1
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Rosenberg MC, Proctor JL, Steele KM. Quantifying changes in individual-specific template-based representations of center-of-mass dynamics during walking with ankle exoskeletons using Hybrid-SINDy. Sci Rep 2024; 14:1031. [PMID: 38200078 PMCID: PMC10781730 DOI: 10.1038/s41598-023-50999-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Accepted: 12/28/2023] [Indexed: 01/12/2024] Open
Abstract
Ankle exoskeletons alter whole-body walking mechanics, energetics, and stability by altering center-of-mass (CoM) motion. Controlling the dynamics governing CoM motion is, therefore, critical for maintaining efficient and stable gait. However, how CoM dynamics change with ankle exoskeletons is unknown, and how to optimally model individual-specific CoM dynamics, especially in individuals with neurological injuries, remains a challenge. Here, we evaluated individual-specific changes in CoM dynamics in unimpaired adults and one individual with post-stroke hemiparesis while walking in shoes-only and with zero-stiffness and high-stiffness passive ankle exoskeletons. To identify optimal sets of physically interpretable mechanisms describing CoM dynamics, termed template signatures, we leveraged hybrid sparse identification of nonlinear dynamics (Hybrid-SINDy), an equation-free data-driven method for inferring sparse hybrid dynamics from a library of candidate functional forms. In unimpaired adults, Hybrid-SINDy automatically identified spring-loaded inverted pendulum-like template signatures, which did not change with exoskeletons (p > 0.16), except for small changes in leg resting length (p < 0.001). Conversely, post-stroke paretic-leg rotary stiffness mechanisms increased by 37-50% with zero-stiffness exoskeletons. While unimpaired CoM dynamics appear robust to passive ankle exoskeletons, how neurological injuries alter exoskeleton impacts on CoM dynamics merits further investigation. Our findings support Hybrid-SINDy's potential to discover mechanisms describing individual-specific CoM dynamics with assistive devices.
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Affiliation(s)
- Michael C Rosenberg
- Department of Mechanical Engineering, University of Washington, Seattle, USA.
| | - Joshua L Proctor
- Department of Mechanical Engineering, University of Washington, Seattle, USA
- Department of Applied Mathematics, University of Washington, Seattle, USA
| | - Katherine M Steele
- Department of Mechanical Engineering, University of Washington, Seattle, USA
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2
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Lora-Millan JS, Sanchez-Cuesta FJ, Romero JP, Moreno JC, Rocon E. Robotic exoskeleton embodiment in post-stroke hemiparetic patients: an experimental study about the integration of the assistance provided by the REFLEX knee exoskeleton. Sci Rep 2023; 13:22908. [PMID: 38129592 PMCID: PMC10739721 DOI: 10.1038/s41598-023-50387-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Accepted: 12/19/2023] [Indexed: 12/23/2023] Open
Abstract
Hemiparetic gait is the most common motor-disorder after stroke and, in spite of rehabilitation efforts, it is persistent in 50% of community dwelling stroke-survivors. Robotic exoskeletons have been proposed as assistive devices to support impaired joints. An example of these devices is the REFLEX knee exoskeleton, which assists the gait of hemiparetic subjects and whose action seems to be properly embodied by stroke survivors, who were able to adapt the motion of their non-assisted limbs and, therefore, reduce their compensation mechanisms. This paper presents an experimental validation carried out to deepen into the effects of REFLEX's assistance in hemiparetic subjects. Special attention was paid to the effect produced in the muscular activity as a metric to evaluate the embodiment of this technology. Significant differences were obtained at the subject level due to the assistance; however, the high dispersion of the measured outcomes avoided extracting global effects at the group level. These results highlight the need of individually tailoring the action of the robot to the individual needs of each patient to maximize the beneficial outcomes. Extra research effort should be done to elucidate the neural mechanisms involved in the embodiment of external devices by stroke survivors.
