Navigation system and a vehicle including the navigation system
A navigation system includes a Coriolis vibratory gyroscope, a voltage input supply, and a controller. The voltage input supply is configured to supply a first voltage input to the Coriolis vibratory gyroscope at a first bias voltage, and supply a second voltage input to the Coriolis vibratory gyroscope at a second bias voltage, the second bias voltage being different than the first bias voltage. The controller is configured to detect a difference in responses of the Coriolis vibratory gyroscope to the first bias voltage and the second bias voltage, and determine a gyro rate of the Coriolis vibratory gyroscope as a function of the difference in responses and a correction term.
1. A navigation system comprising:
a Coriolis vibratory gyroscope;
a voltage input supply configured to
supply a first voltage input to the Coriolis vibratory gyroscope at a first bias voltage, and
supply a second voltage input to the Coriolis vibratory gyroscope at a second bias voltage, the second bias voltage being different than the first bias voltage; and
a controller configured to detect a difference in responses of the Coriolis vibratory gyroscope to the first bias voltage and the second bias voltage, and determine a gyro rate of the Coriolis vibratory gyroscope as a function of the difference in responses and a correction term.
2. The navigation system of claim 1 , wherein the Coriolis vibratory gyroscope outputs a first response in response to the first bias voltage and a second response in response to the second bias voltage and the correction term represents a sum of the time dependent instrument bias in the first response and the second response.
3. The navigation system of claim 1 , wherein the controller is configured to determine the gyro rate of the Coriolis vibratory gyroscope independent of a scale factor of the Coriolis vibratory gyroscope.
4. The navigation system of claim 1 , wherein the correction term is a predetermined constant value based on an initial voltage output and initial input rate of the Coriolis vibratory gyroscope at the first bias voltage and the second bias voltage.
5. The navigation system of claim 1 , wherein a change in voltage output of the Coriolis vibratory gyroscope from a first response at the first bias voltage to a second response at the second bias voltage provides a first scale factor corresponding to the first response and a second scale factor corresponding to the second response for a common voltage input to the Coriolis vibratory gyroscope.
6. The navigation system of claim 5 , wherein the gyro rate (Ω) is determined from the equation
Ω
=
(
V
0
-
V
0
′
-
C
)
1
S
0
-
1
S
0
′
where S 0 is the first scale factor and S 0 ′ is the second scale factor with (1/S 0 )−(1/S 0 ′) being the difference in responses of the Coriolis vibratory gyroscope to the first bias voltage and the second bias voltage, V 0 is the first response at the first bias voltage, V 0 ′ is the second response at the second bias voltage, and C is the correction term.
7. The navigation system of claim 6 , wherein the difference in responses of the Coriolis vibratory gyroscope to the first bias voltage and the second bias voltage is constant.
8. The navigation system of claim 5 , wherein the controller is configured to continue to determine the gyro rate of the Coriolis vibratory gyroscope, as the function of the difference in responses and the correction term, independent of calibration of the first scale factor and calibration of the second scale factor where the time dependent instrument bias causes the first scale factor and the second scale factor to shift equally.
9. The navigation of claim 1 , wherein the controller is configured to navigate a vehicle from a first location to a second location with the Coriolis vibratory gyroscope.
10. A vehicle comprising:
a navigation system including
a Coriolis vibratory gyroscope;
a voltage input supply configured to
supply a first voltage input to the Coriolis vibratory gyroscope at a first bias voltage, and
supply a second voltage input to the Coriolis vibratory gyroscope at a second bias voltage, the second bias voltage being different than the first bias voltage;
a controller configured to detect a difference in responses of the Coriolis vibratory gyroscope to the first bias voltage and the second bias voltage, and determine a gyro rate of the Coriolis vibratory gyroscope as a function of the difference in responses and a correction term.
11. The vehicle of claim 10 , wherein the Coriolis vibratory gyroscope outputs a first response in response to the first bias voltage and a second response in response to the second bias voltage and the correction term represents a sum of the time dependent instrument bias in the first response and the second response.
12. The vehicle of claim 10 , wherein the controller is configured to determine the gyro rate of the Coriolis vibratory gyroscope independent of a scale factor of the Coriolis vibratory gyroscope.
13. The vehicle of claim 10 , wherein the correction term is a predetermined constant value based on an initial voltage output and initial input rate of the Coriolis vibratory gyroscope at the first bias voltage and the second bias voltage.
14. The vehicle of claim 10 , wherein a change in voltage output of the Coriolis vibratory gyroscope from a first response at the first bias voltage to a second response at the second bias voltage provides a first scale factor corresponding to the first response and a second scale factor corresponding to the second response for a common voltage input to the Coriolis vibratory gyroscope.
15. The vehicle of claim 14 , wherein the gyro rate (Ω) is determined from the equation
Ω
=
(
V
0
-
V
0
′
-
C
)
1
S
0
-
1
S
0
′
where S 0 is the first scale factor and S 0 ′ is the second scale factor with (1/S 0 )−(1/S 0 ′) being the difference in responses of the Coriolis vibratory gyroscope to the first bias voltage and the second bias voltage, V 0 is the first response at the first bias voltage, V 0 ′ is the second response at the second bias voltage, and C is the correction term.
16. The vehicle of claim 15 , wherein the difference in responses of the Coriolis vibratory gyroscope to the first bias voltage and the second bias voltage is constant.
17. The vehicle of claim 14 , wherein the controller is configured to continue to determine the gyro rate of the Coriolis vibratory gyroscope, as the function of the difference in responses and the correction term, independent of calibration of the first scale factor and calibration of the second scale factor where the time dependent instrument bias causes the first scale factor and the second scale factor to shift equally.
18. The vehicle of claim 10 , wherein the controller is configured to navigate the vehicle from a first location to a second location with the Coriolis vibratory gyroscope.
19. The vehicle of claim 10 , wherein the vehicle comprises one of an aerospace vehicle, a maritime vehicle, an automotive vehicle, an amphibious vehicle or any other suitable vehicle.
20. The vehicle of claim 10 , wherein the vehicle comprises a consumer electronics vehicle.