Magnetic Sensor Group Noise Cancellation for Wearable Biomagnetism
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional gradiometers have limitations in measuring weak magnetic fields from living bodies due to insufficient noise reduction, large and heavy structures, and difficulty in being portable and wearable, especially when exposed to various magnetic noise components.
Innovation Solution
A magnetic field measurement apparatus comprising a magnetic sensor group with multiple sensors, an average value calculating unit, and a noise removing unit that calculates and subtracts common noise components from observed quantities to isolate the magnetic field from the object, allowing for reduced size and portability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional gradiometer uses a reference sensor disposed at a distance of 5 cm to 10 cm from the measurement sensor, then external magnetic field noise can be detected, but the noise reduction rate is insufficient in environments with various magnetic field noise components
Solution Approach 1:
The invention divides the noise removal task into multiple independent processing channels, each handling a specific frequency band or noise component. Instead of using a single reference sensor, the system segments the magnetic field detection into multiple measurement sensors and processes each channel's noise independently, allowing more precise noise cancellation in complex electromagnetic environments.
Solution Approach 2:
The invention introduces an intermediary processing unit that calculates the average value of observed quantities from multiple magnetic sensors to estimate the common noise component. This intermediary calculation step serves as a mediator between raw sensor data and final noise-cancelled output, enabling more accurate noise removal by considering the statistical properties of multiple measurements.
2Measurement precision
If a magnetic shield chamber made of permalloy is used to prevent external magnetic field intrusion, then measurement accuracy is improved, but the apparatus becomes large and heavy
Solution Approach 1:
The invention extracts and removes the heavy magnetic shield chamber from the system by using software-based noise cancellation algorithms instead of physical shielding. The common noise component is extracted from the observed quantities of multiple sensors and subtracted from the measurement, achieving magnetic field isolation through computation rather than through heavy permalloy materials.
Solution Approach 2:
The invention replaces the mechanical magnetic shield chamber with an electronic and computational noise removal system. Instead of using physical permalloy barriers to block magnetic fields, the system uses multiple magnetic sensors combined with signal processing algorithms to electronically cancel noise, substituting mechanical shielding with electronic field cancellation.
3Measurement precision
If a magnetic shield chamber is used for measurement, then external magnetic field interference is eliminated, but the apparatus becomes difficult to carry and operate outdoors
Solution Approach 1:
The invention extracts the noise cancellation function from the heavy magnetic shield chamber, separating the essential noise removal capability from the cumbersome physical structure. By calculating the average value of observed quantities from multiple sensors and using this as an estimate of the common noise component, the system achieves portability while maintaining noise immunity.
4Measurement precision
If the reference sensor is disposed at a distance from the measurement sensor, then external magnetic field detection is enabled, but the apparatus cannot be made into a thin type wearable sensor for close contact with the object
Solution Approach 1:
The invention segments the noise detection function across multiple measurement sensors rather than relying on a single reference sensor at a distance. By distributing sensors and processing their individual observed quantities separately, the system achieves noise detection capability in a thin, wearable configuration where sensors must be close to the measurement object.
Solution Approach 2:
The invention transitions from a spatial separation approach (reference sensor at distance) to a computational dimension approach (average value calculation of multiple close sensors). Instead of separating sensors physically in space, the system separates noise detection from measurement by processing data in the computational domain, enabling thin wearable design.
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 effective measurement of weak magnetic signals without a magnetic shield chamber, achieving noise reduction and enabling the apparatus to be made smaller and more portable for use on living bodies.
Implementation Method 1
a magnetic sensor group including a plurality of magnetic sensors
Data Source
AI summary
In a magnetic field measurement apparatus and a magnetic field measurement method provided herein, a magnetic field from an object is measured by a magnetic sensor group including a plurality of magnetic sensors. Then, an estimated value of a common noise component included in observed quantities of the magnetic sensors of all the channels of the magnetic sensor group is obtained as an external magnetic noise component. Finally the magnetic signal from the object is calculated by subtracting the estimated value from the observed quantity of each of the magnetic sensors.