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Affiliation(s)
| | - Francisco José Sanchez-Cuesta
- Facultad de Ciencias Experimentales, Universidad Francisco de Vitoria, Pozuelo de Alarcón, Madrid, Spain
- Brain Injury and Movement Disorders Neurorehabilitation Group (GINDAT), Institute of Life Sciences, Francisco de Vitoria University, Pozuelo de Alarcón, Madrid, Spain
| | - Juan Pablo Romero
- Facultad de Ciencias Experimentales, Universidad Francisco de Vitoria, Pozuelo de Alarcón, Madrid, Spain
- Brain Injury and Movement Disorders Neurorehabilitation Group (GINDAT), Institute of Life Sciences, Francisco de Vitoria University, Pozuelo de Alarcón, Madrid, Spain
- Brain Damage Unit, Hospital Beata María Ana, Madrid, Spain
| | - Juan C Moreno
- Neural Rehabilitation Group, Cajal Institute, Spanish National Research Council (CSIC), Madrid, Spain
| | - Eduardo Rocon
- Centro de Automática y Robótica, Spanish National Research Council (CSIC), Madrid, Spain
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3
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Mahdian ZS, Wang H, Refai MIM, Durandau G, Sartori M, MacLean MK. Tapping Into Skeletal Muscle Biomechanics for Design and Control of Lower Limb Exoskeletons: A Narrative Review. J Appl Biomech 2023; 39:318-333. [PMID: 37751903 DOI: 10.1123/jab.2023-0046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 08/11/2023] [Accepted: 08/18/2023] [Indexed: 09/28/2023]
Abstract
Lower limb exoskeletons and exosuits ("exos") are traditionally designed with a strong focus on mechatronics and actuation, whereas the "human side" is often disregarded or minimally modeled. Muscle biomechanics principles and skeletal muscle response to robot-delivered loads should be incorporated in design/control of exos. In this narrative review, we summarize the advances in literature with respect to the fusion of muscle biomechanics and lower limb exoskeletons. We report methods to measure muscle biomechanics directly and indirectly and summarize the studies that have incorporated muscle measures for improved design and control of intuitive lower limb exos. Finally, we delve into articles that have studied how the human-exo interaction influences muscle biomechanics during locomotion. To support neurorehabilitation and facilitate everyday use of wearable assistive technologies, we believe that future studies should investigate and predict how exoskeleton assistance strategies would structurally remodel skeletal muscle over time. Real-time mapping of the neuromechanical origin and generation of muscle force resulting in joint torques should be combined with musculoskeletal models to address time-varying parameters such as adaptation to exos and fatigue. Development of smarter predictive controllers that steer rather than assist biological components could result in a synchronized human-machine system that optimizes the biological and electromechanical performance of the combined system.
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Affiliation(s)
- Zahra S Mahdian
- Department of Biomechanical Engineering, University of Twente, Enschede, the Netherlands
| | - Huawei Wang
- Department of Biomechanical Engineering, University of Twente, Enschede, the Netherlands
| | | | - Guillaume Durandau
- Department of Mechanical Engineering, McGill University, Montreal, QC, Canada
| | - Massimo Sartori
- Department of Biomechanical Engineering, University of Twente, Enschede, the Netherlands
| | - Mhairi K MacLean
- Department of Biomechanical Engineering, University of Twente, Enschede, the Netherlands
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4
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Liu YX, Wan ZY, Wang R, Gutierrez-Farewik EM. A Method of Detecting Human Movement Intentions in Real Environments. IEEE Int Conf Rehabil Robot 2023; 2023:1-6. [PMID: 37941205 DOI: 10.1109/icorr58425.2023.10304774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2023]
Abstract
Accurate and timely movement intention detection can facilitate exoskeleton control during transitions between different locomotion modes. Detecting movement intentions in real environments remains a challenge due to unavoidable environmental uncertainties. False movement intention detection may also induce risks of falling and general danger for exoskeleton users. To this end, in this study, we developed a method for detecting human movement intentions in real environments. The proposed method is capable of online self-correcting by implementing a decision fusion layer. Gaze data from an eye tracker and inertial measurement unit (IMU) signals were fused at the feature extraction level and used to predict movement intentions using 2 different methods. Images from the scene camera embedded on the eye tracker were used to identify terrains using a convolutional neural network. The decision fusion was made based on the predicted movement intentions and identified terrains. Four able-bodied participants wearing the eye tracker and 7 IMU sensors took part in the experiments to complete the tasks of level ground walking, ramp ascending, ramp descending, stairs ascending, and stair descending. The recorded experimental data were used to test the feasibility of the proposed method. An overall accuracy of 93.4% was achieved when both feature fusion and decision fusion were used. Fusing gaze data with IMU signals improved the prediction accuracy.
