Optical Fiber Shape Sensing for Medical Instrument Coil Control
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Solution Overview
Problem
Complications arise during minimally invasive procedures due to elongated medical instruments winding up or coiling at their tips, storing kinetic energy that can damage the body, particularly in robotic procedures lacking haptic feedback.
Innovation Solution
A method and apparatus using an optical fiber along the instrument for shape capture, measuring bends and bending forces to determine a sequence of movements that minimize these forces, allowing the instrument to be guided safely through the body.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the instrument is inserted deep into the body to reach distant targets, then the treatment capability is improved, but the instrument winds up and coils at its tip storing kinetic energy that may damage the body
Solution Approach 1:
The system performs preliminary measurement of the instrument's three-dimensional shape and bending forces before the instrument is fully inserted or manipulated. Based on these preliminary measurements, the control system calculates and outputs a sequence of movements that prevents excessive bending and coiling from occurring in the first place, thereby eliminating the harmful kinetic energy storage before it can cause damage
Solution Approach 2:
The system continuously measures the actual three-dimensional shape and bending forces of the instrument during insertion and manipulation. This real-time feedback is used to adjust and optimize the sequence of movements, ensuring that the instrument maintains a safe configuration and does not accumulate dangerous levels of kinetic energy through excessive coiling or winding
2Measurement precision
If robotic procedures are used to improve precision, then the manipulation accuracy is improved, but the lack of haptic feedback makes it difficult to detect instrument coiling and bending
Solution Approach 1:
The system replaces the missing haptic feedback mechanism with an optical measurement system. Instead of relying on the operator's tactile sense to detect instrument coiling and bending, the system uses optical fibers or other sensing mechanisms to measure the actual three-dimensional shape and bending forces, converting mechanical information into optical or electrical signals that can be processed and displayed
Solution Approach 2:
The system introduces an intermediary measurement system that acts as a sensor between the instrument and the control system. This intermediary device (optical fiber, shape sensor) directly measures the instrument's configuration and transmits this information to the control system, compensating for the lack of direct haptic feedback and enabling precise detection of coiling and bending
3Adaptability or versatility
If the instrument flexibility is increased to navigate complex body pathways, then the adaptability is improved, but the instrument stores more elastic energy that can cause damage upon sudden unwinding
Solution Approach 1:
Before the instrument is manipulated to navigate complex pathways, the system measures the current three-dimensional shape and calculates the bending forces. Based on this preliminary assessment, the control system generates a movement sequence that guides the instrument through the complex pathway while maintaining bending forces below dangerous thresholds, preventing excessive elastic energy accumulation
Solution Approach 2:
The system dynamically adjusts the sequence of movements based on real-time measurements of the instrument's shape and bending forces. As the instrument navigates complex pathways and encounters resistance or begins to coil, the control system modifies the movement sequence to reduce bending forces and prevent excessive elastic energy storage, adapting the control strategy to the current state of the instrument
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
Prevents instrument coiling by optimizing its shape and reducing bending forces, ensuring safe and controlled movement within the body.
Implementation Method 1
an optical fiber configured for optical shape capture
Data Source
AI summary
A method for controlling movement of an elongated medical instrument within a body that along its length includes an optical fiber configured for optical shape capture is provided. An insertion section of the fiber is located in the body. The method includes measuring a bend at multiple positions of the fiber, at least along the insertion section of the fiber. A three-dimensional (3D) shape of the insertion section of the fiber in the body is determined from the measured bend. A sequence of movements, with which a holding section of the instrument is to be moved, is determined based on the shape of the insertion section, so that the bend of the instrument in the insertion section may be decreased if the holding section is moved correspondingly. The sequence of movements is output.