Linear Structure Behavior Estimation Using Optical Fiber Feedback
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Solution Overview
Problem
Existing methods for estimating the behavior of linear structures in water, such as submarine cables, face challenges with error accumulation due to integral calculations and difficulty in acquiring continuous data at depth using optical fiber sensors and GPS-based position information.
Innovation Solution
A method using a distribution-type optical fiber sensor and Bayesian inference for parameter estimation, which involves expressing parameters in discrete values, forecasting behavior, calculating likelihood, updating discrete values based on observation data, and performing sequential data assimilation to enhance accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical fiber sensors are used to detect linear structure behavior, then long-distance dynamic measurement is enabled, but error accumulation occurs due to integral calculations along the optical fiber
Solution Approach 1:
The patent applies feedback by continuously comparing the measured linear structure behavior with predicted behavior from physical models, and using this comparison to correct and refine the measurements. This feedback loop prevents error accumulation by adjusting the measurement results based on their deviation from expected values, thereby maintaining both precision and reliability over long distances.
Solution Approach 2:
The patent replaces traditional mechanical measurement systems with optical fiber-based sensing systems that use light propagation principles. This substitution eliminates the mechanical error accumulation issues by using optical measurements that can be performed without physical contact along the entire structure, thereby improving both measurement precision and reliability.
2Productivity
If GPS-based position information is used for behavior estimation, then real-time estimation is enabled, but data acquisition becomes problematic at increased water depths
Solution Approach 1:
The patent introduces optical fiber sensors as an intermediary measurement system between the GPS surface-based positioning system and the underwater linear structure. This intermediary enables real-time behavior estimation by transmitting position and motion data from the structure through the optical fiber to the surface, where GPS data can be processed, thereby maintaining real-time estimation capability while overcoming the GPS signal attenuation problem at depth.
Solution Approach 2:
The patent substitutes GPS-based mechanical positioning with optical fiber-based sensing for underwater measurements. This substitution replaces the GPS signal transmission method with optical fiber data transmission, which can operate effectively at underwater depths where GPS signals cannot penetrate, thereby enabling real-time estimation while improving measurement precision at depth.
3Device complexity
If discrete parameter values are used for forecasting, then computational complexity is reduced, but estimation accuracy decreases
Solution Approach 1:
The patent applies dynamics by transitioning from static discrete parameter values to dynamic continuous parameter representations. The system uses probability density functions to represent parameter distributions that evolve over time, allowing for continuous refinement of estimates. This dynamic approach maintains computational efficiency while significantly improving estimation accuracy by capturing the temporal evolution of uncertainty in the linear structure behavior.
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
Enables highly accurate real-time behavior estimation of linear structures by reducing estimation errors and improving forecast accuracy through sequential data assimilation and likelihood-based updates.
Implementation Method 1
measuring a reflection spectrum of an optical fiber by using OFDR (Optical Frequency Domain Reflectometry) to derive a three-dimensional shape of a measured target
Data Source
AI summary
An object of the present disclosure is to enable behavior of a linear structure in water to be estimated. The present disclosure is an apparatus that: expresses at least one parameter in a plurality of discrete values, and forecasts behavior of a linear structure by using each of the discrete values; acquires behavior of the linear structure detected using an optical fiber; calculates a likelihood between the forecasted behavior of the linear structure and the acquired behavior of the linear structure; updates at least one of the plurality of discrete values on the basis of the likelihood; and calculates behavior of the linear structure by using the updated plurality of discrete values.