Bidirectional Fiber-Optic Displacement Sensing With Blind-Spot Correction
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Solution Overview
Problem
Existing fiber-optic measurement systems face challenges in large-area and long-distance monitoring due to blind spots and error accumulation in strain measurements, making them economically inefficient and inaccurate for real-time deformation monitoring.
Innovation Solution
A distributed continuous high-accuracy bidirectional displacement fiber-optic measurement system using a Brillouin analysis device, optical fiber strain gauge, and fiber Bragg grating sensors to collect and process continuous and single-spot data, correcting for inconsistencies through distance average-weighted processes to generate accurate displacement data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If local key spots are monitored using FBG sensors, then measurement cost is reduced, but blind spots occur and complete field coverage is lost
Solution Approach 1:
The optical fiber is divided into multiple measurement intervals with discrete FBG sensors positioned at specific locations. Each FBG sensor measures strain at its specific position, and through numerical integration of strain data across intervals, complete displacement field information is reconstructed, eliminating blind spots while keeping sensor quantity minimal.
Solution Approach 2:
Numerical integration serves as an intermediary process that transforms discrete strain measurements from FBG sensors into continuous displacement field information. This mathematical intermediary allows reconstruction of complete field data from limited spot measurements, resolving the contradiction between cost and coverage.
2Loss of information
If a massive number of sensors are deployed to eliminate blind spots, then complete field coverage is achieved, but measurement cost increases significantly
Solution Approach 1:
Instead of deploying continuous dense sensors, the system segments the measurement task by placing FBG sensors only at critical intervals and using numerical integration to interpolate complete field information, dramatically reducing sensor quantity and cost while maintaining full coverage.
Solution Approach 2:
The system creates a virtual continuous measurement field through numerical integration algorithms that compute displacement values at unmeasured positions based on strain data from discrete FBG sensors, effectively copying measurement information to locations without physical sensors.
3Loss of information
If full-distribution strain measurement is conducted using BOTDA/BOTDR, then complete field coverage is achieved, but error accumulation occurs during numerical integration
Solution Approach 1:
The measurement domain is segmented into discrete intervals with FBG sensors at boundaries. Numerical integration is performed interval by interval with boundary condition checks at each segment, preventing error accumulation from propagating through the entire measurement chain and improving overall precision.
Solution Approach 2:
Boundary conditions are used as feedback checkpoints during numerical integration. At each interval boundary, the computed displacement is checked against physical constraints and previous measurements, allowing error detection and correction before errors accumulate further, thereby improving measurement precision.
4Measurement precision
If continuous numerical integration is performed without boundary condition checks, then complete displacement field is obtained, but error accumulation or divergence occurs
Solution Approach 1:
Boundary conditions serve as feedback mechanisms that continuously monitor and constrain the numerical integration process. At each boundary, physical constraints (such as fixed support conditions or continuity requirements) are enforced, preventing error accumulation and ensuring displacement accuracy is maintained throughout the entire measurement field.
Data Source
AI summary
The present invention discloses a distributed continuous high-accuracy bidirectional displacement fiber-optic measurement system and a measurement method thereof for measuring displacement of a measurement target, including a Brillouin analysis device connected with an optical fiber strain gauge, a fiber-optic sensor assembly including a reference fiber-optic sensor device and a plurality of fiber-optic sensor devices, and an operation module, the operation module is operable to receive the continuous data and the single-spot data transmitted from the Brillouin analysis device and the fiber-optic sensor devices, and to calculate an accurate displacement for each interval of the optical fiber strain gauge according to the continuous data and the single-spot data so as to form continuous displacement data. Thus, the present invention is economic in respect of cost and suits the need of the market application, and can be applied in a large area, and enhances the accuracy of measurement.