Flexible Medical Instrument Shape Sensing for Buckling Detection
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Solution Overview
Problem
Minimally invasive medical instruments are prone to buckling during insertion, which can compromise their effectiveness and control during surgical procedures.
Innovation Solution
A system that includes a teleoperated medical instrument with a shape constraint mechanism to prevent buckling, utilizing sensors to monitor the instrument's position, orientation, and shape, and a control system to adjust its trajectory to maintain a straight configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If minimally invasive medical instruments are inserted into the entry point, then the amount of tissue damage is reduced, but the section of the medical instrument outside the entry point becomes prone to buckling
Solution Approach 1:
The medical instrument is divided into multiple segments including a distal section, intermediate section, and proximal section. Shape sensors are distributed at multiple locations along the instrument's length to independently monitor each segment's configuration, enabling localized detection and control of buckling in specific segments while maintaining overall instrument functionality.
Solution Approach 2:
A control system acts as an intermediary between the shape sensors and the instrument's actuation mechanism. The control system processes shape data from sensors, determines buckling conditions, and generates control signals to adjust the instrument's configuration, thereby preventing buckling without requiring direct mechanical intervention.
2Stability of the object's composition
If the medical instrument is made more rigid to prevent buckling, then buckling resistance is improved, but the ability to navigate through natural orifices and tortuous paths is reduced
Solution Approach 1:
The medical instrument employs a dynamic structure with adjustable stiffness characteristics. The instrument can transition between a more flexible state for navigating tortuous anatomical paths and a more rigid state for maintaining positional stability during procedures. Shape sensors and control systems enable real-time adjustment of the instrument's mechanical properties to match procedural requirements.
Solution Approach 2:
The instrument's physical parameters such as stiffness, curvature, and diameter are made variable rather than fixed. By changing these parameters dynamically based on real-time shape sensor feedback and control system commands, the instrument can optimize its performance for both navigation through complex anatomy and resistance to buckling during insertion and manipulation.
3Measurement precision
If shape sensors are placed along the medical instrument to detect buckling, then buckling detection accuracy is improved, but the instrument complexity and manufacturing difficulty increase
Solution Approach 1:
The shape sensors serve multiple functions: detecting buckling, mapping the instrument's three-dimensional configuration, guiding navigation through anatomical structures, and providing feedback for control system adjustments. This multi-functionality justifies the added complexity by providing comprehensive data for various procedural requirements from a single sensor integration.
Solution Approach 2:
The shape sensors are integrated within the instrument's existing structural framework, with sensor elements nested within or along the instrument's segments. This nesting approach minimizes additional external components and allows the sensors to be incorporated into the instrument's manufacturing process rather than requiring separate assembly steps.
4Stability of the object's composition
If the section of the medical instrument outside the entry point is shortened to reduce buckling, then buckling resistance is improved, but the operator's control and access to the instrument are reduced
Solution Approach 1:
Shape sensors positioned along the instrument provide real-time feedback about the instrument's configuration both inside and outside the entry point. This feedback is processed by the control system to generate commands that maintain the instrument's desired shape and position. The feedback mechanism allows the operator to maintain control over a longer instrument exterior section without increased buckling risk, as the control system continuously adjusts based on sensor data.
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
A method comprises measuring, with a sensor, a shape of a section of an elongated flexible instrument and comparing the measured shape of the section of the elongated flexible instrument to an expected shape. The method also comprises determining whether the measured shape of the section of the elongated flexible instrument differs from the expected shape by a predefined threshold