Gyroscope north seeker system and method
First Claim
1. A sensor system for determining a relative direction to true north, comprising:
- at least one angular rate sensor having an input axis and a rotation axis, the angular rate sensor comprising;
a motor drive structure;
a motor signal output from the motor drive structure;
a gyroscope; and
a sensor rate output from the gyroscope for a sensor rate signal;
a frequency divider in operative communication with the motor signal output;
a spinning device coupled to the angular rate sensor;
a spinning device motor coupled to the spinning device and in operative communication with the frequency divider, the spinning device motor having an axis of rotation that is substantially perpendicular to the input axis of the angular rate sensor, the spinning device motor configured to be driven by a periodic signal from the angular rate sensor, wherein a position of the spinning device is synchronized to the periodic signal to generate a spinning device position signal;
a phase detector in operative communication with the spinning device motor and with the sensor rate output;
wherein the relative direction to true north is determined from a phase differential between the spinning device position signal and the sensor rate signal; and
wherein a drive signal for the sensor motor drive structure comes from the angular rate sensor itself without an external drive signal generator.
1 Assignment
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Accused Products
Abstract
A sensor system and method for determining a relative direction to true north is provided. The system comprises at least one angular rate sensor, such as a MEMS sensor, which has an input axis and a rotation axis. The sensor comprises a motor drive structure, a motor signal output from the motor drive structure, a gyroscope, and a sensor rate output from the gyroscope for a sensor rate signal. A frequency divider is in operative communication with the motor signal output, and a spinning device is coupled to the angular rate sensor. A spinning device motor is coupled to the spinning device and is in operative communication with the frequency divider. The spinning device motor has an axis of rotation that is substantially perpendicular to the input axis of the sensor. The spinning device motor is configured to be driven by a periodic signal from the sensor. A position of the spinning device is synchronized to the periodic signal to generate a spinning device position signal. A phase detector is in operative communication with the spinning device motor and with the sensor rate output. The relative direction to true north is determined from a phase differential between the spinning device position signal and the sensor rate signal.
41 Citations
20 Claims
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1. A sensor system for determining a relative direction to true north, comprising:
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at least one angular rate sensor having an input axis and a rotation axis, the angular rate sensor comprising; a motor drive structure; a motor signal output from the motor drive structure; a gyroscope; and a sensor rate output from the gyroscope for a sensor rate signal; a frequency divider in operative communication with the motor signal output; a spinning device coupled to the angular rate sensor; a spinning device motor coupled to the spinning device and in operative communication with the frequency divider, the spinning device motor having an axis of rotation that is substantially perpendicular to the input axis of the angular rate sensor, the spinning device motor configured to be driven by a periodic signal from the angular rate sensor, wherein a position of the spinning device is synchronized to the periodic signal to generate a spinning device position signal; a phase detector in operative communication with the spinning device motor and with the sensor rate output; wherein the relative direction to true north is determined from a phase differential between the spinning device position signal and the sensor rate signal; and wherein a drive signal for the sensor motor drive structure comes from the angular rate sensor itself without an external drive signal generator. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for determining a relative direction to true north, comprising:
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providing at least one MEMS sensor having an input axis and a rotation axis, the input axis substantially perpendicular to the rotation axis, the MEMS sensor comprising a gyroscope and attached to a rotatable table having a table motor; spinning the MEMS sensor about the rotation axis; receiving a physical earth signal at the input axis; directing a sensor rate signal to a phase detector; dividing a periodic drive signal received from the MEMS sensor; directing the divided periodic drive signal to the table motor to drive the table at a given rotation rate, wherein a table rotation rate signal drives modulation of the earth signal onto the input axis; generating a table position signal from the table motor; directing the table position signal to the phase detector; comparing the table position signal to the sensor rate signal to determine a phase differential between the table position signal and the sensor rate signal; and determining an angle to true north based on the phase differential. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A sensor system for determining a relative direction to true north, comprising:
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a MEMS sensor having an input axis and a rotation axis, the MEMS sensor comprising; a motor drive structure; a motor signal output from the motor drive structure; a MEMS gyroscope; and a sensor rate output from the MEMS gyroscope for a sensor rate signal; a frequency divider in operative communication with the motor signal output; a rotatable table coupled to the MEMS sensor; a table motor coupled to the table and in operative communication with the frequency divider, the table motor having an axis of rotation that is substantially perpendicular to the input axis, the table motor configured to be driven by a periodic signal from the MEMS sensor, wherein a position of the table is synchronized to the periodic signal to generate a table position signal; a phase detector in operative communication with the table motor and with the sensor rate output; wherein the relative direction to true north is determined from a phase differential between the table position signal and the sensor rate signal. - View Dependent Claims (20)
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Specification