Magnetic Capsule Tracking With Grid Search for Esophageal Positioning

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Solution Overview

Problem

Existing magnetic field-based tracking methods for intragastric balloon capsules (MIBC) are computationally intensive and require numerous sensors, leading to high costs and limited tracking accuracy, particularly when the MIBC is inside the esophagus, posing a risk of damage.

Innovation Solution

A magnetic sensor-based tracking system using a magnetic field generating device and two magnetic field sensing devices, employing a grid search and dynamically confined search range with threshold modulation to track the MIBC's position along the esophagus, eliminating the need for inverse magnet model optimization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If optimization with forward magnet model is used for tracking, then tracking accuracy can be improved, but computational intensity increases and tracking frequency decreases

Engineering Contradiction:

Improvetracking accuracyVSAvoidtracking frequency

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The patent pre-calculates and stores magnetic field values at discrete grid points throughout the tracking volume before the actual tracking process. This preliminary computation creates a lookup table that allows real-time tracking to simply query pre-computed values rather than performing intensive optimization calculations, thereby maintaining accuracy while dramatically increasing tracking frequency.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent divides the continuous tracking volume into a discrete grid of points, and the magnetic field is pre-computed at each grid point. During tracking, the system segments the search space and uses the pre-computed grid values to quickly determine position, avoiding the need for continuous optimization calculations and enabling higher tracking frequency.

Inventive Principle:

Principle #1Segmentation

2Measurement precision

If inverse magnet model is solved for tracking, then tracking accuracy can be improved, but device complexity and number of sensors required increases

Engineering Contradiction:

Improvetracking accuracyVSAvoidnumber of sensors

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

Instead of using complex inverse magnet models that require solving difficult mathematical problems, the patent creates a simplified copy of the magnetic field data by pre-calculating field values at grid points. This copied data structure allows accurate tracking through simple comparison and interpolation operations, reducing the need for complex sensor arrangements and mathematical inversion.

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The patent replaces the complex mechanical/mathematical system of solving inverse magnet models with a simpler data lookup and interpolation system. By substituting the computational mechanics of optimization with pre-computed field maps, the system achieves comparable accuracy with fewer sensors and reduced device complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If many sensors are employed for tracking, then tracking accuracy is improved, but cost and computational effort increase

Engineering Contradiction:

Improvetracking accuracyVSAvoidcost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent uses a limited number of sensors (three magnetic field sensors) positioned strategically, rather than employing many sensors throughout the volume. The pre-computed grid data compensates for the fewer sensors by providing comprehensive spatial information, achieving good tracking accuracy with minimal sensor count and reduced cost.

Inventive Principle:

Principle #16Partial or excessive 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

The system achieves real-time tracking with an average one-dimensional position error of 3.48 mm, reducing computational complexity and cost while ensuring safe inflation of the MIBC by confirming its passage through the esophagus.

Implementation Method 1

Each of the one or more magnetic field sensing devices is configured in operation to be located within a sensible range of an expected path of the magnetic field generating device

Methodology Applied

Scientific EffectMagnetic field sensing: Magnetic Field

Data Source

PatentUS12465430B2Magnetic field based tracking methods and systems

Publication Date: 2025.11.11 NANYANG TECH UNIV

AI summary

A magnetic sensor-based tracking system, a method, and computer readable media for tracking an apparatus having a magnetic field generating device through an environment having a consistent magnetic field are provided. The magnetic sensor-based tracking system includes the apparatus having the magnetic field generating device, one or more magnetic field sensing devices, and a controller. Each of the one or more magnetic field sensing devices is configured in operation to be located within a sensible range of an expected path of the magnetic field generating device as it passes through the environment, the expected path including a plurality of regions. The controller is coupled to the one or more magnetic field sensing devices and configured in operation to utilize magnetic field sensing of the one or more magnetic field sensing devices to track the apparatus within the environment by obtaining at least one magnetic field reading from at least one of the one or more magnetic sensing devices and computing a position and an orientation of the apparatus within the environment based on at least one solution set obtained from a pre-obtained magnetic field model.