Deformable Surgical Instrument Shape Determination via Elasticity Model
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Solution Overview
Problem
Current surgical tracking technologies, such as electromagnetic tracking, are limited in the number of sensors they can simultaneously track, making it difficult to determine the shape of surgical instruments with deformable bodies, especially when only a few or even one tracking sensor is available.
Innovation Solution
A method that calculates the shape of a surgical instrument with a deformable body by defining influencing parameters, determining their values, and using an elasticity model to determine the spatial position and orientation of tracking sensors, allowing the overall shape to be calculated even with a limited number of sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electromagnetic tracking sensors are placed in the surgical instrument, then the position of the instrument can be tracked, but the number of sensors that can be placed is very limited due to restricted channels and space
Solution Approach 1:
The patent changes the approach from directly tracking multiple points to tracking a single point and calculating the positions of other points through parameter transformations. By using the known bending properties and control parameters (such as pull-wire displacement), the system calculates the positions of multiple instrument points from a single sensor measurement, effectively resolving the limitation of restricted sensor channels and space.
2Device complexity
If only one tracking sensor is placed in the instrument, then space and channel restrictions are minimized, but the shape of the instrument remains undisclosed
Solution Approach 1:
The patent introduces an intermediary calculation model based on bending properties that acts as a mediator between the single sensor measurement and the complete instrument shape. This model uses the relationship between control parameters (pull-wire displacement) and instrument deformation to reconstruct the full shape information from limited sensor data, effectively recovering the lost shape information without adding more sensors.
Solution Approach 2:
The patent replaces the mechanical approach of using multiple physical sensors with a computational approach using elasticity theory and bending models. Instead of mechanically placing multiple sensors throughout the instrument, the system uses mathematical models to calculate the positions of multiple points based on a single sensor reading and known instrument properties, substituting physical sensor arrays with computational reconstruction.
3Measurement precision
If multiple tracking sensors are placed throughout the instrument, then the shape can be directly measured, but the available space and tracking channels are exceeded
Solution Approach 1:
The patent extracts the essential information needed for shape determination from a single sensor position and control parameters, rather than requiring multiple sensors. By identifying that the single sensor position combined with known bending properties contains sufficient information to calculate the complete instrument shape, the system extracts only the necessary measurement data, eliminating the need for complex multi-sensor placements.
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
Enables accurate determination of the shape of surgical instruments with limited tracking sensors, enhancing precision in medical navigation and user understanding of instrument geometry during procedures.
Implementation Method 1
electromagnetic (EM) tracking technology provides the ability to track very tiny sensors
Implementation Method 2
providing bending or flexure properties of the surgical instrument; calculating the shape of at least one part of the surgical instrument with the aid of the bending or flexure properties
Data Source
Figure 1
AI summary
The present invention relates to a method for determining the spatial position and the shape of a surgical instrument (1) having a deformabie body (2), said method comprising the steps of: - providing an elasticity model of the surgical instrument (1); - defining at least one parameter which influences the shape of the instrument (1); - determining the spatial position and/or orientation of at least one tracking sensor (3) of the surgical instrument (1); - determining the value of the at least one parameter; - calculating the position and/or orientation of at least one part of the surgical instrument (1) with the aid of the elasticity model together with the determined value of the at least one parameter and the determined spatial position and/or orientation of the at least one tracking sensor (3). The present invention also relates to a surgical instrument (1) having a deformabie body (2) comprising at least two sensors (3, 4), wherein at least one sensor is a tracking sensor (3) and at least one other sensor is a sensor (4) which allows the value of a predetermined parameter influences the shape of the instrument (1) to be determined.