Design of a 2DoF Ankle Exoskeleton with a Polycentric Structure and a Bi-Directional Tendon-Driven Actuator Controlled Using a PID Neural Network

Lower limb exoskeleton robots help with walking movements through mechanical force, by identifying the wearer’s walking intention. When the exoskeleton robot is lightweight and comfortable to wear, the stability of walking increases, and energy can be used efficiently. However, because it is difficu...

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Main Authors: Taehoon Lee, Inwoo Kim, Yoon Su Baek
Format: Article
Language:English
Published: MDPI AG 2021-01-01
Series:Actuators
Subjects:
Online Access:https://www.mdpi.com/2076-0825/10/1/9
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spelling doaj-8fa5cf81327d44149bbff0ba8d7217af2021-01-05T00:02:23ZengMDPI AGActuators2076-08252021-01-01109910.3390/act10010009Design of a 2DoF Ankle Exoskeleton with a Polycentric Structure and a Bi-Directional Tendon-Driven Actuator Controlled Using a PID Neural NetworkTaehoon Lee0Inwoo Kim1Yoon Su Baek2Department of Mechanical Engineering, Yonsei University, Seoul 03722, KoreaDepartment of Mechanical Engineering, Yonsei University, Seoul 03722, KoreaDepartment of Mechanical Engineering, Yonsei University, Seoul 03722, KoreaLower limb exoskeleton robots help with walking movements through mechanical force, by identifying the wearer’s walking intention. When the exoskeleton robot is lightweight and comfortable to wear, the stability of walking increases, and energy can be used efficiently. However, because it is difficult to implement the complex anatomical movements of the human body, most are designed simply. Due to this, misalignment between the human and robot movement causes the wearer to feel uncomfortable, and the stability of walking is reduced. In this paper, we developed a two degrees of freedom (2DoF) ankle exoskeleton robot with a subtalar joint and a talocrural joint, applying a four-bar linkage to realize the anatomical movement of a simple 1DoF structure mainly used for ankles. However, bidirectional tendon-driven actuators (BTDAs) do not consider the difference in a length change of both cables due to dorsiflexion (DF) and plantar flexion (PF) during walking, causing misalignment. To solve this problem, a BTDA was developed by considering the length change of both cables. Cable-driven actuators and exoskeleton robot systems create uncertainty. Accordingly, adaptive control was performed with a proportional-integral-differential neural network (PIDNN) controller to minimize system uncertainty.https://www.mdpi.com/2076-0825/10/1/92DoF ankle exoskeleton robotpolycentric structurebidirectional tendon-driven actuatorPID neural network controller (PIDNN)misalignment
collection DOAJ
language English
format Article
sources DOAJ
author Taehoon Lee
Inwoo Kim
Yoon Su Baek
spellingShingle Taehoon Lee
Inwoo Kim
Yoon Su Baek
Design of a 2DoF Ankle Exoskeleton with a Polycentric Structure and a Bi-Directional Tendon-Driven Actuator Controlled Using a PID Neural Network
Actuators
2DoF ankle exoskeleton robot
polycentric structure
bidirectional tendon-driven actuator
PID neural network controller (PIDNN)
misalignment
author_facet Taehoon Lee
Inwoo Kim
Yoon Su Baek
author_sort Taehoon Lee
title Design of a 2DoF Ankle Exoskeleton with a Polycentric Structure and a Bi-Directional Tendon-Driven Actuator Controlled Using a PID Neural Network
title_short Design of a 2DoF Ankle Exoskeleton with a Polycentric Structure and a Bi-Directional Tendon-Driven Actuator Controlled Using a PID Neural Network
title_full Design of a 2DoF Ankle Exoskeleton with a Polycentric Structure and a Bi-Directional Tendon-Driven Actuator Controlled Using a PID Neural Network
title_fullStr Design of a 2DoF Ankle Exoskeleton with a Polycentric Structure and a Bi-Directional Tendon-Driven Actuator Controlled Using a PID Neural Network
title_full_unstemmed Design of a 2DoF Ankle Exoskeleton with a Polycentric Structure and a Bi-Directional Tendon-Driven Actuator Controlled Using a PID Neural Network
title_sort design of a 2dof ankle exoskeleton with a polycentric structure and a bi-directional tendon-driven actuator controlled using a pid neural network
publisher MDPI AG
series Actuators
issn 2076-0825
publishDate 2021-01-01
description Lower limb exoskeleton robots help with walking movements through mechanical force, by identifying the wearer’s walking intention. When the exoskeleton robot is lightweight and comfortable to wear, the stability of walking increases, and energy can be used efficiently. However, because it is difficult to implement the complex anatomical movements of the human body, most are designed simply. Due to this, misalignment between the human and robot movement causes the wearer to feel uncomfortable, and the stability of walking is reduced. In this paper, we developed a two degrees of freedom (2DoF) ankle exoskeleton robot with a subtalar joint and a talocrural joint, applying a four-bar linkage to realize the anatomical movement of a simple 1DoF structure mainly used for ankles. However, bidirectional tendon-driven actuators (BTDAs) do not consider the difference in a length change of both cables due to dorsiflexion (DF) and plantar flexion (PF) during walking, causing misalignment. To solve this problem, a BTDA was developed by considering the length change of both cables. Cable-driven actuators and exoskeleton robot systems create uncertainty. Accordingly, adaptive control was performed with a proportional-integral-differential neural network (PIDNN) controller to minimize system uncertainty.
topic 2DoF ankle exoskeleton robot
polycentric structure
bidirectional tendon-driven actuator
PID neural network controller (PIDNN)
misalignment
url https://www.mdpi.com/2076-0825/10/1/9
work_keys_str_mv AT taehoonlee designofa2dofankleexoskeletonwithapolycentricstructureandabidirectionaltendondrivenactuatorcontrolledusingapidneuralnetwork
AT inwookim designofa2dofankleexoskeletonwithapolycentricstructureandabidirectionaltendondrivenactuatorcontrolledusingapidneuralnetwork
AT yoonsubaek designofa2dofankleexoskeletonwithapolycentricstructureandabidirectionaltendondrivenactuatorcontrolledusingapidneuralnetwork
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