Earable Ω (OMEGA): A Novel Clenching Interface Using Ear Canal Sensing for Human Metacarpophalangeal Joint Control by Functional Electrical Stimulation

(1) Background: A mouth-free interface is required for functional electrical stimulation (FES) in people with spinal cord injuries. We developed a novel system for clenching the human metacarpophalangeal (MP) joint using an earphone-type ear canal movement sensor. Experiments to control joint angle...

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Main Authors: Kazuhiro Matsui, Yuya Suzuki, Keita Atsuumi, Miwa Nagai, Shotaro Ohno, Hiroaki Hirai, Atsushi Nishikawa, Kazuhiro Taniguchi
Format: Article
Language:English
Published: MDPI AG 2022-09-01
Series:Sensors
Subjects:
Online Access:https://www.mdpi.com/1424-8220/22/19/7412
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author Kazuhiro Matsui
Yuya Suzuki
Keita Atsuumi
Miwa Nagai
Shotaro Ohno
Hiroaki Hirai
Atsushi Nishikawa
Kazuhiro Taniguchi
author_facet Kazuhiro Matsui
Yuya Suzuki
Keita Atsuumi
Miwa Nagai
Shotaro Ohno
Hiroaki Hirai
Atsushi Nishikawa
Kazuhiro Taniguchi
author_sort Kazuhiro Matsui
collection DOAJ
description (1) Background: A mouth-free interface is required for functional electrical stimulation (FES) in people with spinal cord injuries. We developed a novel system for clenching the human metacarpophalangeal (MP) joint using an earphone-type ear canal movement sensor. Experiments to control joint angle and joint stiffness were performed using the developed system. (2) Methods: The proposed FES used an equilibrium point control signal and stiffness control signal: electrical agonist–antagonist ratio and electrical agonist–antagonist sum. An angle sensor was used to acquire the joint angle, and system identification was utilized to measure joint stiffness using the external force of a robot arm. Each experiment included six and five subjects, respectively. (3) Results: While the joint angle could be controlled well by clenching with some hysteresis and delay in three subjects, it could not be controlled relatively well after hyperextension in the other subjects, which revealed a calibration problem and a change in the characteristics of the human MP joint caused by hyperextension. The joint stiffness increased with the clenching amplitude in five subjects. In addition, the results indicated that viscosity can be controlled. (4) Conclusions: The developed system can control joint angle and stiffness. In future research, we will develop a method to show that this system can control the equilibrium point and stiffness simultaneously.
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spelling doaj.art-51c23af9a62041a8a0670a0ae1ae3bf02023-11-23T21:48:46ZengMDPI AGSensors1424-82202022-09-012219741210.3390/s22197412Earable Ω (OMEGA): A Novel Clenching Interface Using Ear Canal Sensing for Human Metacarpophalangeal Joint Control by Functional Electrical StimulationKazuhiro Matsui0Yuya Suzuki1Keita Atsuumi2Miwa Nagai3Shotaro Ohno4Hiroaki Hirai5Atsushi Nishikawa6Kazuhiro Taniguchi7Graduate School of Engineering Science, Osaka University, Toyonaka 560-8531, Osaka, JapanGraduate School of Engineering Science, Osaka University, Toyonaka 560-8531, Osaka, JapanGraduate School of Engineering Science, Osaka University, Toyonaka 560-8531, Osaka, JapanGraduate School of Engineering Science, Osaka University, Toyonaka 560-8531, Osaka, JapanGraduate School of Engineering Science, Osaka University, Toyonaka 560-8531, Osaka, JapanGraduate School of Engineering Science, Osaka University, Toyonaka 560-8531, Osaka, JapanGraduate School of Engineering Science, Osaka University, Toyonaka 560-8531, Osaka, JapanGraduate School of Engineering Science, Osaka University, Toyonaka 560-8531, Osaka, Japan(1) Background: A mouth-free interface is required for functional electrical stimulation (FES) in people with spinal cord injuries. We developed a novel system for clenching the human metacarpophalangeal (MP) joint using an earphone-type ear canal movement sensor. Experiments to control joint angle and joint stiffness were performed using the developed system. (2) Methods: The proposed FES used an equilibrium point control signal and stiffness control signal: electrical agonist–antagonist ratio and electrical agonist–antagonist sum. An angle sensor was used to acquire the joint angle, and system identification was utilized to measure joint stiffness using the external force of a robot arm. Each experiment included six and five subjects, respectively. (3) Results: While the joint angle could be controlled well by clenching with some hysteresis and delay in three subjects, it could not be controlled relatively well after hyperextension in the other subjects, which revealed a calibration problem and a change in the characteristics of the human MP joint caused by hyperextension. The joint stiffness increased with the clenching amplitude in five subjects. In addition, the results indicated that viscosity can be controlled. (4) Conclusions: The developed system can control joint angle and stiffness. In future research, we will develop a method to show that this system can control the equilibrium point and stiffness simultaneously.https://www.mdpi.com/1424-8220/22/19/7412functional electrical stimulationear canal sensorclenchingspinal cord injuryfinger
spellingShingle Kazuhiro Matsui
Yuya Suzuki
Keita Atsuumi
Miwa Nagai
Shotaro Ohno
Hiroaki Hirai
Atsushi Nishikawa
Kazuhiro Taniguchi
Earable Ω (OMEGA): A Novel Clenching Interface Using Ear Canal Sensing for Human Metacarpophalangeal Joint Control by Functional Electrical Stimulation
Sensors
functional electrical stimulation
ear canal sensor
clenching
spinal cord injury
finger
title Earable Ω (OMEGA): A Novel Clenching Interface Using Ear Canal Sensing for Human Metacarpophalangeal Joint Control by Functional Electrical Stimulation
title_full Earable Ω (OMEGA): A Novel Clenching Interface Using Ear Canal Sensing for Human Metacarpophalangeal Joint Control by Functional Electrical Stimulation
title_fullStr Earable Ω (OMEGA): A Novel Clenching Interface Using Ear Canal Sensing for Human Metacarpophalangeal Joint Control by Functional Electrical Stimulation
title_full_unstemmed Earable Ω (OMEGA): A Novel Clenching Interface Using Ear Canal Sensing for Human Metacarpophalangeal Joint Control by Functional Electrical Stimulation
title_short Earable Ω (OMEGA): A Novel Clenching Interface Using Ear Canal Sensing for Human Metacarpophalangeal Joint Control by Functional Electrical Stimulation
title_sort earable ω omega a novel clenching interface using ear canal sensing for human metacarpophalangeal joint control by functional electrical stimulation
topic functional electrical stimulation
ear canal sensor
clenching
spinal cord injury
finger
url https://www.mdpi.com/1424-8220/22/19/7412
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