Multi-Core Fiber Bend Calculation for Reliable Safety Sensing
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Solution Overview
Problem
Existing bend sensing applications in optical fibers, such as those used in surgical robotic arms, face challenges in ensuring safe and reliable output without the use of redundant fibers due to space or cost constraints.
Innovation Solution
An interferometric measurement system with M primary cores and N redundant cores, where M > 2 and N > 1, uses data processing circuitry to compare primary and redundant core bend values, generating a signal when differences exceed a threshold, indicating unreliable measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a redundant fiber is used to ensure safe and reliable bend sensing output, then reliability is improved, but device complexity and space requirements increase
Solution Approach 1:
The patent combines multiple functions into a single optical fiber by integrating both primary measurement cores and redundant measurement cores within the same fiber structure. This merging approach allows the system to achieve redundant measurement capability without requiring separate redundant fibers, thereby improving reliability while avoiding the space and complexity penalties of using completely separate redundant fiber assemblies.
Solution Approach 2:
The single optical fiber is designed to perform multiple functions simultaneously: it serves as both the primary measurement fiber and the redundant measurement fiber. By incorporating multiple cores within one fiber that can independently perform bend sensing measurements, the system achieves multi-functionality, allowing one fiber to replace what would traditionally require multiple separate fibers.
2Reliability
If a redundant fiber is used to ensure safe and reliable bend sensing output, then reliability is improved, but space constraints are worsened
Solution Approach 1:
The patent implements a nested structure where multiple measurement cores are embedded within a single optical fiber cladding. The primary cores and redundant cores are nested within the same fiber body, allowing redundant measurement capability to be contained within the volume of a single fiber rather than requiring additional external space for separate redundant fibers.
Solution Approach 2:
By merging the primary and redundant measurement functions into a single fiber structure, the patent eliminates the need for separate redundant fiber assemblies that would occupy additional conduit space. This consolidation reduces the overall volume requirement while maintaining the reliability benefits of redundant measurement.
3Measurement precision
If multiple distributed strain measurements are combined through a system of equations, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent employs feedback mechanisms where the measurement system continuously monitors bend angles using multiple cores and compares the measurements against expected values or previously established relationships. The data processing system uses the strain measurements from multiple cores to calculate bend angles and curvature, with the ability to detect inconsistencies and generate fault signals when measurements diverge beyond acceptable thresholds, thereby improving precision through active verification.
Solution Approach 2:
The patent replaces complex mechanical measurement systems with optical-based interferometric measurements. By using optical phase measurements from multiple fiber cores and processing them through mathematical relationships, the system achieves high-precision bend angle measurement without the mechanical complexity of traditional encoders or mechanical sensors, substituting optical and computational methods for mechanical systems.
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
Ensures accurate and reliable bend sensing by detecting errors in optical and electronic circuitry, connections, calibration, or environmental forces, preventing potential hazards in robotic systems.
Implementation Method 1
An interferometric measurement system measures an optical fiber including M primary cores and N redundant cores
Data Source
AI summary
A fiber includes M primary cores and N redundant cores, where M an integer is greater than two and N is an integer greater than one. Interferometric circuitry detects interferometric pattern data associated with the M primary cores and the N redundant cores when the optical fiber is placed into a sensing position. Data processing circuitry calculates a primary core fiber bend value for the M primary cores and a redundant core fiber bend value for the N redundant cores based on a predetermined geometry of the M primary cores and the N redundant cores in the fiber and detected interferometric pattern data associated with the M primary cores and the N redundant cores. The primary core fiber bend value and the redundant core fiber bend value are compared in a comparison. The detected data for the M primary cores is determined reliable or unreliable based on the comparison. A signal is generated in response to an unreliable determination.