Ferromagnetic Detector with Motion-Adaptive False Alarm Control

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Solution Overview

Problem

Existing systems fail to accurately detect and alert ferrous objects that pose a projectile hazard in high magnetic fields, such as near MRI scanners, due to high false alarm rates and inability to adapt thresholds in real-time based on object motion and direction.

Innovation Solution

A system comprising a first sensor array of magnetic field sensors and a second sensor group for detecting object velocity and direction, with a processing unit that adjusts thresholds dynamically to generate alerts based on both magnetic field strength and object motion, reducing false alarms by integrating time-of-flight sensors and adaptive threshold adjustments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional magnetic field sensors are used to detect ferrous objects, then detection sensitivity is improved, but false alarm rate increases due to inability to distinguish hazardous objects from non-hazardous metal objects

Engineering Contradiction:
Improvedetection sensitivityVSAvoidfalse alarm rate
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The system dynamically adjusts detection thresholds based on real-time analysis of object motion characteristics. The processing unit modifies alert thresholds adaptively according to velocity and direction data from time-of-flight sensors, allowing the system to maintain high detection sensitivity while reducing false alarms by distinguishing between stationary/non-hazardous objects and moving/hazardous objects.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

Time-of-flight sensors serve as intermediary devices that provide motion information (velocity and direction) about detected objects. This intermediary data layer allows the processing unit to analyze object characteristics and determine hazard level without requiring direct contact or physical interaction with the detected objects, thereby reducing false alarms while maintaining detection accuracy.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Device complexity

If fixed detection thresholds are used, then system simplicity is maintained, but ability to adapt to different object velocities and directions is reduced

Engineering Contradiction:
Improvesystem simplicityVSAvoidthreshold adaptability
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The system transitions from static fixed thresholds to dynamic adaptive thresholds that automatically adjust based on real-time object motion characteristics. The processing unit continuously modifies detection thresholds according to velocity and direction data, enabling the system to adapt to various scenarios (slow-moving vs. fast-moving objects, different directions of approach) while maintaining operational simplicity through automated adjustment.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system implements feedback loops where detection results and motion analysis feed back into threshold adjustment mechanisms. The processing unit uses information from time-of-flight sensors about object velocity and direction to continuously refine and adjust detection thresholds, creating a self-adapting system that improves its performance based on observed conditions without requiring manual reconfiguration.

Inventive Principle:
Principle #23Feedback

3Measurement precision

If multiple sensor types are integrated, then detection accuracy and threat analysis capability are improved, but system complexity increases

Engineering Contradiction:
Improvedetection accuracyVSAvoidsystem complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The system merges magnetic field sensors and time-of-flight sensors into an integrated detection system. By combining these different sensor types, the system achieves enhanced detection accuracy and comprehensive threat analysis capability, as each sensor type compensates for the limitations of the other and provides complementary information about detected objects.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The processing unit is designed with multi-functionality to handle data from both magnetic field sensors and time-of-flight sensors. It performs multiple functions including initial object detection, motion parameter extraction (velocity and direction), threshold adjustment, and hazard level determination, thereby managing the complexity of multiple sensor types through a unified, versatile processing architecture.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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

Enhances safety by accurately identifying potential projectile hazards near MRI scanners, reducing false alarms, and ensuring timely alerts through real-time adaptive threshold adjustments based on object velocity and direction.

Implementation Method 1

a first sensor array including one or more magnetic field sensors configured to generate a first signal in response to detecting a magnetic field

Methodology Applied
Scientific EffectMagnetic field detection: Magnetic Field

Implementation Method 2

The second signal includes information relating to a velocity of an object and direction of motion of the object

Methodology Applied
Scientific EffectTime of flight: Time of Flight

Data Source

PatentEP4402517B1Ferromagnetic detector and threat analysis
Publication Date: 2025.09.03 IRADIMED CORP
  • EP4402517B1 patent drawingFigure 1
  • EP4402517B1 patent drawingFigure 2
  • EP4402517B1 patent drawingFigure 3~4

AI summary

Apparatus, systems and processes for detection of objects representing possible projectile hazards in areas of high magnetic fields such as those potentially hazardous ferrous objects which may be moved within the region of forceful magnetic attraction by magnetic resonance imaging (MRI) scanners. The systems and process may include multiple magnetic field sensors and multiple time of flight sensors positioned around a passageway. The time of flight sensors may facilitate determination of movement (e.g., speed and/or direction) of the potentially hazardous ferrous object to provide enhanced accuracy of threat detection.