A Self-Adaptive-Coefficient-Double-Power Sliding Mode Control Method for Lower Limb Rehabilitation Exoskeleton Robot

Lower limb rehabilitation exoskeleton robots have the characteristics of nonlinearity and strong coupling, and they are easily disturbed during operation by environmental factors. Thus, an accurate dynamic model of the robot is difficult to obtain, and achieving trajectory tracking control of the ro...

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Autores principales: Yuepeng Zhang, Guangzhong Cao, Wenzhou Li, Jiangcheng Chen, Linglong Li, Dongfeng Diao
Formato: article
Lenguaje:EN
Publicado: MDPI AG 2021
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spelling oai:doaj.org-article:4d4802635d274ec081ec54d95be629a82021-11-11T15:21:12ZA Self-Adaptive-Coefficient-Double-Power Sliding Mode Control Method for Lower Limb Rehabilitation Exoskeleton Robot10.3390/app1121103292076-3417https://doaj.org/article/4d4802635d274ec081ec54d95be629a82021-11-01T00:00:00Zhttps://www.mdpi.com/2076-3417/11/21/10329https://doaj.org/toc/2076-3417Lower limb rehabilitation exoskeleton robots have the characteristics of nonlinearity and strong coupling, and they are easily disturbed during operation by environmental factors. Thus, an accurate dynamic model of the robot is difficult to obtain, and achieving trajectory tracking control of the robot is also difficult. In this article, a self-adaptive-coefficient double-power sliding mode control method is proposed to overcome the difficulty of tracking the robot trajectory. The method combines an estimated dynamic model with sliding mode control. A nonlinear control law was designed based on the robot dynamics model and computational torque method, and a compensation term of control law based on double-power reaching law was introduced to reduce the disturbance from model error and environmental factors. The self-adaptive coefficient of the compensation term of the control law was designed to adaptively adjust the compensation term to improve the anti-interference ability of the robot. The simulation and experiment results show that the proposed method effectively improves the trajectory tracking accuracy and anti-interference ability of the robot. Compared with the traditional computed torque method, the proposed method decreases the tracking error by more than 71.77%. The maximum absolute error of the hip joint and knee joint remained below 0.55° and 1.65°, respectively, in the wearable experiment of the robot.Yuepeng ZhangGuangzhong CaoWenzhou LiJiangcheng ChenLinglong LiDongfeng DiaoMDPI AGarticlelower limb rehabilitation exoskeleton robottrajectory trackingestimated dynamic modelsliding mode controlself-adaptive-coefficient-double-power reaching lawTechnologyTEngineering (General). Civil engineering (General)TA1-2040Biology (General)QH301-705.5PhysicsQC1-999ChemistryQD1-999ENApplied Sciences, Vol 11, Iss 10329, p 10329 (2021)
institution DOAJ
collection DOAJ
language EN
topic lower limb rehabilitation exoskeleton robot
trajectory tracking
estimated dynamic model
sliding mode control
self-adaptive-coefficient-double-power reaching law
Technology
T
Engineering (General). Civil engineering (General)
TA1-2040
Biology (General)
QH301-705.5
Physics
QC1-999
Chemistry
QD1-999
spellingShingle lower limb rehabilitation exoskeleton robot
trajectory tracking
estimated dynamic model
sliding mode control
self-adaptive-coefficient-double-power reaching law
Technology
T
Engineering (General). Civil engineering (General)
TA1-2040
Biology (General)
QH301-705.5
Physics
QC1-999
Chemistry
QD1-999
Yuepeng Zhang
Guangzhong Cao
Wenzhou Li
Jiangcheng Chen
Linglong Li
Dongfeng Diao
A Self-Adaptive-Coefficient-Double-Power Sliding Mode Control Method for Lower Limb Rehabilitation Exoskeleton Robot
description Lower limb rehabilitation exoskeleton robots have the characteristics of nonlinearity and strong coupling, and they are easily disturbed during operation by environmental factors. Thus, an accurate dynamic model of the robot is difficult to obtain, and achieving trajectory tracking control of the robot is also difficult. In this article, a self-adaptive-coefficient double-power sliding mode control method is proposed to overcome the difficulty of tracking the robot trajectory. The method combines an estimated dynamic model with sliding mode control. A nonlinear control law was designed based on the robot dynamics model and computational torque method, and a compensation term of control law based on double-power reaching law was introduced to reduce the disturbance from model error and environmental factors. The self-adaptive coefficient of the compensation term of the control law was designed to adaptively adjust the compensation term to improve the anti-interference ability of the robot. The simulation and experiment results show that the proposed method effectively improves the trajectory tracking accuracy and anti-interference ability of the robot. Compared with the traditional computed torque method, the proposed method decreases the tracking error by more than 71.77%. The maximum absolute error of the hip joint and knee joint remained below 0.55° and 1.65°, respectively, in the wearable experiment of the robot.
format article
author Yuepeng Zhang
Guangzhong Cao
Wenzhou Li
Jiangcheng Chen
Linglong Li
Dongfeng Diao
author_facet Yuepeng Zhang
Guangzhong Cao
Wenzhou Li
Jiangcheng Chen
Linglong Li
Dongfeng Diao
author_sort Yuepeng Zhang
title A Self-Adaptive-Coefficient-Double-Power Sliding Mode Control Method for Lower Limb Rehabilitation Exoskeleton Robot
title_short A Self-Adaptive-Coefficient-Double-Power Sliding Mode Control Method for Lower Limb Rehabilitation Exoskeleton Robot
title_full A Self-Adaptive-Coefficient-Double-Power Sliding Mode Control Method for Lower Limb Rehabilitation Exoskeleton Robot
title_fullStr A Self-Adaptive-Coefficient-Double-Power Sliding Mode Control Method for Lower Limb Rehabilitation Exoskeleton Robot
title_full_unstemmed A Self-Adaptive-Coefficient-Double-Power Sliding Mode Control Method for Lower Limb Rehabilitation Exoskeleton Robot
title_sort self-adaptive-coefficient-double-power sliding mode control method for lower limb rehabilitation exoskeleton robot
publisher MDPI AG
publishDate 2021
url https://doaj.org/article/4d4802635d274ec081ec54d95be629a8
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