Experiences in the Creation of an

Electromyography Database

to Help Hand Amputated Persons

Manfredo Atzori, Arjan Gijsberts, Simone Heynen,

Anne-Gabrielle Mittaz Hager, Claudio Castellini,

Barbara Caputo, Henning Müller

Overview

• EMG and prosthetics

• Motivations and goals

• Acquisition setup and sensors

• Hand movements

• Results

– Electrodes

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Electromyography

• Electromyography (EMG) is the

measurement of electrical activity

that is created by muscle contractions

• The signal path

– Originates in a motor neuron

– Travels to the target muscle(s)

– Starts a series of electrochemical changes that lead

to an action potential

– Can be detected by one or more electrodes

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EMG controlled prosthetics

• 2-3 degrees of freedom

• Few programmed movements

• Very coarse force control

• No dexterous control

• No natural control

• Long training times

• This is in contrast to recent advances

in mechatronics!

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Motivation for the work

• NO large scale public sEMG databases, only

private ones

– (Fukuda, 2003; Tsuji 1993; Ferguson, 2002; Zecca,

2002; Chan, 2005; Sebelius, 2005; Castellini, 2008;

Jiang, 2009; Tenore, 2009; Castellini, 2009)

• NO common sEMG acquisition protocol

• NO common sEMG storage protocol

• NO Clinical Data Correlation Evaluation

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Goals

• Creation and refinement of an acquisition protocol

• Acquisition of a database

• Public release of the database

• Worldwide test of classification algorithms using the

same data and setup

– Improve quality of classification

– Transfer this knowledge to build better prostheses

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Acquisition setup

• Laptop: Dell Latitude E5520

• Digital Acquisition Card: National

Instruments 6023E

• sEMG Electrodes: 10 double-differential

Otto Bock 13E200

• Printed Circuit Board, Cables &

Connectors

• Data Glove 22 sensors Cyberglove II

(Cyberglove Systems)

• Inclinometer: Kübler 8.IS40.2341

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Sensor setup

• 8 equally spaced electrodes

• 2 electrodes on finger flexor and extensor muscles

• Two axes inclinometer

• Data glove

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Hand movements

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Hato, 2004

Sebelius, 2005

Farrel, 2008

Crawford, 2005

Exercise 1 12 movements

Exercise 2 17 movements

Training Training

More movements

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Feix, 2008 DASH Score

Exercise 3 23 movements

Objects are simple tools to make

the protocol easy to reproduce

everywhere.

Web-based database (http://ninapro.hevs.ch/)

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Data stored

• XML file with clinical and experimental information

• Unprocessed data (sEMG, Cyberglove,

Inclinometer, Movie)

• Preview picture for each exercise

• Picture of the arm without the acquisition setup

• Picture of the arm with the acquisition setup

• Currently stored: 27 intact subjects, 1 amputated

subject, several recordings for a few

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Gender 21 males 7 females

Handedness 26 right handed 2 left handed

Age 28.1 ± 3.4 years

Electrode experiences

• Double differential potential

– Good signal to noise ratio

• Excellent comfort (no cleaning/

shaving)

• Classification results in

accordance with the scientific

literature (~7-20%)

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Two types of electrodes tested

• Otto Bock 13E200

– Root mean square rectification

– High pass filtering

– Sampling frequency: 100 Hz

• Delsys Trigno

– Raw signal

– Sampling frequency: 2KHz

– Wi-fi

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L. F. Law et al., 2010

L. F. Law et al., 2010

Acquisition experiences (amputated)

• Dry the stump before the experiment

• Need of longer breaks between the exercises

• Modification of the instructions avoiding the concept

of an imaginary limb

• Elimination of a few movements from the protocol

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Acquisition experience (non amputated)

• Difficulty to place electrodes exactly in the same

position for subjects

– Need of spatial normalization as anatomy changes

and positions are not 100% stable

• Validation of the acquisition protocol with small

changes

– Function check of electrodes is required

– System needs to limit artifacts caused by users

• Removal of a few functional movements showing

high inter subject differences

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Conclusions

• Test and improvement of the acquisition setup

– Portable, based on research and industrial needs

• Test and improvement of the acquisition protocol

– Complete and easy to be reproduced

– Fixed several practical aspects

• Test and improvement of the hand movements

– 52, selected from robotics and medical literature

• Test of acquired sEMG signals (classification)

– Good SNR ratio

– Results in line with the scientific literature

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Questions, contacts?

• For more information:

• http://www.idiap.ch/project/ninapro/

• http://ninapro.hevs.ch

• Contacts:

• manfredo.atzori@gmail.com

• henning.mueller@hevs.ch

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