting a threshold value, in which the predetermined threshold value is set based on a decreased pressure sensitivity calculated from a relation between a load sensitivity and a decreased pressure sensitivity during vehicle turning with regard to tires that is calculated in advance and a load sensitivity obtained through a turning running during initialization.

Claims10

Dependent claims

A method for detecting a tire having a decreased internal pressure by making a relative comparison of wheel speeds of tires attached to the respective wheels of a vehicle, comprising the steps of:

detecting wheel rotation information of the respective tires of the vehicle;
calculating, using a Central Processing Unit (CPU), wheel speeds based on the detected wheel rotation information;
calculating a decreased pressure determination value by making a relative comparison of the calculated wheel speeds;
and
determining a tire having a decreased internal pressure when the resultant decreased pressure determination value exceeds a predetermined threshold value,
wherein the method further comprises a step of setting a threshold value, in which the predetermined threshold value is set, during initialization, based on a decreased pressure sensitivity calculated from a relation between a load sensitivity and a decreased pressure sensitivity during vehicle turning that is calculated in advance in a calibration phase and a load sensitivity obtained through a turning running during initialization, and
wherein the load sensitivity is calculated based on a relational expression between a ratio of the dynamic loaded radius change due to the load shift during turning to the dynamic loaded radius, the ratio being calculated based on a yaw rate and a lateral acceleration obtained from a yaw rate sensor and a lateral acceleration sensor mounted in the vehicle and wheel speeds of left and right wheels of the vehicle, and a lateral acceleration.

4 more elements

An apparatus for detecting a tire having a decreased internal pressure, comprising:

a wheel rotation information detection device configured to detect wheel rotation information of the respective tires of the vehicle;
and
a control unit arranged and configured to
calculate wheel speeds based on the wheel rotation information detected by the wheel rotation information detection device;
calculate a decreased pressure determination value by a relative comparison of the calculated wheel speeds;
and
determine, when the resultant decreased pressure determination value exceeds a predetermined threshold value, a tire having a decreased internal pressure,
wherein the control unit is arranged and configured to set the predetermined threshold value, during initialization, based on a decreased pressure sensitivity calculated from a relation between a load sensitivity and a decreased pressure sensitivity during vehicle turning that is calculated in advance in a calibration phase and a load sensitivity obtained through a turning running during initialization, and
wherein the control unit is arranged and configured to calculate the load sensitivity based on a relational expression between a ratio of the dynamic loaded radius change due to the load shift during turning to the dynamic loaded radius, the ratio being calculated based on a yaw rate and a lateral acceleration obtained from a yaw rate sensor and a lateral acceleration sensor mounted in the vehicle and wheel speeds of left and right wheels of the vehicle, and a lateral acceleration.

6 more elements

A method for detecting a tire having a decreased internal pressure by making a relative comparison of wheel speeds of tires attached to the respective wheels of a front-wheel drive vehicle or a rear-wheel drive vehicle, comprising the steps of:

