Portable Optical Gyroscope Compass With Fiber-Photonic Integration
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Solution Overview
Problem
Existing portable gyroscopes, particularly mechanical MEMS-based gyroscopes, suffer from high bias instability and thermal errors, making them impractical for navigation in environments without global positioning signals, and high-performance fiber optical gyroscopes are too large for portable devices.
Innovation Solution
Integrate a fiber optical gyroscope for one critical axis and integrated photonics-based optical gyroscopes for the other axes, using a modular design with a rigid frame to support the fiber coil, and utilize the Earth's rotation for navigation, independent of magnetic fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If mechanical MEMS-based gyroscopes are used, then the device size is reduced and cost is lowered, but measurement precision and reliability deteriorate due to high bias instability and thermal errors
Solution Approach 1:
The patent replaces mechanical MEMS gyroscopes with optical gyroscopes that use light interference patterns to detect rotation. The optical gyroscope uses a light source, beam splitter, mirrors, and detector to measure angular velocity through the Sagnac effect, eliminating mechanical moving parts while achieving superior bias stability below 0.1°/Hr and immunity to thermal errors
Solution Approach 2:
The patent changes the fundamental measurement parameter from mechanical displacement to optical phase difference. By measuring the phase difference of light waves traveling in opposite directions around a closed path, the system achieves high precision angular velocity measurement without the thermal drift and bias instability inherent in mechanical systems
2Measurement precision
If high-performance fiber optical gyroscopes are used, then measurement precision is improved, but device size increases making them unsuitable for portable applications
Solution Approach 1:
The patent transitions from fiber-optic implementation to integrated photonic circuit implementation, moving the optical path from three-dimensional fiber coils to two-dimensional planar waveguide structures. This dimensional change enables compact integration while maintaining the optical interference measurement principle, achieving portable form factor with high precision
Solution Approach 2:
The patent merges multiple optical components (light source, beam splitter, mirrors, detectors) into a single integrated photonic chip. The integrated circuit combines all optical elements on one substrate, eliminating the need for separate fiber optic components and enabling portable device integration while achieving bias stability below 0.1°/Hr
3Ease of manufacture
If mechanical gyroscopes with moving parts are used, then ease of manufacture is improved, but reliability deteriorates due to susceptibility to shock, vibration and temperature variation
Solution Approach 1:
The patent replaces mechanical gyroscopes with optical gyroscopes that have no moving parts. The optical system uses stationary components (light source, beam splitter, mirrors, detectors) to measure rotation through light interference, providing immunity to shock, vibration, and temperature variations while maintaining manufacturability through integrated photonic circuits
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
Provides ultra-high precision navigation with bias stability below 0.1°/Hr, immune to magnetic disturbances, and enables accurate positional prediction in centimeter ranges, suitable for handheld and wearable devices.
Implementation Method 1
Optical gyroscopes typically have the highest performance and rely on interferometric measurements based on the Sagnac effect (a phenomenon encountered in interferometry that is elicited by rotation)
Implementation Method 2
Optical gyroscopes typically have the highest performance and rely on interferometric measurements based on the Sagnac effect
Data Source
AI summary
The present disclosure relates to integration of integrated photonics-based optical gyroscopes and fiber-based optical gyroscopes into portable apparatuses that may include compass features. Novel small-footprint modularized fully integrated photonics optical gyroscopes are used for non-critical axes. However, for at least one critical axis, a fiber-optic gyroscope can be used to provide bias stability below 0.1°/Hr, which is directly correlated to predicting positional accuracy in the centimeter range. The positional accuracy results from the compassing ability of the gyroscope (referred to as gyrocompass) to calculate direction of heading using the earth's rotation.