Road gradient estimating system
First Claim
1. A road gradient estimating system comprising:
- a first portion for calculating a first physical amount “
Ggrad0”
corresponding to an estimated gradient value of a road on which a vehicle is currently traveling, based on a difference between an acceleration “
A”
detected by an acceleration sensor for detecting acceleration of the vehicle in a vehicle longitudinal direction and an acceleration “
A′
”
of the vehicle with respect to the road;
a second portion for storing data for relation between vehicle speed and a second physical amount corresponding to a limiting value for rate-of-change of road gradient;
a third portion, to which information of vehicle speed is inputted, for calculating a third physical amount (α
up, α
down) corresponding to the limiting value for rate-of-change of road gradient at the inputted vehicle speed, based on the relation between the vehicle speed and the second physical amount stored in the second portion; and
a fourth portion for comparing rate-of-change of the first physical amount “
Ggrad0”
corresponding to the estimated gradient value with the third physical amount (α
up, α
down) corresponding to the limiting value for the rate-of-change of road gradient calculated at the third portion,wherein the fourth portion corrects the first physical amount “
Ggrad0”
corresponding to the estimated gradient value, in such a manner that the first physical amount “
Ggrad0”
corresponding to the estimated gradient value is limited to the limiting value for the rate-of-change of road gradient calculated at the third portion, when the rate-of-change of the first physical amount “
Ggrad0”
corresponding to the estimated gradient value is larger than the third physical amount (α
up, α
down) corresponding to the limiting value for the rate-of-change of road gradient calculated at the third portion.
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Accused Products
Abstract
An estimated gradient value of a road is calculated based on a vehicle acceleration “A” and a time varying portion “A′” of a wheel speed. In a case that an acceleration corresponding value “Ggrad0” for the estimated gradient value is not regarded as indicating an exact figure, due to influences of disturbances, the acceleration corresponding value “Ggrad0” is corrected by a limiting value for rate-of-change with regard to the road gradient depending on respective vehicle speed, and by a limiting value for the road gradient. As a result, the acceleration corresponding value “Ggrad” for the estimated gradient value can be more exactly obtained.
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Citations
14 Claims
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1. A road gradient estimating system comprising:
-
a first portion for calculating a first physical amount “
Ggrad0”
corresponding to an estimated gradient value of a road on which a vehicle is currently traveling, based on a difference between an acceleration “
A”
detected by an acceleration sensor for detecting acceleration of the vehicle in a vehicle longitudinal direction and an acceleration “
A′
”
of the vehicle with respect to the road;a second portion for storing data for relation between vehicle speed and a second physical amount corresponding to a limiting value for rate-of-change of road gradient; a third portion, to which information of vehicle speed is inputted, for calculating a third physical amount (α
up, α
down) corresponding to the limiting value for rate-of-change of road gradient at the inputted vehicle speed, based on the relation between the vehicle speed and the second physical amount stored in the second portion; anda fourth portion for comparing rate-of-change of the first physical amount “
Ggrad0”
corresponding to the estimated gradient value with the third physical amount (α
up, α
down) corresponding to the limiting value for the rate-of-change of road gradient calculated at the third portion,wherein the fourth portion corrects the first physical amount “
Ggrad0”
corresponding to the estimated gradient value, in such a manner that the first physical amount “
Ggrad0”
corresponding to the estimated gradient value is limited to the limiting value for the rate-of-change of road gradient calculated at the third portion, when the rate-of-change of the first physical amount “
Ggrad0”
corresponding to the estimated gradient value is larger than the third physical amount (α
up, α
down) corresponding to the limiting value for the rate-of-change of road gradient calculated at the third portion. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A road gradient estimating system comprising:
-
a vehicle speed sensor mounted on a vehicle for detecting vehicle speed; a first acceleration sensor mounted on the vehicle for detecting a first vehicle acceleration “
A”
in a vehicle longitudinal direction;a second acceleration sensor mounted on the vehicle for detecting a second vehicle acceleration “
A′
”
with respect to a road, on which the vehicle is currently traveling; andan electronic control unit for periodically calculating road gradient in each calculating cycle, based on the vehicle speed and the first and second vehicle accelerations “