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5
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Ebers MR, Rosenberg MC, Kutz JN, Steele KM. A machine learning approach to quantify individual gait responses to ankle exoskeletons. J Biomech 2023; 157:111695. [PMID: 37406604 DOI: 10.1016/j.jbiomech.2023.111695] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 06/14/2023] [Accepted: 06/19/2023] [Indexed: 07/07/2023]
Abstract
Predicting an individual's response to an exoskeleton and understanding what data are needed to characterize responses remains challenging. Specifically, we lack a theoretical framework capable of quantifying heterogeneous responses to exoskeleton interventions. We leverage a neural network-based discrepancy modeling framework to quantify complex changes in gait in response to passive ankle exoskeletons in nondisabled adults. Discrepancy modeling aims to resolve dynamical inconsistencies between model predictions and real-world measurements. Neural networks identified models of (i) Nominal gait, (ii) Exoskeleton (Exo) gait, and (iii) the Discrepancy (i.e., response) between them. If an Augmented (Nominal+Discrepancy) model captured exoskeleton responses, its predictions should account for comparable amounts of variance in Exo gait data as the Exo model. Discrepancy modeling successfully quantified individuals' exoskeleton responses without requiring knowledge about physiological structure or motor control: a model of Nominal gait augmented with a Discrepancy model of response accounted for significantly more variance in Exo gait (median R2 for kinematics (0.928-0.963) and electromyography (0.665-0.788), (p<0.042)) than the Nominal model (median R2 for kinematics (0.863-0.939) and electromyography (0.516-0.664)). However, additional measurement modalities and/or improved resolution are needed to characterize Exo gait, as the discrepancy may not comprehensively capture response due to unexplained variance in Exo gait (median R2 for kinematics (0.954-0.977) and electromyography (0.724-0.815)). These techniques can be used to accelerate the discovery of individual-specific mechanisms driving exoskeleton responses, thus enabling personalized rehabilitation.
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Affiliation(s)
- Megan R Ebers
- Department of Mechanical Engineering, University of Washington, Seattle, WA, 98195, USA.
| | - Michael C Rosenberg
- Department of Mechanical Engineering, University of Washington, Seattle, WA, 98195, USA; Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, GA, 30322, USA
| | - J Nathan Kutz
- Department of Applied Mathematics, University of Washington, Seattle, WA, 98195, USA
| | - Katherine M Steele
- Department of Mechanical Engineering, University of Washington, Seattle, WA, 98195, USA
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6
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Lora-Millan JS, Nabipour M, van Asseldonk E, Bayón C. Advances on mechanical designs for assistive ankle-foot orthoses. Front Bioeng Biotechnol 2023; 11:1188685. [PMID: 37485319 PMCID: PMC10361304 DOI: 10.3389/fbioe.2023.1188685] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Accepted: 06/27/2023] [Indexed: 07/25/2023] Open
Abstract
Assistive ankle-foot orthoses (AAFOs) are powerful solutions to assist or rehabilitate gait on humans. Existing AAFO technologies include passive, quasi-passive, and active principles to provide assistance to the users, and their mechanical configuration and control depend on the eventual support they aim for within the gait pattern. In this research we analyze the state-of-the-art of AAFO and classify the different approaches into clusters, describing their basis and working principles. Additionally, we reviewed the purpose and experimental validation of the devices, providing the reader with a better view of the technology readiness level. Finally, the reviewed designs, limitations, and future steps in the field are summarized and discussed.
