Dual-Frequency IFOG Rate Computation for Drift Correction
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Solution Overview
Problem
Interferometric fiber optic gyros (IFOGs) face drift-related errors and performance degradation issues over time, requiring frequent recalibration, especially when events like fiber optic coil darkening occur.
Innovation Solution
A method and system that supply an optical input to an IFOG at two different frequencies, detect the responses, and compute the gyro rate as a function of the difference between these responses and a correction term, allowing for continuous operation without recalibration by accounting for time-dependent errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the IFOG operates continuously over time, then the gyro rate measurement is maintained, but drift-related errors grow and performance degrades requiring recalibration
Solution Approach 1:
The patent applies periodic frequency switching between two optical frequencies (first frequency and second frequency) to the IFOG system. By alternately modulating the light source at these two frequencies and comparing the phase differences, the system periodically corrects drift errors without requiring full recalibration, thus maintaining measurement accuracy over extended operational periods.
Solution Approach 2:
The patent changes the operating parameter by using two different optical frequencies instead of a single frequency. This parameter change enables the system to distinguish between Sagnac effect signals and drift errors, allowing continuous operation with maintained accuracy through differential measurement techniques.
2Measurement precision
If recalibration is performed frequently to maintain accuracy, then measurement precision is improved, but operational time and productivity are reduced
Solution Approach 1:
The patent implements a self-correcting mechanism where the IFOG system automatically compensates for its own drift errors by comparing measurements taken at two different frequencies. The system uses the difference in phase responses at these frequencies to calculate and correct drift-related errors, eliminating the need for external recalibration operations and maintaining continuous productivity.
3Duration of action of stationary object
If the fiber optic coil darkens due to degradation events, then the IFOG performance degrades, but the system continues operating without immediate failure
Solution Approach 1:
When fiber optic coil darkening occurs, the patent compensates by changing the measurement parameter from single-frequency to dual-frequency operation. The system measures phase differences at two frequencies and uses the differential signal to correct for intensity variations caused by darkening, maintaining measurement precision despite the degradation event.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables stable computation of the gyro rate without recalibration, even during performance degradation events, by using the difference in responses at two frequencies and pre-computed scale factors, thereby reducing the need for frequent recalibration and maintaining accurate navigation data.
Implementation Method 1
an interferometric fiber optic gyro (IFOG)... detecting a difference in responses of the IFOG to the optical input at the first and second frequencies... computing a gyro rate
Data Source
AI summary
A method comprises supplying an optical input to an interferometric fiber optic gyro (IFOG) at a first frequency and then a different second frequency; detecting a difference in responses of the IFOG to the optical input at the first and second frequencies; and computing a gyro rate as a function of the difference and a correction term.