A” and
“
A′
”
,wherein the electronic control unit comprises; a road gradient calculating portion for calculating an acceleration corresponding value “
Ggrad0”
for estimated gradient value, based on a difference between the first vehicle acceleration “
A” and
the second vehicle acceleration “
A′
;a first-limiting-value calculating portion for receiving information for detected vehicle speed from the vehicle speed sensor, and having a first map for relation between the vehicle speed and a limiting value for rate-of-change of road gradient, the first-limiting-value calculating portion calculating a first limiting value (α
up, α
down) corresponding to the detected vehicle speed based on the first map;a first comparing portion for comparing the acceleration corresponding value “
Ggrad0”
with a first upper limit “
Grad1(previous cycle)+α
up” and
with a first lower limit “
Grad1(previous cycle)−
α
down”
in order to correct the acceleration corresponding value “
Ggrad0”
to produce a first corrected value “
Ggrad1”
, wherein the first upper limit “
Grad1(previous cycle)+α
up” and
the first lower limit “
Grad1(previous cycle)−
α
down”
are calculated based on the first limiting value (α
up, α
down),wherein the first upper limit “
Grad1(previous cycle)+α
up”
is produced as the first corrected value “
Ggrad1”
, in the case that the acceleration corresponding value “
Ggrad0”
is larger than the first upper limit “
Grad1(previous cycle)+α
up”
,wherein the acceleration corresponding value “
Ggrad0”
is produced as the first corrected value “
Ggrad1”
, in the case that the acceleration corresponding value “
Ggrad0”
is smaller than the first upper limit “
Grad1(previous cycle)+α
up”
but larger than the first lower limit “
Grad1(previous cycle)−
α
down”
, andwherein the first lower limit “
Grad1(previous cycle)−
α
down”
is produced as the first corrected value “
Ggrad1”
, in the case that the acceleration corresponding value “
Ggrad0”
is smaller than the first lower limit “
Grad1(previous cycle)−
α
down”
. - View Dependent Claims (11, 12)
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13. A road gradient estimating system comprising:
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a vehicle speed sensor mounted on a vehicle for detecting vehicle speed; a first acceleration sensor mounted on the vehicle for detecting a first vehicle acceleration “
A”
in a vehicle longitudinal direction;a second acceleration sensor mounted on the vehicle for detecting a second vehicle acceleration “
A′
”
with respect to a road, on which the vehicle is currently traveling;a navigation system mounted on the vehicle for memorizing information of legal speed for respective roads; and an electronic control unit for periodically calculating road gradient in each calculating cycle, based on the vehicle speed and the first and second vehicle accelerations “
A” and
“
A′
”
,wherein the electronic control unit comprises; a road gradient calculating portion for calculating an acceleration corresponding value “
Ggrad0”
for estimated gradient value, based on a difference between the first vehicle acceleration “
A” and
the second vehicle acceleration “
A′
;a first-limiting-value calculating portion for receiving the information of the legal speed from the navigation system and information for detected vehicle speed from the vehicle speed sensor, and having a first map for relation between the legal speed and a curvature radius of the road for a current position of the vehicle, in order to calculate a first limiting value (α
up, α
down) for rate-of-change of road gradient based on the detected vehicle speed and the curvature radius obtained from the first map;a first comparing portion for comparing the acceleration corresponding value “
Ggrad0”
with a first upper limit “
Grad1(previous cycle)+α
up” and
with a first lower limit “
Grad1(previous cycle)−
α
down”
in order to correct the acceleration corresponding value “
Ggrad0”
to produce a first corrected value “
Ggrad1”
, wherein the first upper limit “
Grad1(previous cycle)+α
up” and
the first lower limit “
Grad1(previous cycle)−
α
down”
are calculated based on the first limiting value (α
up, α
down),wherein the first upper limit “
Grad1(previous cycle)+α
up”
is produced as the first corrected value “
Ggrad1”
, in the case that the acceleration corresponding value “
Ggrad0”
is larger than the first upper limit “
Grad1(previous cycle)+α
up”
,wherein the acceleration corresponding value “
Ggrad0”
is produced as the first corrected value “
Ggrad1”
, in the case that the acceleration corresponding value “
Ggrad0”
is smaller than the first upper limit “
Grad1(previous cycle)+α
up”
but larger than the first lower limit “
Grad1(previous cycle)−
α
down”
, andwherein the first lower limit “
Grad1(previous cycle)−
α
down”
is produced as the first corrected value “
Ggrad1”
, in the case that the acceleration corresponding value “
Ggrad0”
is smaller than the first lower limit “
Grad1(previous cycle)−
α
down”
. - View Dependent Claims (14)
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Specification