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Affiliation(s)
| | - Mahdi Nabipour
- Department of Biomechanical Engineering, University of Twente, Enschede, Netherlands
| | - Edwin van Asseldonk
- Department of Biomechanical Engineering, University of Twente, Enschede, Netherlands
| | - Cristina Bayón
- Department of Biomechanical Engineering, University of Twente, Enschede, Netherlands
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7
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Park H, Kim S, Nussbaum MA, Srinivasan D. A pilot study investigating motor adaptations when learning to walk with a whole-body powered exoskeleton. J Electromyogr Kinesiol 2023; 69:102755. [PMID: 36921425 DOI: 10.1016/j.jelekin.2023.102755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 01/16/2023] [Accepted: 03/03/2023] [Indexed: 03/08/2023] Open
Abstract
Evidence is emerging on how whole-body powered exoskeleton (EXO) use impacts users in basic occupational work scenarios, yet our understanding of how users learn to use this complex technology is limited. We explored how novice users adapted to using an EXO during gait. Six novices and five experienced users completed the study. Novices completed an initial training/familiarization gait session, followed by three subsequent gait sessions using the EXO, while experienced users completed one gait session with the EXO. Spatiotemporal gait measures, pelvis and lower limb joint kinematics, muscle activities, EXO torques, and human-EXO interaction forces were measured. Adaptations among novices were most pronounced in spatiotemporal gait measures, followed by joint kinematics, with smaller changes evident in muscle activity and EXO joint torques. Compared to the experienced users, novices exhibited a shorter step length and walked with significantly greater anterior pelvic tilt and less hip extension. Novices also used lower joint torques from the EXO at the hip and knee, and they had greater biceps femoris activity. Overall, our results may suggest that novices exhibited clear progress in learning, but they had not yet adopted motor strategies similar to those of experienced users after the three sessions. We suggest potential future directions to enhance motor adaptations to powered EXO in terms of both training protocols and human-EXO interfaces.
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Affiliation(s)
- Hanjun Park
- Department of Industrial and Systems Engineering, Virginia Tech, Blacksburg, VA 24061, USA
| | - Sunwook Kim
- Department of Industrial and Systems Engineering, Virginia Tech, Blacksburg, VA 24061, USA
| | - Maury A Nussbaum
- Department of Industrial and Systems Engineering, Virginia Tech, Blacksburg, VA 24061, USA
| | - Divya Srinivasan
- Department of Industrial Engineering, Clemson University, Clemson, SC, USA.
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8
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Hashiguchi Y, Goto R, Naka T. Effects of orthoses on muscle activity and synergy during gait. PLoS One 2023; 18:e0281541. [PMID: 36757940 PMCID: PMC9910715 DOI: 10.1371/journal.pone.0281541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 01/25/2023] [Indexed: 02/10/2023] Open
Abstract
An orthosis is often used in rehabilitation to improve kinetic and kinematic parameters during gait. However, whether changes in neural control depend on wearing an orthosis during gait is unclear. We measured the muscle activity and synergy of the lower limb muscles without orthosis and with two types of orthoses: ankle-foot orthosis (AFO) and knee-ankle-foot orthosis (KAFO). Muscle activity during gait was measured in 15 healthy adults, and muscle synergies were extracted using non-negative matrix factorization. The results revealed that some muscle activities were significantly different among the three conditions. Post-hoc analysis indicated differences between each condition. Knee extensor muscle activity related to the loading response was significantly increased by wearing the AFO. In the KAFO condition, hip abductor muscle activity related to weight bearing was significantly decreased, and ankle dorsiflexor muscle activity was increased to secure clearance during the swing phase. However, the number of muscle synergies and complexity of muscle synergy did not significantly change among these conditions. However, along with changes in muscle activity, the activation pattern and weightings of muscle synergies tended to change with the use of orthoses. Each muscle activity was changed by wearing the orthosis; however, the immediate mechanical constraint did not change the framework of muscle synergy.
