3D Volume Tracking Using Segmented Sensor Reference Frame
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Solution Overview
Problem
Existing 6 DOF electromagnetic tracking systems for surgical applications are cumbersome, expensive, and prone to inaccuracies due to sensor size and the need for full 6 DOF data, which can obstruct surgical procedures and increase computational complexity.
Innovation Solution
A system using a 6 DOF reference sensor and a marker sensor providing 3 DOF or 5 DOF tracking data within a 6 DOF coordinate system, allowing for accurate real-time tracking of a volume of interest with reduced sensor complexity and cost, suitable for surgical navigation and other applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a 6 DOF sensor is used to track the volume of interest, then the tracking accuracy is improved, but the sensor size increases causing obstruction in the working space and increased device complexity
Solution Approach 1:
The tracking system is segmented into two functional parts: a 6 DOF reference sensor that remains stationary and defines the coordinate system, and a simpler marker sensor (3 DOF or 5 DOF) that is attached to the volume of interest. This segmentation allows the reference sensor to provide the full 6 DOF coordinate framework while the marker sensor only needs to provide positional and partial orientation data, reducing the complexity and size of the sensor attached to the tissue.
Solution Approach 2:
The reference sensor acts as an intermediary that establishes a stable 6 DOF coordinate system. By having the reference sensor provide the complete coordinate framework and the marker sensor provide relative positioning within this framework, the system achieves accurate tracking without requiring the marker sensor to be a full 6 DOF device, thus reducing its size and complexity.
2Measurement precision
If a 6 DOF sensor is used to track the volume of interest, then the tracking accuracy is improved, but the cost and computational complexity increase
Solution Approach 1:
The system uses partial action by having the marker sensor provide only 3 DOF or 5 DOF data instead of full 6 DOF. The reference sensor provides the complete 6 DOF coordinate system, and the marker sensor provides partial data (position and sometimes orientation) relative to this framework. This partial data approach maintains tracking accuracy while reducing the computational burden of processing full 6 DOF data from both sensors.
3Measurement precision
If a wire or needle is inserted in the tissue volume of interest with a 6 DOF sensor, then the tracking capability is improved, but the wire spinning causes the sensor to report inaccurate orientation
Solution Approach 1:
The system segments the sensing functions so that the reference sensor (stationary) provides the stable 6 DOF coordinate system while the marker sensor (attached to needle/wire) provides only positional and limited orientation data. Since the marker sensor does not need to report full 6 DOF, the spinning of the wire/needle does not compromise the accuracy of the position tracking, and the limited orientation data from the marker sensor is supplemented by the stable reference frame.
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 system provides more accurate, smaller, and less expensive tracking, improving surgical precision and reducing the need for full 6 DOF data, as demonstrated by improved tumor localization in breast cancer surgery with reduced computational complexity and cost.
Implementation Method 1
A technique based on electromagnetic (EM) tracking that has shown good performance in a surgical application for tracking a tissue volume of interest
Data Source
AI summary
Provided are apparatus and methods for tracking a volume of interest in three dimensions in real time, using fewer than 6 DOF tracking information together with an external 6 DOE coordinate system. The apparatus and methods described herein provide more accurate, smaller, and less expensive tracking systems than prior approaches based on full 6 DOF tracking comprising translation and full orientation information. Embodiments may be used in applications such as surgical navigation, gaming, robotics, motion capture, and training.