detecting wheel rotation information of the respective tires of the vehicle;
calculating, using a Central Processing Unit (CPU), wheel speeds based on the detected wheel rotation information;
calculating a decreased pressure determination value by making a relative comparison of the calculated wheel speeds;
and
determining a tire having a decreased internal pressure when the resultant decreased pressure determination value exceeds a predetermined threshold value,
wherein the method further comprises a step of setting a threshold value, in which the predetermined threshold value is set, during initialization, based on a decreased pressure sensitivity calculated from a relation between a load sensitivity and a decreased pressure sensitivity during vehicle turning that is calculated in advance in a calibration phase and a load sensitivity obtained through a turning running during initialization, and
wherein the load sensitivity is estimated by comparison between change amounts of dynamic loaded radii of left and right driven wheels during vehicle turning obtained from the wheel speeds and change amounts of dynamic loaded radii of left and right driving wheels during vehicle turning obtained from the wheel speeds, and is a regression coefficient obtained by the following formula, provided that ωR and ωL are wheel speeds of right and left wheels of the driven wheel (idler) and the driving wheel (drive):
Y=AX1+BX2+CX3,
wherein,
Y
=
[
(
ω
⁢
⁢
R
-
ω
⁢
⁢
L
)
(
ω
⁢
⁢
R
+
ω
⁢
⁢
L
)
]
drive
-
[
(
ω
⁢
⁢
R
-
ω
⁢
⁢
L
)
(
ω
⁢
⁢
R
+
ω
⁢
⁢
L
)
]
idler
,
⁢
X
1
=
(
ω
⁢
⁢
R
+
ω
⁢
⁢
L
)
2
⁢
(
[
(
ω
⁢
⁢
R
-
ω
⁢
⁢
L
)
(
ω
⁢
⁢
R
+
ω
⁢
⁢
L
)
]
drive
-
[
(
ω
⁢
⁢
R
-
ω
⁢
⁢
L
)
(
ω
⁢
⁢
R
+
ω
⁢
⁢
L
)
]
idler
)
,
⁢
X
2
=
(
ω
⁢
⁢
R
+
ω
⁢
⁢
L
)
⁢
(
ω
⁢
⁢
R
-
ω
⁢
⁢
L
)
,
and
X
3
=
(
(
ω
⁢
⁢
R
+
ω
⁢
⁢
L
)
t
-
(
ω
⁢
⁢
R
+
ω
⁢
⁢
L
)
t
-
1
Δ
⁢
⁢
t
)
⁢
(
ω
⁢
⁢
R
+
ω
⁢
⁢
L
)
⁢
(
ω
⁢
⁢
R
+
ω
⁢
⁢
L
)
.

221 more elements

An apparatus for detecting a tire having a decreased internal pressure by making a relative comparison of wheel speeds of tires attached to the respective wheels of a front-wheel drive vehicle or a rear-wheel drive vehicle, the apparatus comprising:

a wheel rotation information detection device configured to detect wheel rotation information of the respective tires of the vehicle;
and
a control unit arranged and configured to
calculate wheel speeds based on the detected wheel rotation information detected by the wheel rotation information detection device;
calculate a decreased pressure determination value by making a relative comparison of the calculated wheel speeds;
and
determine a tire having a decreased internal pressure when the resultant decreased pressure determination value exceeds a predetermined threshold value,
wherein the control unit is arranged and configured to set a threshold value, in which the predetermined threshold value is set, during initialization, based on a decreased pressure sensitivity calculated from a relation between a load sensitivity and a decreased pressure sensitivity during vehicle turning that is calculated in advance in a calibration phase and a load sensitivity obtained through a turning running during initialization, and
wherein the control unit is arranged and configured to estimate the load sensitivity by comparison between change amounts of dynamic loaded radii of left and right driven wheels during vehicle turning obtained from the wheel speeds and change amounts of dynamic loaded radii of left and right driving wheels during vehicle turning obtained from the wheel speeds, and is a regression coefficient obtained by the following formula, provided that ωR and ωL are wheel speeds of right and left wheels of the driven wheel (idler) and the driving wheel (drive):
Y=AX1+BX2+CX3,
wherein,
Y
=
[
(
ω
⁢
⁢
R
-
ω
⁢
⁢
L
)
(
ω
⁢
⁢
R
+
ω
⁢
⁢
L
)
]
drive
-
[
(
ω
⁢
⁢
R
-
ω
⁢
⁢
L
)
(
ω
⁢
⁢
R
+
ω
⁢
⁢
L
)
]
idler
,
⁢
X
1
=
(
ω
⁢
⁢
R
+
ω
⁢
⁢
L
)
2
⁢
(
[
(
ω
⁢
⁢
R
-
ω
⁢
⁢
L
)
(
ω
⁢
⁢
R
+
ω
⁢
⁢
L
)
]
drive
-
[
(
ω
⁢
⁢
R
-
ω
⁢
⁢
L
)
(
ω
⁢
⁢
R
+
ω
⁢
⁢
L
)
]
idler
)
,
⁢
X
2
=
(
ω
⁢
⁢
R
+
ω
⁢
⁢
L
)
⁢
(
ω
⁢
⁢
R
-
ω
⁢
⁢
L
)
,
and
X
3
=
(
(
ω
⁢
⁢
R
+
ω
⁢
⁢
L
)
t
-
(
ω
⁢
⁢
R
+
ω
⁢
⁢
L
)
t
-
1
Δ
⁢
⁢
t
)
⁢
(
ω
⁢
⁢
R
+
ω
⁢
⁢
L
)
⁢
(
ω
⁢
⁢
R
+
ω
⁢
⁢
L
)
.