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Affiliation(s)
- Yu Hashiguchi
- Department of Physical Therapy, Faculty of Rehabilitation, Gunma PAZ University, Takasaki-shi, Gunma, Japan
- * E-mail:
| | - Ryosuke Goto
- Department of Speech-Language-Hearing Therapy, Faculty of Rehabilitation, Gunma PAZ University, Takasaki-shi, Gunma, Japan
| | - Toru Naka
- Department of Physical Therapy, Faculty of Rehabilitation, R Professional University of Rehabilitation, Tsuchiura-shi, Ibaraki, Japan
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9
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Zhou Y. Recent advances in wearable actuated ankle-foot orthoses: Medical effects, design, and control. Proc Inst Mech Eng H 2023; 237:163-178. [PMID: 36515408 DOI: 10.1177/09544119221142335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
This paper presents a survey on recent advances of wearable actuated ankle-foot orthoses (AAFOs). First of all, their medical functions are investigated. From the short-term aspect, they lead to rectification of pathological gaits, reduction of metabolic cost, and improvement of gait performance. After AAFO-based walking training with sufficient time, free walking performance can be enhanced. Then, key design factors are studied. First, primary design parameters are investigated. Second, common actuators are analysed. Third, human-robot interaction (HRI), ergonomics, safety, and application places, are considered. In the following section, control technologies are reviewed from the aspects of rehabilitation stages, gait feature quantities, and controller characteristics. Finally, existing problems are discussed; development trends are prospected.
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Affiliation(s)
- Yuan Zhou
- Department of Biomedical Engineering, City University of Hong Kong, Hong Kong, China
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10
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Jeong H, Haghighat P, Kantharaju P, Jacobson M, Jeong H, Kim M. Muscle coordination and recruitment during squat assistance using a robotic ankle-foot exoskeleton. Sci Rep 2023; 13:1363. [PMID: 36693935 PMCID: PMC9873637 DOI: 10.1038/s41598-023-28229-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Accepted: 01/16/2023] [Indexed: 01/26/2023] Open
Abstract
Squatting is an intensive activity routinely performed in the workplace to lift and lower loads. The effort to perform a squat can decrease using an exoskeleton that considers individual worker's differences and assists them with a customized solution, namely, personalized assistance. Designing such an exoskeleton could be improved by understanding how the user's muscle activity changes when assistance is provided. This study investigated the change in the muscle recruitment and activation pattern when personalized assistance was provided. The personalized assistance was provided by an ankle-foot exoskeleton during squatting and we compared its effect with that of the no-device and unpowered exoskeleton conditions using previously collected data. We identified four main muscle recruitment strategies across ten participants. One of the strategies mainly used quadriceps muscles, and the activation level corresponding to the strategy was reduced under exoskeleton assistance compared to the no-device and unpowered conditions. These quadriceps dominant synergy and rectus femoris activations showed reasonable correlations (r = 0.65, 0.59) to the metabolic cost of squatting. These results indicate that the assistance helped reduce quadriceps activation, and thus, the metabolic cost of squatting. These outcomes suggest that the muscle recruitment and activation patterns could be used to design an exoskeleton and training methods.
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Affiliation(s)
- Hyeongkeun Jeong
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL, 60607, USA
| | - Parian Haghighat
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL, 60607, USA
| | - Prakyath Kantharaju
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL, 60607, USA
| | - Michael Jacobson
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL, 60607, USA
| | - Heejin Jeong
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL, 60607, USA.,Ira A. Fulton Schools of Engineering, Arizona State University, Arizona, Mesa, AZ, 85212, USA
| | - Myunghee Kim
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL, 60607, USA.
