Resonant Fiber Optic Gyroscope Bias Error Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Resonant fiber optic gyroscopes (RFOGs) are susceptible to bias errors due to imperfections in optical components, such as birefringence, which create parasitic light waves that cannot be distinguished from desired light signals, leading to varying errors over time, including temperature changes.
Innovation Solution
A method is implemented to generate a waveform and measure signals representative of angular rotation rate in the linear region of the waveform, with processing to diminish bias error at the maxima and minima, using a PZT voltage source to modulate the optical path length of the fiber coil and adjust the frequencies of light signals to suppress bias errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If RFOGs use smaller diameter to reduce size of inertial navigation systems, then the device volume is reduced, but rotation sensitivity decreases
Solution Approach 1:
The patent changes the operating parameters of the RFOG by modulating the optical path length using a PZT voltage source, creating a waveform that operates in a linear region where bias error is minimized. This allows the system to maintain high rotation sensitivity while using smaller diameter fiber coils, thus reducing the overall device volume.
2Measurement precision
If RFOGs use optical components with higher precision to reduce bias error, then measurement precision is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
Instead of trying to eliminate birefringence and parasitic light waves through perfect optical components, the patent converts the harmful bias error into a manageable signal by operating in a specific linear region of a waveform. The PZT modulation creates conditions where bias error can be averaged to zero, transforming an unavoidable component imperfection into a controllable parameter.
Solution Approach 2:
The patent applies periodic modulation to the optical path length using a PZT voltage source, creating a waveform that periodically passes through a linear region. By synchronizing measurements with this periodic action and averaging over multiple cycles, the system eliminates bias error without requiring higher precision optical components.
3Productivity
If RFOGs operate continuously to maintain stable measurements, then productivity is improved, but bias error varies over time due to temperature changes
Solution Approach 1:
The patent implements periodic modulation of the optical path length that creates a repeating waveform with a linear region. By continuously operating in this manner and averaging measurements over each period, the system maintains continuous productivity while the periodic structure ensures that temperature drift and other time-varying effects average out, maintaining measurement precision.
Solution Approach 2:
The system uses feedback by monitoring the waveform and identifying the linear region, then adjusting measurements to occur during this specific phase. This feedback mechanism ensures that even as temperature and other environmental factors change over time, the measurements consistently occur under optimal conditions where bias error is minimized.
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
This approach effectively reduces bias errors in RFOGs by averaging them to zero in linear regions and minimizing variations at maxima and minima, resulting in more accurate angular rotation rate measurements.
Implementation Method 1
a PZT voltage source to modulate the optical path length of the fiber coil and adjust the frequencies of light signals
Implementation Method 2
Resonant fiber optic gyroscopes (RFOGs) have better rotation sensitivity for a given diameter then laser ring gyroscopes and interferometer fiber optic gyroscopes
Implementation Method 3
imperfections in optical components, e.g. due to birefringence, which create of one or more parasitic light waves having undesired polarization states
Data Source
AI summary
In one embodiment, a method is provided. The method comprises generating a waveform; measuring signals representative of angular rotation rate in a linear region of the waveform; and diminishing bias error about at least one of a waveform's maxima and minima.