Closed-Loop FES Control of a Hybrid Exoskeleton during Sit-to-Stand Exercises: Concept and First Evaluation

Lyu, Chenglin; Morim, Pedro Truppel; Penzlin, Bernhard; Röhren, Felix; Bergmann, Lukas; von Platen, Philip; Bollheimer, Cornelius; Leonhardt, Steffen; Ngo, Chuong

doi:10.3390/act12080316

Open AccessArticle

Closed-Loop FES Control of a Hybrid Exoskeleton during Sit-to-Stand Exercises: Concept and First Evaluation

by

Chenglin Lyu

¹

,

Pedro Truppel Morim

¹,

Bernhard Penzlin

^1,2

,

Felix Röhren

¹,

Lukas Bergmann

¹

,

Philip von Platen

¹,

Cornelius Bollheimer

³,

Steffen Leonhardt

^1,*

and

Chuong Ngo

^1,*

¹

Chair for Medical Information Technology, Helmholtz Institute for Biomedical Engineering, RWTH Aachen University, Pauwelsstr. 20, D-52074 Aachen, Germany

²

EXYTRON GmbH, Kurt-Dunkelmann-Straße 5, D-18057 Rostock, Germany

³

Department of Geriatric Medicine, Faculty of Medicine, RWTH Aachen University Hospital, Morillenhang 27, D-52074 Aachen, Germany

^*

Authors to whom correspondence should be addressed.

Actuators 2023, 12(8), 316; https://doi.org/10.3390/act12080316

Submission received: 21 June 2023 / Revised: 24 July 2023 / Accepted: 3 August 2023 / Published: 5 August 2023

Download

Browse Figures

Review Reports Versions Notes

Abstract

Rehabilitation of paralysis caused by a stroke or a spinal cord injury remains a complex and time-consuming task. This work proposes a hybrid exoskeleton approach combining a traditional exoskeleton and functional electrical stimulation (FES) as a promising method in rehabilitation. However, hybrid exoskeletons with a closed-loop FES control strategy are functionally challenging to achieve and have not been reported often. Therefore, this study aimed to investigate a powered lower-limb exoskeleton with a closed-loop FES control for Sit-to-Stand (STS) movements. A body motion capture system was applied to record precise hip and knee trajectories of references for establishing the human model. A closed-loop control strategy with allocation factors is proposed featuring a two-layer cascaded proportional–integral–derivative (PID) controller for both FES and exoskeleton control. Experiments were performed on two participants to examine the feasibility of the hybrid exoskeleton and the closed-loop FES control. Both open- and closed-loop FES control showed the desired performance with a relatively low root-mean-squared error (max 1.3

^{\circ}

in open-loop and max 4.1

^{\circ}

in closed-loop) in hip and knee trajectories. Notably, the closed-loop FES control strategy can achieve the same performance with nearly 60% of the electrical power input compared to the open-loop control, which reduced muscle fatigue and improved robustness during the training. This study provides novel insights into body motion capture application and proposes a closed-loop FES control for hybrid exoskeletons.

Keywords: functional electrical stimulation (FES); exoskeleton; hybrid control; body motion capture

Share and Cite

MDPI and ACS Style

Lyu, C.; Morim, P.T.; Penzlin, B.; Röhren, F.; Bergmann, L.; von Platen, P.; Bollheimer, C.; Leonhardt, S.; Ngo, C. Closed-Loop FES Control of a Hybrid Exoskeleton during Sit-to-Stand Exercises: Concept and First Evaluation. Actuators 2023, 12, 316. https://doi.org/10.3390/act12080316

AMA Style

Lyu C, Morim PT, Penzlin B, Röhren F, Bergmann L, von Platen P, Bollheimer C, Leonhardt S, Ngo C. Closed-Loop FES Control of a Hybrid Exoskeleton during Sit-to-Stand Exercises: Concept and First Evaluation. Actuators. 2023; 12(8):316. https://doi.org/10.3390/act12080316

Chicago/Turabian Style

Lyu, Chenglin, Pedro Truppel Morim, Bernhard Penzlin, Felix Röhren, Lukas Bergmann, Philip von Platen, Cornelius Bollheimer, Steffen Leonhardt, and Chuong Ngo. 2023. "Closed-Loop FES Control of a Hybrid Exoskeleton during Sit-to-Stand Exercises: Concept and First Evaluation" Actuators 12, no. 8: 316. https://doi.org/10.3390/act12080316

APA Style

Lyu, C., Morim, P. T., Penzlin, B., Röhren, F., Bergmann, L., von Platen, P., Bollheimer, C., Leonhardt, S., & Ngo, C. (2023). Closed-Loop FES Control of a Hybrid Exoskeleton during Sit-to-Stand Exercises: Concept and First Evaluation. Actuators, 12(8), 316. https://doi.org/10.3390/act12080316

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Menu

Closed-Loop FES Control of a Hybrid Exoskeleton during Sit-to-Stand Exercises: Concept and First Evaluation

Abstract

Share and Cite

Article Metrics

Article Access Statistics

Further Information

Guidelines

MDPI Initiatives

Follow MDPI