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11
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Ebers MR, Rosenberg MC, Kutz JN, Steele KM. A machine learning approach to quantify individual gait responses to ankle exoskeletons. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.20.524757. [PMID: 36711530 PMCID: PMC9882260 DOI: 10.1101/2023.01.20.524757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
We currently lack a theoretical framework capable of characterizing heterogeneous responses to exoskeleton interventions. Predicting an individual's response to an exoskeleton and understanding what data are needed to characterize responses has been a persistent challenge. In this study, we leverage a neural network-based discrepancy modeling framework to quantify complex changes in gait in response to passive ankle exoskeletons in nondisabled adults. Discrepancy modeling aims to resolve dynamical inconsistencies between model predictions and real-world measurements. Neural networks identified models of (i) Nominal gait, (ii) Exoskeleton ( Exo ) gait, and (iii) the Discrepancy ( i.e. , response) between them. If an Augmented (Nominal+Discrepancy) model captured exoskeleton responses, its predictions should account for comparable amounts of variance in Exo gait data as the Exo model. Discrepancy modeling successfully quantified individuals' exoskeleton responses without requiring knowledge about physiological structure or motor control: a model of Nominal gait augmented with a Discrepancy model of response accounted for significantly more variance in Exo gait (median R 2 for kinematics (0.928 - 0.963) and electromyography (0.665 - 0.788), ( p < 0.042)) than the Nominal model (median R 2 for kinematics (0.863 - 0.939) and electromyography (0.516 - 0.664)). However, additional measurement modalities and/or improved resolution are needed to characterize Exo gait, as the discrepancy may not comprehensively capture response due to unexplained variance in Exo gait (median R 2 for kinematics (0.954 - 0.977) and electromyography (0.724 - 0.815)). These techniques can be used to accelerate the discovery of individual-specific mechanisms driving exoskeleton responses, thus enabling personalized rehabilitation.
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Affiliation(s)
- Megan R Ebers
- Department of Mechanical Engineering, University of Washington, Seattle, WA, 98195, USA
| | - Michael C Rosenberg
- Department of Mechanical Engineering, University of Washington, Seattle, WA, 98195, USA
- Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, GA, 30322, USA
| | - J Nathan Kutz
- Department of Applied Mathematics, University of Washington, Seattle, WA, 98195, USA
| | - Katherine M Steele
- Department of Mechanical Engineering, University of Washington, Seattle, WA, 98195, USA
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12
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Schmitz DG, Nuckols RW, Lee S, Akbas T, Swaminathan K, Walsh CJ, Thelen DG. Modulation of Achilles tendon force with load carriage and exosuit assistance. Sci Robot 2022; 7:eabq1514. [DOI: 10.1126/scirobotics.abq1514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Exosuits have the potential to assist locomotion in both healthy and pathological populations, but the effect of exosuit assistance on the underlying muscle-tendon tissue loading is not yet understood. In this study, we used shear wave tensiometers to characterize the modulation of Achilles tendon force with load carriage and exosuit assistance at the ankle. When walking (1.25 m/s) unassisted on a treadmill with load carriage weights of 15 and 30% of body weight, peak Achilles tendon force increased by 11 and 23%, respectively. Ankle exosuit assistance significantly reduced peak Achilles tendon force relative to unassisted, although the magnitude of change was variable across participants. Peak Achilles tendon force was significantly correlated with peak ankle torque for unassisted walking across load carriage conditions. However, when ankle plantarflexor assistance was applied, the relationship between peak tendon force and peak biological ankle torque was no longer significant. An outdoor pilot study was conducted in which a wearable shear wave tensiometer was used to measure Achilles tendon wave speed and compare across an array of assistance loading profiles. Reductions in tendon loading varied depending on the profile, highlighting the importance of in vivo measurements of muscle and tendon forces when studying and optimizing exoskeletons and exosuits.
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Affiliation(s)
- Dylan G. Schmitz
- Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI, USA
| | - Richard W. Nuckols
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Sangjun Lee
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Tunc Akbas
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Krithika Swaminathan
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Conor J. Walsh
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Darryl G. Thelen
- Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI, USA
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13
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Zhvansky DS, Sylos-Labini F, Dewolf A, Cappellini G, d’Avella A, Lacquaniti F, Ivanenko Y. Evaluation of Spatiotemporal Patterns of the Spinal Muscle Coordination Output during Walking in the Exoskeleton. SENSORS (BASEL, SWITZERLAND) 2022; 22:s22155708. [PMID: 35957264 PMCID: PMC9370895 DOI: 10.3390/s22155708] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2022] [Revised: 07/21/2022] [Accepted: 07/26/2022] [Indexed: 06/01/2023]
Abstract
Recent advances in the performance and evaluation of walking in exoskeletons use various assessments based on kinematic/kinetic measurements. While such variables provide general characteristics of gait performance, only limited conclusions can be made about the neural control strategies. Moreover, some kinematic or kinetic parameters are a consequence of the control implemented on the exoskeleton. Therefore, standard indicators based on kinematic variables have limitations and need to be complemented by performance measures of muscle coordination and control strategy. Knowledge about what happens at the spinal cord output level might also be critical for rehabilitation since an abnormal spatiotemporal integration of activity in specific spinal segments may result in a risk for abnormalities in gait recovery. Here we present the PEPATO software, which is a benchmarking solution to assess changes in the spinal locomotor output during walking in the exoskeleton with respect to reference data on normal walking. In particular, functional and structural changes at the spinal cord level can be mapped into muscle synergies and spinal maps of motoneuron activity. A user-friendly software interface guides the user through several data processing steps leading to a set of performance indicators as output. We present an example of the usage of this software for evaluating walking in an unloading exoskeleton that allows a person to step in simulated reduced (the Moon's) gravity. By analyzing the EMG activity from lower limb muscles, the algorithms detected several performance indicators demonstrating differential adaptation (shifts in the center of activity, prolonged activation) of specific muscle activation modules and spinal motor pools and increased coactivation of lumbar and sacral segments. The software is integrated at EUROBENCH facilities to benchmark the performance of walking in the exoskeleton from the point of view of changes in the spinal locomotor output.
