Navigation apparatus
View Patent ↗A navigation apparatus mounted on a vehicle is equipped with a first gyro sensor and a second gyro sensor arranged in symmetry with respect to a first axis in a travel direction of the vehicle and to a second axis that passes through the center of gravity of the vehicle, the first and second axes being perpendicular to each other, so that the first and second gyro sensors lean by the same angle from the second axis in opposing directions with respect to a third axis that is perpendicular to the first and second axes. A sensor output circuit is connected to each of the first and second gyro sensors, to output an output signal. A calculator calculates a yaw angular velocity of the vehicle based on the output signal.
1. A navigation apparatus mounted on a vehicle having a center of gravity comprising:
a first gyro sensor and a second gyro sensor arranged in symmetry with respect to a first axis in a travel direction of the vehicle and to a second axis that passes through the center of gravity of the vehicle, the first and second axes being perpendicular to each other, so that the first and second gyro sensors lean by the same angle from the second axis in opposing directions with respect to a third axis that is perpendicular to the first and second axes;
a sensor output circuit connected to each of the first and second gyro sensors, to output an output signal; and
a calculator to calculate a yaw angular velocity of the vehicle based on the output signal.
2. The navigation apparatus according to claim 1 , wherein the calculator:
obtains variations X 1 and X 2 in output signals from the first and second gyro sensors, respectively, via the sensor output circuit, as follows:
X 1 = A ×ω×cos(θ−θ1)
X 2 = A ×ω×cos(θ+θ2)
where A is constant, ωis a roll angle of the vehicle, and θ 1 and θ 2 are angles by which the first and second gyro sensors lean from the second axis in the opposing directions, respectively;
obtains a roll angle θ of the vehicle based on the variations X 1 and X 2 as follows:
θ
=
atan
(
(
X
2
×
cos
θ1
-
X
1
×
cos
θ2
)
/
(
X
2
×
sin
θ1
+
X
1
×
sin
θ2
)
)
=
atan
(
(
X
2
-
X
1
)
×
cos
θ0
/
(
(
X
2
+
X
1
)
×
sin
θ0
)
)
where θ 1 =θ 2 =θ 0 , and the sign “atan” means arctangent; and
obtains a yaw angular velocity w of the vehicle based on the variations X 1 and X 2 as follows:
ω
=
sqrt
(
(
X
2
-
X
1
×
cos
(
θ1
+
θ2
)
)
⋀
2
/
(
A
⋀
2
×
sin
(
θ1
+
θ2
)
⋀
2
)
+
X
1
⋀
2
)
/
A
⋀
2
)
=
sqrt
(
(
X
2
-
X
1
×
cos
(
2
×
θ0
)
)
⋀
2
/
(
A
⋀
2
×
sin
(
2
×
θ0
)
⋀
2
)
+
X
1
⋀
2
/
A
⋀
2
)
where the signs “sqrt” and “^2” mean the square root and two squared, respectively.
3. A computer implemented method of calculating a yaw angular velocity of a vehicle comprising the steps of:
obtaining variations X 1 and X 2 in sensor output voltages obtained from a first gyro sensor and a second gyro sensor, respectively:
X 1 = A ×ω×cos(θ−θ1)
X 2 = A ×ω×cos(θ+θ2)
where A is constant and ω is a roll angle of the vehicle, the first and second gyro sensors being arranged in symmetry with respect to a first axis in a travel direction of the vehicle and to a second axis that passes through the center of gravity of the vehicle, the first and second axes being perpendicular to each other, so that the first and second gyro sensors lean by the same lean angles θ 1 and θ 2 respectively, from the second axis in opposing directions with respect to a third axis that is perpendicular to the first and second axes;
obtaining a roll angle e of the vehicle based on the variations X 1 and X 2 as follows:
θ
=
atan
(
(
X
2
×
cos
θ1
-
X
1
×
cos
θ2
)
/
(
X
2
×
sin
θ1
+
X
1
×
sin
θ2
)
)
=
atan
(
(
X
2
-
X
1
)
×
cos
θ0
/
(
(
X
2
+
X
1
)
×
sin
θ0
)
)
where θ 1 =θ 2 =θ , and the sign “atan” means arctangent; and
obtaining a yaw angular velocity ω of the vehicle based on the variations X 1 and X 2 as follows:
ω
=
sqrt
(
(
X
2
-
X
1
×
cos
(
θ1
+
θ2
)
)
⋀
2
/
(
A
⋀
2
×
sin
(
θ1
+
θ2
)
⋀
2
)
+
X
1
⋀
2
)
/
A
⋀
2
)
=
sqrt
(
(
X
2
-
X
1
×
cos
(
2
×
θ0
)
)
⋀
2
/
(
A
⋀
2
×
sin
(
2
×
θ0
)
⋀
2
)
+
X
1
⋀
2
/
A
⋀
2
)
where the signs “sqrt” and “^2” mean the square root and two squared, respectively.