Drift-Compensated Infant Scale Using Wheatstone Bridge Resistor Measurements

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Solution Overview

Problem

Electronic scales using strain gauges face accuracy issues due to electrical drift, requiring frequent taring processes that can be time-consuming and disruptive, especially in sensitive environments like neonatal units.

Innovation Solution

A method to obtain drift-compensated weight measurements by determining and subtracting a drift voltage from the output voltage of a Wheatstone bridge in a strain gauge, using individual voltage measurements across each resistor to correct for electrical drift, thereby reducing the need for frequent taring.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If frequent taring is performed to maintain measurement accuracy, then measurement precision is improved, but loss of time and productivity deteriorate

Engineering Contradiction:

Improveweight measurement accuracyVSAvoidtime for taring process

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces the manual mechanical taring process with an automated electrical compensation system. The drift voltage is measured electrically across the strain gauge resistors and subtracted from the output signal, eliminating the need for manual intervention and maintaining measurement accuracy continuously without time loss.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system performs self-correction by automatically measuring the drift voltage across the strain gauge resistors and compensating for it in real-time. The scale autonomously maintains accuracy through continuous drift monitoring and subtraction, without requiring external user intervention for taring.

Inventive Principle:

Principle #25Self-service

2Measurement precision

If frequent taring is performed to maintain measurement accuracy, then measurement precision is improved, but device complexity increases

Engineering Contradiction:

Improveweight measurement accuracyVSAvoidtaring process complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the complex manual taring procedure with a simple electrical measurement and subtraction process. By measuring drift voltage directly across the existing strain gauge resistors and subtracting it from the output, the system eliminates the need for complex calibration procedures while maintaining accuracy.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system continuously monitors the drift voltage across the strain gauge resistors and feeds this information back to the compensation circuit, which automatically adjusts the output signal. This closed-loop feedback mechanism maintains accuracy without requiring complex manual intervention or multiple calibration steps.

Inventive Principle:

Principle #23Feedback

3Measurement precision

If frequent taring is performed to maintain measurement accuracy, then measurement precision is improved, but object-affected harmful factors worsen

Engineering Contradiction:

Improveweight measurement accuracyVSAvoidinfant agitation and infection risk

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the disruptive manual taring process with a non-intrusive electrical compensation system. The drift voltage is measured and compensated electrically without requiring physical contact or movement of the infant, thereby eliminating agitation and infection risks while maintaining measurement accuracy.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system provides continuous drift compensation by continuously measuring the voltage across the strain gauge resistors and subtracting the drift component in real-time. This continuous automated correction maintains accuracy without interrupting the measurement process or requiring movement of the infant on the scale.

Inventive Principle:

Principle #20Continuity of useful 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 approach provides more accurate and continuous weight measurements, reducing the frequency of taring and minimizing agitation and infection risk for infants, while maintaining high tracking and medication administration accuracy.

Implementation Method 1

Strain gauges are used in a variety of applications to measure changes in a force, such as weight or pressure, applied to an object to which they are coupled

Methodology Applied

Scientific EffectPiezoresistive effect: Piezoresistive Effect

Implementation Method 2

The four resistive strain gauges are connected to form a Wheatstone bridge

Methodology Applied

Scientific EffectWheatstone bridge: Wheatstone Bridge

Data Source

PatentEP3881036B1Methods and system for obtaining a force measurement with reduced drift effects

Publication Date: 2023.10.18 GENERAL ELECTRIC CO

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AI summary

Various methods and systems are provided for a drift-compensated force measurement. In one example, a method includes obtaining a single output voltage measurement from a strain gauge of an infant scale, the single output voltage reflective of a weight applied to the scale; obtaining a voltage measurement across each of four resistors of the strain gauge to determine four separate voltage measurements and determining a drift voltage based on the four separate voltage measurements; and outputting a corrected weight value determined based on a difference between the single output voltage and the drift voltage.