Fiber-optic gyroscope assembly with toroidal magnetic shield
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Solution Overview
Problem
Fiber-optic gyroscope (FOG) systems are susceptible to errors from external magnetic fields, temperature gradients, and vibrations due to their large size and cross-sectional dimensions, which affect the accuracy of rotation measurement.
Innovation Solution
A FOG assembly with a spool and magnetic shield forming a toroidal cavity, featuring a fiber coil with optical fibers counter-wound in first and second orientations, and a buffer material to reduce cross-sectional dimensions, thereby minimizing exposure to external influences and increasing optical fiber density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the FOG assembly uses a large fiber coil with traditional dimensions, then the optical path length is sufficient for measurement, but the assembly becomes susceptible to external magnetic fields, temperature gradients, and vibrations
Solution Approach 1:
The patent changes the geometric parameters of the fiber coil by reducing the axial dimension to be less than or equal to approximately 160% of the radial width, creating a compact coil structure that maintains optical path length while reducing susceptibility to external harmful factors
Solution Approach 2:
The fiber coil is nested within a toroidal cavity formed by the magnetic shield and flange, creating a protected interior space that shields the optical fiber from external magnetic fields and environmental variations
2Object-affected harmful factors
If the FOG assembly reduces the cross-sectional dimensions of the fiber coil, then susceptibility to external influences is minimized, but the optical fiber density increases making fabrication difficult
Solution Approach 1:
The patent specifies precise dimensional parameters for the fiber coil (axial dimension ≤ 160% of radial width) and optical fiber density (≥ 4341 fibers per square cm) to achieve the optimal balance between compact size and manufacturability
Solution Approach 2:
The patent describes a preliminary counter-winding process where optical fiber is wound in first and second orientations before applying potting material, which facilitates the formation of high-density coil structures that would be difficult to achieve with conventional single-pass methods
3Volume of moving object
If the FOG assembly uses a compact fiber coil design, then the size is reduced minimizing external influences, but the traditional counter-winding process becomes insufficient
Solution Approach 1:
The patent implements a preliminary counter-winding process where optical fiber is wound in first and second orientations before applying potting material, which facilitates the formation of high-density coil structures
Solution Approach 2:
The patent uses potting material as a composite binding agent to secure the counter-wound optical fiber in place, creating a stable fiber coil structure that maintains its compact dimensions and prevents deformation during operation
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 reduced size and fiber density of the FOG assembly mitigate errors from magnetic fields, temperature gradients, and vibrations, enhancing the accuracy and stability of rotation measurements.
Implementation Method 1
a magnetic shield arranged as a capped concentric cover about the sensitive axis and coupled to the spool and the flange to create a toroidal cavity between the magnetic shield and the flange
Implementation Method 2
a fiber optic gyroscope (FOG) can sense a change in orientation using the Sagnac effect, such as based on the interference of light which has passed through a coil of optical fiber
Data Source
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AI summary
One example includes a FOG assembly including a spool that includes a flattened portion corresponding to a flange comprising an axial center corresponding to a sensitive axis about which an associated FOG system is configured to measure rotation. The FOG assembly also includes a magnetic shield arranged as a capped concentric cover about the sensitive axis and coupled to the spool and the flange to create a toroidal cavity between the magnetic shield and the flange. A fiber coil is disposed within the toroidal cavity and coupled to the flange. The fiber coil includes an optical fiber which is counter-wound in first and second orientations. The fiber coil has an axial dimension along the sensitive axis that is less than or equal to approximately 160% of a radial width corresponding to a difference between an outer radius and an inner radius of the fiber coil.