Magnetic Field Distortion Probe for Position Tracking Accuracy

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Solution Overview

Problem

Magnetic position tracking systems face measurement distortions due to metallic, paramagnetic, or ferromagnetic objects, which existing methods struggle to accurately compensate for, leading to potential inaccuracies in object positioning.

Innovation Solution

A probe with field generators and sensors attached to a common mechanical fixture is used to assess distortion levels by generating and sensing magnetic fields, with a processor calculating deviations from reference measurements and alerting users if thresholds are exceeded, employing various configurations such as linear and planar setups to account for different distances and orientations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If magnetic field measurements are used for position tracking, then position tracking capability is provided, but measurement distortion occurs due to metallic or ferromagnetic objects

Engineering Contradiction:
Improveposition tracking accuracyVSAvoidfield distortion
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

A probe serving as an intermediary device is introduced between the field-distorting objects and the position tracking system. This probe contains field generators and sensors that measure the actual magnetic field conditions in the workspace, enabling the system to detect and compensate for distortions caused by metallic or ferromagnetic objects present during medical procedures

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The system implements feedback by continuously measuring the magnetic field using the probe's sensors and comparing these measurements against expected field characteristics. The processor uses this feedback information to detect deviations caused by field-distorting objects and generates alerts or correction factors to maintain position tracking accuracy

Inventive Principle:
Principle #23Feedback

2Reliability

If existing distortion detection methods are used, then some field distortion detection is provided, but accurate position tracking measurements cannot be ensured during procedures

Engineering Contradiction:
Improveposition tracking reliabilityVSAvoidposition measurement accuracy
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The probe is pre-calibrated in free space before actual use to establish baseline field characteristics and sensor responses. This preliminary action stores reference data that enables the system to distinguish between normal field variations and distortions caused by metallic objects, ensuring reliable and accurate measurements during subsequent medical procedures

Inventive Principle:
Principle #10Preliminary action

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

This method effectively assesses and compensates for field distortions, ensuring accurate position tracking measurements by providing real-time alerts and correction factors, thereby improving the reliability of magnetic position tracking systems during medical procedures and installations.

Implementation Method 1

The field generators generate magnetic fields, which are sensed by the field sensors

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

The distortion is sometimes caused by eddy currents that are induced in such objects by the system's magnetic field

Methodology Applied
Scientific EffectEddy currents: Eddy Currents

Data Source

PatentEP1878384B1Probe for assessment of metal distortion
Publication Date: 2016.06.15 BIOSENSE WEBSTER INC
  • EP1878384B1 patent drawingFigure 1~2
  • EP1878384B1 patent drawingFigure 3A~3B
  • EP1878384B1 patent drawingFigure 4

AI summary

Apparatus for assessing field distortion includes a probe (56) and a processor. The probe includes a mechanical fixture (70) for placement at a location to be tested, and one or more field generators (62A,62B), which are attached to the mechanical fixture and are arranged to generate respective magnetic fields. The probe further includes one or more field sensors (66A,66B), which are attached to the mechanical fixture at known positions with respect to the one or more field sensors and are arranged to sense the magnetic fields generated by the one or more field generators and to output signals responsively to the sensed magnetic fields. The processor is arranged to process the signals so as to assess a distortion of the magnetic fields sensed by the field sensors at the tested location.