Hardness Measurement Using Magnetic Sensor and Acceleration Data

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Solution Overview

Problem

Existing methods for measuring human body hardness, such as durometers and acceleration sensors, face accuracy issues due to sinkage and integration errors, making them unsuitable for precise measurements on soft tissues like the human body.

Innovation Solution

A hardness measurement system using a magnetic sensor, acceleration sensor, and displacement sensor to calculate the spring constant of the body by processing electric voltage and acceleration information, eliminating the need for displacement sensors and reducing integration errors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If acceleration is integrated two times to measure hardness, then measurement can be performed, but measurement accuracy deteriorates due to large integration errors

Engineering Contradiction:

Improvehardness measurement capabilityVSAvoidhardness measurement accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent replaces the mechanical integration process with a magnetic field-based measurement system. Instead of integrating acceleration data mechanically (which accumulates errors), the system uses a magnetic sensor to directly detect the position of the needle relative to the body surface, substituting the error-prone mechanical integration process with a direct magnetic field measurement approach.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a magnetic field as an intermediary between the needle and the measurement system. The magnetic sensor detects changes in the magnetic field caused by needle penetration, providing an intermediate measurement that avoids direct integration of acceleration data and thereby reduces cumulative errors.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If durometer is used to measure hardness, then measurement can be performed on rigid materials, but measurement accuracy deteriorates for soft tissues like human body due to sinkage

Engineering Contradiction:

Improvesuitability for different materialsVSAvoidhardness measurement accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent makes the measurement system dynamic by allowing the needle to freely penetrate the body surface and by using a magnetic sensor that can detect position changes during penetration. This dynamic approach adapts to the varying depth and resistance encountered when measuring soft tissues, unlike static durometer methods that assume fixed reference points.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the measurement parameter from fixed surface indentation (durometer) to dynamic needle penetration depth detected by magnetic field changes. This parameter change allows the system to accommodate the sinkage effect in soft tissues by measuring the actual penetration depth rather than relying on surface-level indentation that becomes inaccurate when surrounding tissue compresses.

Inventive Principle:

Principle #35Parameter changes

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 high-accuracy hardness measurements regardless of sinkage, providing a more precise and cost-effective solution compared to traditional methods by using a magnetic sensor and processing techniques to calculate the spring constant.

Implementation Method 1

a magnetic sensor (19) which outputs electric voltage information based on a magnetic field

Methodology Applied

Scientific EffectMagnetic field detection: Electromagnetic Induction

Implementation Method 2

an acceleration sensor (13) which outputs acceleration information

Methodology Applied

Scientific EffectAcceleration sensing: Accelerometer

Data Source

PatentUS9055893B2Degree of hardness measurement system and degree of hardness measurement method

Publication Date: 2015.06.16 MAXELL LTD

AI summary

For measuring hardness of an object, a measurement apparatus is pushed against the object and a degree of hardness calculation system calculates hardness based on information from the measurement apparatus. The measurement apparatus includes an acceleration sensor which outputs first information of acceleration of a contact area of the measurement apparatus, and a second sensor, such as a magnetic sensor or a pressure sensor, which outputs second information based on pressure applied to the contact area. The degree of hardness calculation system generates a second-derivative waveform by twice differentiating a waveform based on the output of the second sensor, compares the second-derivative waveform and the information of acceleration from the acceleration sensor, and calculates hardness of the object based on the comparison result.