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Affiliation(s)
- Dmitry S. Zhvansky
- Institute for Information Transmission Problems, Russian Academy of Sciences, 127994 Moscow, Russia;
| | - Francesca Sylos-Labini
- Laboratory of Neuromotor Physiology, IRCCS Santa Lucia Foundation, 00179 Rome, Italy; (F.S.-L.); (A.D.); (G.C.); (A.d.); (F.L.)
- Department of Systems Medicine, University of Rome Tor Vergata, 00133 Rome, Italy
| | - Arthur Dewolf
- Laboratory of Neuromotor Physiology, IRCCS Santa Lucia Foundation, 00179 Rome, Italy; (F.S.-L.); (A.D.); (G.C.); (A.d.); (F.L.)
- Department of Systems Medicine, University of Rome Tor Vergata, 00133 Rome, Italy
| | - Germana Cappellini
- Laboratory of Neuromotor Physiology, IRCCS Santa Lucia Foundation, 00179 Rome, Italy; (F.S.-L.); (A.D.); (G.C.); (A.d.); (F.L.)
- Department of Systems Medicine, University of Rome Tor Vergata, 00133 Rome, Italy
| | - Andrea d’Avella
- Laboratory of Neuromotor Physiology, IRCCS Santa Lucia Foundation, 00179 Rome, Italy; (F.S.-L.); (A.D.); (G.C.); (A.d.); (F.L.)
- Department of Biomedical and Dental Sciences and Morphofunctional Imaging, University of Messina, 98100 Messina, Italy
| | - Francesco Lacquaniti
- Laboratory of Neuromotor Physiology, IRCCS Santa Lucia Foundation, 00179 Rome, Italy; (F.S.-L.); (A.D.); (G.C.); (A.d.); (F.L.)
- Department of Systems Medicine and Center of Space Biomedicine, University of Rome Tor Vergata, 00133 Rome, Italy
| | - Yury Ivanenko
- Laboratory of Neuromotor Physiology, IRCCS Santa Lucia Foundation, 00179 Rome, Italy; (F.S.-L.); (A.D.); (G.C.); (A.d.); (F.L.)
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14
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Foot contact forces can be used to personalize a wearable robot during human walking. Sci Rep 2022; 12:10947. [PMID: 35768457 PMCID: PMC9243054 DOI: 10.1038/s41598-022-14776-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Accepted: 06/13/2022] [Indexed: 11/09/2022] Open
Abstract
Individuals with below-knee amputation (BKA) experience increased physical effort when walking, and the use of a robotic ankle-foot prosthesis (AFP) can reduce such effort. The walking effort could be further reduced if the robot is personalized to the wearer using human-in-the-loop (HIL) optimization of wearable robot parameters. The conventional physiological measurement, however, requires a long estimation time, hampering real-time optimization due to the limited experimental time budget. This study hypothesized that a function of foot contact force, the symmetric foot force-time integral (FFTI), could be used as a cost function for HIL optimization to rapidly estimate the physical effort of walking. We found that the new cost function presents a reasonable correlation with measured metabolic cost. When we employed the new cost function in HIL ankle-foot prosthesis stiffness parameter optimization, 8 individuals with simulated amputation reduced their metabolic cost of walking, greater than 15% (p < 0.02), compared to the weight-based and control-off conditions. The symmetry cost using the FFTI percentage was lower for the optimal condition, compared to all other conditions (p < 0.05). This study suggests that foot force-time integral symmetry using foot pressure sensors can be used as a cost function when optimizing a wearable robot parameter.
