Adaptive inertial measurement system and method

1. A control system, comprising:

a processor that adjusts at least one of an automatic gain control (AGC) loop, an offset loop, and a phase modulator scale factor loop based on environmental conditions for an inertial measurement unit (IMU), wherein a gain of the AGC loop is adjusted by the processor in accordance with a digital gain factor and an analog gain factor, wherein the analog gain factor is increased and the digital gain factor is decreased during low dynamic conditions, or the analog gain factor is decreased and the digital gain factor is increased during high dynamic conditions, wherein each of the at least one of the AGC loop, the offset loop, and the phase modulator scale loop operates over a range of set points defined for each respective control loop.

2. The control system of claim 1 , further comprising a dynamic loop adjuster that:

receives environmental input data;

determines the environmental conditions for the IMU based on the received environmental input data; and

issues a set point adjustment command to the processor to adjust at least one of the set points for at least one of the AGC loop, the offset loop, and the phase modulator scale factor loop based on the determined environmental conditions.

3. The control system of claim 2 , further comprising an interface that receives the environmental input data as external data from a remote data source from the IMU.

4. The control system of claim 3 , wherein the external data includes information relating to a vibration event, a shock event, a pressure change event, a humidity change event, or a temperature change event for the IMU.

5. The control system of claim 1 , further comprising a sensing circuit to sense the environmental conditions of the IMU.

6. The control system of claim 5 , wherein the sensing circuit includes at least one of an accelerometer sensor on the IMU, a vibration sensor on the IMU, a temperature sensor on the IMU, and an output value from an analog circuit monitoring the one or more control loops of the processor.

7. The control system of claim 1 , further comprising:

a fiber optic gyroscope (FOG) circuit that generates a modulated optical signal representing angular motion for the IMU;

an optical receiver to convert the modulated output signal from the FOG to an electrical signal representing the angular motion of the IMU; and

an analog-to-digital (A/D) converter to convert the electrical signal from the optical receiver to a digital signal for the processor, wherein the processor employs the AGC loop to control an electrical signal gain of the optical receiver, employs the offset control loop to control electrical offsets in one or more circuits of the IMU, and the phase modulator scale factor loop to track sensitivity information of the modulated optical signal from the FOG.

8. The control system of claim 7 , further comprising a dynamic auxiliary control loop operated by the processor that slows down output data changes or holds data in its last state to the offset control loop or the phase modulator scale factor loop based on determined higher dynamics of the environmental conditions.

9. The control system of claim 8 , wherein a modulation depth is changed in the phase modulator scale factor loop by the processor based on the environmental conditions.

10. The control system of claim 7 , wherein the analog gain factor is increased and the digital gain factor is decreased during low dynamic conditions to increase the sensitivity of the A/D converter, or the analog gain factor is decreased and the digital gain factor is increased during high dynamic conditions to mitigate saturation of the A/D converter.

11. The control system of claim 7 , further comprising a detection array that cooperates with the processor to monitor or control at least one of the AGC loop, the offset loop, and the phase modulator scale factor loop.

12. The control system of claim 11 , an offset correction module to correct electrical offsets of one or more circuits in the IMU, an offset detection module to detect the electrical offsets of the one or more circuits in the IMU, a scale factor detection module to detect scale factor offsets in the phase modulator scale factor loop, a rate loop module to control a modulation rate for the FOG, a modulation module that generates a modulation output sequence based on commands from the rate loop module, a phase modulator module that generates a digital command representing the modulation output sequence from the modulation module, a AO integration module to determine angular motion for the FOG, and a gain error detection module to determine gain error for the AGC loop.

13. A system, comprising:

a processor that operates one or more control loops that enable gyroscopic angular measurement for an inertial measurement unit (IMU), wherein each of the one or more control loops operates over a range of set points defined for each of the respective control loops;

a dynamic loop adjuster that receives environmental input data to determine environmental conditions for the IMU, wherein the dynamic loop adjuster alters at least one of the set points for at least one of the one or more control loops operated by the processor based on the determined environmental conditions;

a fiber optic gyroscope (FOG) circuit that generates a modulated optical signal representing angular motion for the IMU;

an optical receiver to convert the modulated output signal from the FOG to an electrical signal representing the angular motion of the IMU; and

an analog-to-digital (A/D) converter to convert the electrical signal from the optical receiver to a digital signal for the processor, wherein the processor employs an automatic gain control (AGC) loop to control the electrical signal gain of the optical receiver, employs an offset control loop to control electrical offsets in one or more circuits of the IMU, and a phase modulator scale factor loop to track sensitivity information of the modulated optical signal from the FOG.

14. The system of claim 13 , further comprising an interface that receives the environmental input data as external data from a remote data source from the IMU.

15. The system of claim 13 , further comprising a sensing circuit to sense the environmental conditions of the IMU.

16. The system of claim 13 , further comprising a dynamic auxiliary control loop operated by the processor that slows down output data changes or holds data in its last state to the offset control loop or the phase modulator scale factor loop based on determined higher dynamics of the environmental conditions.

17. The system of claim 13 , wherein the processor adjusts a gain of the AGC loop based on the environmental conditions in accordance with a digital gain factor and an analog gain factor, wherein the analog gain factor is increased and the digital gain factor is decreased during low dynamic conditions to increase the sensitivity of the A/D converter, or the analog gain factor is decreased and the digital gain factor is increased during high dynamic conditions to mitigate saturation of the A/D converter.

18. A method, comprising:

executing, by a processor, at least one of an automatic gain control (AGC) loop, an offset loop, and a phase modulator scale factor loop that enable gyroscopic angular measurement for an inertial measurement unit (IMU), wherein each of the at least one of the AGC loop, the offset loop, and the phase modulator scale loop operates over a range of set points defined for each of the respective control loop;

receiving, by the processor, environmental data relating to a dynamic condition of the IMU;

determining, by the processor, if the dynamic condition exceeds a predetermined threshold for the IMU based on the received environmental data; and

adjusting, by the processor, at least one of the AGC loop, the offset loop, and the phase modulator scale factor loop based on the determining, wherein a gain of the AGC loop is adjusted in accordance with a digital gain factor and an analog gain factor, wherein the analog gain factor is increased and the digital gain factor is decreased during low dynamic conditions, or the analog gain factor is decreased and the digital gain factor is increased during high dynamic conditions.

19. The method of claim 18 , further comprising receiving, by the processor, the environmental data from a remote data source or receiving the environmental data from a sensor associated with the IMU.