Underwater Polarization Imaging for Turbid-Water Navigation
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Solution Overview
Problem
Current navigation technologies such as GPS, WiFi, acoustic, and magnetic compasses are limited in underwater applications, especially for long-distance navigation, and polarization navigation is underdeveloped, requiring manual operation and suffering from measurement errors due to water turbidity and scattering.
Innovation Solution
A dual-camera full-Stokes underwater polarization imaging system with a small angle of view lens and automated control, using a comprehensive model for skylight polarization mapping to minimize location measurement errors, capable of operating in clear and turbid waters up to 100 meters deep without requiring references.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If GPS is used for underwater navigation, then positioning is available, but it is limited to very shallow water (within a few meters) due to strong signal attenuation
Solution Approach 1:
The patent replaces electromagnetic wave-based GPS with optical polarization-based navigation. By using polarization patterns of sunlight that penetrate water, the system enables navigation at depths where GPS signals cannot reach, achieving both deep-water operation and reliable positioning through optical rather than electromagnetic means.
Solution Approach 2:
The patent introduces polarization patterns as an intermediary carrier for navigation information. These polarization patterns serve as a mediator between the sun (information source) and the underwater sensor, allowing navigation data to be transmitted through water where direct electromagnetic signals fail.
2Adaptability or versatility
If acoustic navigation systems are used, then deep ocean navigation is possible, but they require predetermined reference locations and are not suitable for long-distance navigation
Solution Approach 1:
The polarization navigation system is self-service in that it uses the sun's polarization patterns as a natural, always-available reference framework. The system automatically determines position and orientation relative to the sun without requiring external reference locations or complex infrastructure, enabling autonomous long-distance navigation at any depth.
Solution Approach 2:
The patent creates a universal navigation system that works at any depth and anywhere on the globe by relying on the sun's polarization patterns. This single system replaces the need for multiple depth-specific systems (acoustic for deep water, GPS for shallow water) and eliminates the need for predetermined reference locations.
3Adaptability or versatility
If underwater magnetic or gyro compass is used, then deep ocean navigation is possible, but they require references for error correction and geolocation
Solution Approach 1:
The patent replaces mechanical compass systems (magnetic or gyroscopic) with optical polarization-based measurement. By detecting the polarization angle of sunlight, the system directly obtains orientation information relative to the sun, eliminating the need for magnetic references and providing direct geolocation capability at any depth.
Solution Approach 2:
The patent uses polarization patterns as an intermediary that directly links the observer's orientation to geographic coordinates. Through the polarization angle measurement and the known relationship between sun position and polarization patterns, the system obtains direct geolocation without requiring intermediate magnetic or gyroscopic references.
4Adaptability or versatility
If polarization navigation is used, then long-range geolocation without references is possible, but water turbidity causes large measurement errors
Solution Approach 1:
The patent implements feedback through iterative optimization to correct measurement errors caused by turbidity. The system uses the measured polarization patterns, compares them with theoretical models, and iteratively adjusts the position estimate to minimize discrepancies, thereby recovering accurate location information even in turbid water where direct measurement is degraded.
Solution Approach 2:
The patent addresses turbidity by changing the approach from direct polarization measurement to a model-based inference system. By parameterizing the effects of scattering and turbidity and using optimization algorithms, the system adapts to varying water conditions and maintains positioning accuracy across different turbidity levels.
5Ease of operation
If conventional polarization imaging system is used, then navigation is possible, but manual operation is required and system is not automated
Solution Approach 1:
The patent makes the system self-service by automatically performing the navigation tasks without manual intervention. The automated image processing pipeline independently completes polarization pattern extraction, position calculation, and navigation guidance, allowing the system to operate autonomously and simplifying user interaction.
Solution Approach 2:
The patent performs preliminary automated processing of polarization images to pre-calculate navigation parameters and generate guidance information before the actual navigation task. This preliminary action enables the system to be ready for immediate use and reduces the operational burden on the user during navigation.
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
Achieves high accuracy in sun position determination (0.35° azimuth and 0.03° zenith) and location prediction error of ~23 Km in clear water, and ~100 Km in turbid water, with automated operation and reduced polarization aberration.
Implementation Method 1
Mapping the underwater light polarization is a viable solution to this problem as the map of the polarization state of light, coming from different directions, is dependent on the specific coordinate system connecting the position of the observer and the position of the source, the sun.
Implementation Method 2
A comprehensive model for the skylight polarization mapping is provided considering the scattering of light inside the turbid water body.
Data Source
AI summary
A polarization-based underwater navigation and global positioning system is disclosed that includes dual polarization cameras comprising a small angle view imaging lens configured to detect full Stokes parameters simultaneously and a computer system programmed with a model for a skylight polarization mapping with a scattering model of light inside turbid water.