Redundant-Core Multicore Optical Fiber for Shape-Sensing Safety
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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 solution to detect these errors independently.
Innovation Solution
A model with N degrees of freedom is enhanced by incorporating an auxiliary or redundant core to make N+1 measurements, allowing for an additional check on the model's accuracy, and an interferometric system is used to detect and compensate for errors by comparing predicted and measured strains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
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:
An auxiliary core is added to the multicore fiber to provide an additional measurement channel. This core is configured to measure strain along the fiber axis, providing redundant information that can be used to detect errors independent of the shape sensing model. The auxiliary core enables the system to perform error detection in advance before errors affect the accuracy of shape sensing measurements.
Solution Approach 2:
The auxiliary core acts as an intermediary element that provides independent verification of the shape sensing model's accuracy. By comparing the strain measurement from the auxiliary core with the strain predicted by the shape sensing model, the system can identify discrepancies indicating model errors, operational errors, or environmental factors not accounted for in the original N-core configuration.
2Reliability
If an auxiliary core is added to provide N+1 measurements for error detection, then the reliability and error detection capability are improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The auxiliary core is designed to serve multiple functions: it provides strain measurement along the fiber axis for error detection, and can also contribute to temperature sensing when combined with other cores. This multi-functionality reduces the need for separate dedicated error detection systems and maximizes the utility of the additional core.
Solution Approach 2:
The patent explores different configurations of the auxiliary core, including positioning it at the center of the fiber or at the periphery, and varying its orientation relative to the other cores. These parameter changes allow optimization of the fiber structure for specific applications while maintaining the error detection capability.
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
The solution effectively detects errors of unknown origin without prior knowledge, enhancing the reliability and confidence of shape sensing measurements by identifying discrepancies between predicted and actual strains.
Implementation Method 1
Interferometric detection circuitry is configured to detect measurement interferometric pattern data associated with each of the multiple primary cores and the auxiliary core
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.