223 more elements

A computer program product for detecting a tire having a decreased internal pressure by making a relative comparison of wheel speeds of tires attached to the respective wheels of a front-wheel drive vehicle or a rear-wheel drive vehicle, the computer program product comprising at least one non-transitory computer-readable storage medium having computer-executable program instructions stored therein, the computer-executable program instructions comprising:

calculating wheel speeds based on the detected wheel rotation information of respective tires of a vehicle;
calculating a decreased pressure determination value by making a relative comparison of the calculated wheel speeds;
determining a tire having a decreased internal pressure when the resultant decreased pressure determination value exceeds a predetermined threshold value;
and
setting the predetermined threshold value, during initialization, based on a decreased pressure sensitivity calculated from a relation between a load sensitivity and a decreased pressure sensitivity during vehicle turning that is calculated in advance in a calibration phase and a load sensitivity obtained through a turning running during initialization,
wherein the load sensitivity is estimated by comparison between change amounts of dynamic loaded radii of left and right driven wheels during vehicle turning obtained from the wheel speeds and change amounts of dynamic loaded radii of left and right driving wheels during vehicle turning obtained from the wheel speeds, and is a regression coefficient obtained by the following formula, provided that ωR and ωL are wheel speeds of right and left wheels of the driven wheel (idler) and the driving wheel (drive):
Y=AX1+BX2+CX3,
wherein,
Y
=
[
(
ω
⁢
⁢
R
-
ω
⁢
⁢
L
)
(
ω
⁢
⁢
R
+
ω
⁢
⁢
L
)
]
drive
-
[
(
ω
⁢
⁢
R
-
ω
⁢
⁢
L
)
(
ω
⁢
⁢
R
+
ω
⁢
⁢
L
)
]
idler
,
⁢
X
1
=
(
ω
⁢
⁢
R
+
ω
⁢
⁢
L
)
2
⁢
(
[
(
ω
⁢
⁢
R
-
ω
⁢
⁢
L
)
(
ω
⁢
⁢
R
+
ω
⁢
⁢
L
)
]
drive
-
[
(
ω
⁢
⁢
R
-
ω
⁢
⁢
L
)
(
ω
⁢
⁢
R
+
ω
⁢
⁢
L
)
]
idler
)
,
⁢
X
2
=
(
ω
⁢
⁢
R
+
ω
⁢
⁢
L
)
⁢
(
ω
⁢
⁢
R
-
ω
⁢
⁢
L
)
,
and
X
3
=
(
(
ω
⁢
⁢
R
+
ω
⁢
⁢
L
)
t
-
(
ω
⁢
⁢
R
+
ω
⁢
⁢
L
)
t
-
1
Δ
⁢
⁢
t
)
⁢
(
ω
⁢
⁢
R
+
ω
⁢
⁢
L
)
⁢
(
ω
⁢
⁢
R
+
ω
⁢
⁢
L
)
.

220 more elements

Dependencies are inferred from the claim text.

Method and apparatus for detecting tire having decreased internal pressure, and program for detecting tire having decreased internal pressure

Life of this patent

Method and apparatus for detecting tire having decreased internal pressure, and program for detecting tire having decreased internal pressure

Life of this patent

Abstract

Claims10