Fiber Optic Gyroscope Vibration Error Suppression
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Solution Overview
Problem
Fiber optic gyroscopes face sensitivity issues due to low rotation rates and vibration-induced bias errors, particularly in severe vibration environments like missile guidance systems, where existing technologies struggle to suppress vibration-induced intensity and phase fluctuations effectively.
Innovation Solution
A system comprising a light source, sensing loop assembly, photo detector, and processing component that modulates light intensity and phase signals to determine and rescale the intensity modulation amplitude, thereby eliminating vibration-induced rotation rate errors, using a processing component to generate analog and digital signals for controlling the sensing loop assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the fiber sensing coil length and diameter are increased to improve sensitivity, then the scale factor increases and the FOG becomes more sensitive to rotation, but the device complexity and size increase
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the phase modulation depth based on detected vibration intensity. When vibration is detected, the system modifies the modulation parameter to compensate for vibration-induced errors, thereby maintaining high measurement precision without requiring increased coil size or complexity
2Measurement precision
If phase modulation is applied to improve sensitivity for low rotation rates, then the output signal sensitivity improves, but vibration-induced intensity and phase fluctuations increase causing rectified bias error
Solution Approach 1:
The patent implements feedback by continuously monitoring the intensity modulation amplitude and using this information to adjust the phase modulation depth. The system detects vibration through intensity fluctuations and feeds this information back to modify the modulation strategy, thereby reducing rectified bias error while maintaining sensitivity to low rotation rates
Solution Approach 2:
The system dynamically adjusts the phase modulation depth based on real-time vibration conditions. Rather than using fixed modulation parameters, the system adapts the modulation depth according to the detected vibration intensity, optimizing performance across varying operational conditions and minimizing vibration-induced errors
3Adaptability or versatility
If the FOG operates in severe vibration environments, then it can function in demanding applications such as missile guidance, but rectified bias error increases due to synchronous intensity and phase modulations
Solution Approach 1:
The patent converts the harmful effect of vibration-induced intensity modulation into a useful signal. By detecting and measuring the intensity modulation amplitude, the system uses this previously harmful information to diagnose vibration conditions and adjust the phase modulation depth accordingly, thereby transforming the harmful vibration effect into a basis for compensation and improved accuracy
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
The solution significantly reduces vibration-induced bias errors, enhancing the sensitivity and accuracy of fiber optic gyroscopes by accurately rescaling phase signals and correcting for gyro rotation rates, even in harsh vibration conditions.
Implementation Method 1
If the coil is rotated about the axis, the effective optical path length for the light traveling in one direction in the coil is increased, while the path length is decreased for the light traveling in the opposite direction. The difference in path length introduces a phase shift, known as the Sagnac Effect, between the light waves traveling in opposite directions.
Implementation Method 2
Light is injected in opposite directions through the coil and directed onto a photo detector. An interference pattern is detected by the photo detector, which indicates that the FOG is experiencing rotation.
Implementation Method 3
Vibration also causes phase fluctuation through physical rotation of the IFOG sensing coil.
Data Source
AI summary
Systems and methods for performing vibration error suppression in a fiber optic gyro sensor. An example system includes a light source, a sensing loop assembly, a photo detector, and a processing component. The light source generates a light signal that is then modulated by the sensing loop assembly and applied to a fiber optic coil in the assembly. The photo detector receives a modulated light signal that is an output of the sensing loop assembly (coil) and generates an analog signal. The processing component converts the generated analog signal into a modulated digital signal, determines an average of the modulated digital signal, determines an intensity modulation amplitude based on the determined average of the modulated digital signal, and re-scales the modulated digital phase signal based on the determined intensity modulation amplitude.