Multicore Optical Fiber Redundancy for Shape Sensing Error Detection
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Solution Overview
Problem
Existing shape sensing fiber applications face unforeseen or unpredictable errors due to operational, connection, calibration, and force-induced issues not accounted for in the model, necessitating a method to detect these errors independently.
Innovation Solution
A model with N degrees of freedom uses an additional redundant core to make N+1 measurements, allowing for error detection by comparing predicted and measured strains in the redundant core, thereby enhancing reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a multicore fiber with N cores is used for shape sensing, then N measurements can be obtained to determine N degrees of freedom (pitch, yaw, twist, elongation), but the system cannot detect unforeseen or unpredictable errors that are not included in the shape sensing model
Solution Approach 1:
The patent applies the copying principle by adding redundant core(s) that replicate the sensing functionality of the primary cores. These redundant cores serve as independent copies that can verify the accuracy of measurements from primary cores, enabling error detection without requiring fundamental changes to the sensing model. The redundant cores are processed through the same shape sensing model, and discrepancies between predicted and actual measurements indicate errors.
Solution Approach 2:
The patent implements preliminary action by pre-calculating expected strain values in redundant cores based on the shape sensing model and comparing them with actual measurements before finalizing shape determination. This preliminary verification step allows the system to detect errors in advance, ensuring reliability before committing to shape sensing results.
2Reliability
If additional redundant cores are added to detect errors, then error detection capability is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent applies universality by designing redundant cores that serve multiple functions: they act as primary sensing elements for shape measurement, serve as error detection mechanisms, and provide backup measurements. This multi-functionality reduces the need for separate error detection systems, simplifying overall system design and manufacturing while maintaining high reliability.
3Measurement precision
If the shape sensing model is expanded to account for more parameters, then measurement accuracy improves, but the model becomes more complex and may still miss unforeseen errors
Solution Approach 1:
The patent implements feedback by using measurements from redundant cores to verify and validate the shape sensing model predictions. The system continuously compares expected strain values (from the model) with actual measurements (from redundant cores), and when discrepancies are detected, it triggers error detection mechanisms. This feedback loop ensures measurement precision without requiring the model to account for every possible error source.
Data Source
AI summary
An optical fiber includes multiple optical cores configured in the fiber including a set of primary cores and an auxiliary core. An interferometric measurement system uses measurements from the multiple primary cores to predict a response from the auxiliary core. The predicted auxiliary core response is compared with the actual auxiliary core response to determine if they differ by more than a predetermined amount, in which case the measurements from the multiple primary cores may be deemed unreliable.