Optical Fiber Shape Sensor Calibration for Telerobotic Surgery
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Solution Overview
Problem
Optical fiber shape sensors used in telerobotic surgical systems require calibration to accurately determine the shape and pose of kinematic chains, as existing methods fail to establish reliable reference frames and calibration relationships between the optical fiber and mechanical structures, affecting control precision.
Innovation Solution
A multicore optical fiber is associated with a kinematic chain, with strain sensed and used to define reference frames for both the fiber and the chain, allowing calibration relationships to be stored for accurate shape information correlation, enabling precise control through joint level, 3-D, and self-calibration methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical fiber shape sensing is used to determine the shape of a movable mechanical structure, then shape information can be obtained, but calibration is required to accurately relate the fiber's reference frame to the mechanical structure's reference frame
Solution Approach 1:
The patent performs calibration operations before the optical fiber shape sensor is deployed for actual shape measurement. A calibration apparatus is used to establish the reference frame relationship between the optical fiber and the mechanical structure in advance, storing calibration data that will be used during subsequent operation. This preliminary calibration action eliminates the need for complex real-time calibration during shape measurement, resolving the contradiction between measurement precision and device complexity.
2Reliability
If the optical fiber is calibrated to the mechanical structure, then accurate shape indication is achieved, but additional calibration apparatus and procedures are required
Solution Approach 1:
The patent introduces a calibration apparatus as an intermediary tool that facilitates the calibration process between the optical fiber and the mechanical structure. This calibration apparatus provides a standardized method and physical means to establish reference frame relationships, making the calibration process more systematic and reliable. The intermediary calibration apparatus resolves the contradiction by providing a structured approach that improves reliability while managing the complexity of system assembly through standardized procedures.
3Measurement precision
If joint level and 3-D calibration methods are implemented, then control precision is enhanced, but the calibration process becomes more complex
Solution Approach 1:
The patent divides the calibration process into distinct segments: joint level calibration for individual joint accuracy and 3-D calibration for overall spatial accuracy. Each calibration segment focuses on specific aspects of the system, allowing for systematic calibration of complex robotic structures. This segmentation enables high control precision through multiple specialized calibration stages while managing overall process complexity by breaking it into manageable, focused steps.
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 enables accurate calibration of optical fiber shape sensors to kinematic chains, enhancing control precision and reliability in telerobotic surgical systems by establishing reliable reference frames and calibration relationships, improving the system's ability to accurately indicate shape and pose.
Implementation Method 1
Strain is sensed in a segment of the optical fiber
Data Source
AI summary
Calibration methods and apparatuses for a shape sensing optical fiber are disclosed. Strain is sensed in an optical fiber that is associated with a kinematic chain, and information derived from the sensed strain is used to determine a calibration relationship between the fiber and the kinematic chain. The strain may be sensed at a plurality of angles between two links in the kinematic chain. The strain may be sensed in a segment of the optical fiber that is associated with a joint in the kinematic chain as the joint sweeps through an arc. The strain may be sensed for the optical fiber in a known, predefined bend shape. The calibration information is stored in memory for later use during operation of the kinematic chain, so that shape information from the optical fiber can be used to accurately indicate the shape or pose of the kinematic chain.