EMG Signal Separation Using Vectorial Propagation Analysis

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Solution Overview

Problem

Current EMG measurement techniques face challenges in distinguishing between useful and interference signals, particularly in areas with muscle superimposition, leading to uncertainty in identifying the physiological origin of signals and reduced robustness in measurements.

Innovation Solution

A method involving the use of at least three electrodes placed on different axes to detect EMG signals, measure voltage along these axes, and determine the muscular direction of propagation, which helps in separating useful and interference signals and identifying the signal-causing muscle.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If multiple EMG channels are used to cover several muscle groups, then the measurement area increases, but the ability to unambiguously assign measurement areas to single muscles decreases due to muscle overlap

Engineering Contradiction:
Improvemeasurement areaVSAvoidsignal source identification
Core Design Contradiction:
Area of stationary objectVSMeasurement precision

Solution Approach 1:

The patent extends the measurement from two-dimensional signal strength mapping to three-dimensional vector field analysis by incorporating propagation direction information. This additional dimension enables differentiation of superimposed muscles through their distinct propagation directions, resolving the ambiguity caused by muscle overlap while maintaining comprehensive coverage

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Device complexity

If only signal strength between electrodes is measured, then the measurement method remains simple, but the information content remains limited and cannot differentiate contractions of different superimposed muscles

Engineering Contradiction:
Improvemeasurement methodVSAvoidinformation content
Core Design Contradiction:
Device complexityVSLoss of information

Solution Approach 1:

The patent adds the propagation direction dimension to the traditional signal strength measurement, transforming scalar measurements into vector measurements. This enables the system to differentiate between superimposed muscles without significantly increasing device complexity, as the same electrode array can provide both magnitude and direction information through vector field analysis

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Adaptability or versatility

If EMG measurements are performed in areas with muscle superimposition, then comprehensive muscle coverage is achieved, but the robustness of measurements decreases due to inability to distinguish signal origins

Engineering Contradiction:
Improvemuscle coverageVSAvoidmeasurement robustness
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

By incorporating propagation direction as an additional dimension, the patent enables reliable source identification even in areas with muscle superimposition. The vector field approach allows differentiation of multiple muscle contributions through their distinct directional characteristics, maintaining measurement robustness while achieving comprehensive muscle coverage

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 enhances the robustness of EMG measurements, improves the distinction between actual muscle contractions and interference, and provides more detailed information by determining the plausible signal origin, thus increasing immunity to interference.

Implementation Method 1

EMG records the summed potential of all active muscle fibers, measuring the muscle action potentials by differential voltage measurement

Methodology Applied
Scientific EffectDifferential voltage measurement: Electric Field

Implementation Method 2

When a muscle is stimulated, an action potential is generated in the muscle fibers, which, due to the anisotropic conductivity properties of a muscle fiber, propagates preferentially in the direction of the fiber

Methodology Applied
Scientific EffectAnisotropic conductivity: Conduction (electrical)

Data Source

PatentEP4162878A1Method for vectorial acquisition and processing of electromyographic signals
Publication Date: 2023.04.12 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV
  • EP4162878A1 patent drawingFigure 1A~1B
  • EP4162878A1 patent drawingFigure 2A~2B
  • EP4162878A1 patent drawingFigure 3

AI summary

A method for separating useful and unwanted signals in an electromyographic (EMG) measurement and/or for determining the signal-generating muscle in an electrically active region of muscles, the use of the method for EMG diagnostics, for controlling prostheses, for training muscles, or for controlling computer programs and/or computer games, and a computer-implemented method, a computer program product, a computer-readable storage medium, and a device for separating useful and unwanted signals in an EMG measurement and/or for determining the signal-generating muscle in an electrically active region of muscles are provided.