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15
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Lora-Millan JS, Moreno JC, Rocon E. Coordination Between Partial Robotic Exoskeletons and Human Gait: A Comprehensive Review on Control Strategies. Front Bioeng Biotechnol 2022; 10:842294. [PMID: 35694226 PMCID: PMC9174608 DOI: 10.3389/fbioe.2022.842294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 04/28/2022] [Indexed: 12/02/2022] Open
Abstract
Lower-limb robotic exoskeletons have become powerful tools to assist or rehabilitate the gait of subjects with impaired walking, even when they are designed to act only partially over the locomotor system, as in the case of unilateral or single-joint exoskeletons. These partial exoskeletons require a proper method to synchronize their assistive actions and ensure correct inter-joint coordination with the user’s gait. This review analyzes the state of the art of control strategies to coordinate the assistance provided by these partial devices with the actual gait of the wearers. We have analyzed and classified the different approaches independently of the hardware implementation, describing their basis and principles. We have also reviewed the experimental validations of these devices for impaired and unimpaired walking subjects to provide the reader with a clear view of their technology readiness level. Eventually, the current state of the art and necessary future steps in the field are summarized and discussed.
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Affiliation(s)
- Julio S. Lora-Millan
- Centre for Automation and Robotics, Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Madrid, CSIC-UPM, Madrid, Spain
- Electronic Technology Department, Universidad Rey Juan Carlos, Madrid, Spain
| | - Juan C. Moreno
- Neural Rehabilitation Group, Cajal Institute, Spanish National Research Council (CSIC), Madrid, Spain
| | - E. Rocon
- Centre for Automation and Robotics, Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Madrid, CSIC-UPM, Madrid, Spain
- *Correspondence: E. Rocon,
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16
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Abram SJ, Poggensee KL, Sánchez N, Simha SN, Finley JM, Collins SH, Donelan JM. General variability leads to specific adaptation toward optimal movement policies. Curr Biol 2022; 32:2222-2232.e5. [PMID: 35537453 PMCID: PMC9504978 DOI: 10.1016/j.cub.2022.04.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2021] [Revised: 02/03/2022] [Accepted: 04/07/2022] [Indexed: 01/29/2023]
Abstract
Our nervous systems can learn optimal control policies in response to changes to our bodies, tasks, and movement contexts. For example, humans can learn to adapt their control policy in walking contexts where the energy-optimal policy is shifted along variables such as step frequency or step width. However, it is unclear how the nervous system determines which ways to adapt its control policy. Here, we asked how human participants explore through variations in their control policy to identify more optimal policies in new contexts. We created new contexts using exoskeletons that apply assistive torques to each ankle at each walking step. We analyzed four variables that spanned the levels of the whole movement, the joint, and the muscle: step frequency, ankle angle range, total soleus activity, and total medial gastrocnemius activity. We found that, across all of these analyzed variables, variability increased upon initial exposure to new contexts and then decreased with experience. This led to adaptive changes in the magnitude of specific variables, and these changes were correlated with reduced energetic cost. The timescales by which adaptive changes progressed and variability decreased were faster for some variables than others, suggesting a reduced search space within which the nervous system continues to optimize its policy. These collective findings support the principle that exploration through general variability leads to specific adaptation toward optimal movement policies.
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Affiliation(s)
- Sabrina J. Abram
- School of Engineering Science, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
| | | | - Natalia Sánchez
- Division of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, CA 90089, USA
| | - Surabhi N. Simha
- Department of Biomedical Engineering, Emory University, Atlanta, GA 30322, USA
| | - James M. Finley
- Division of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, CA 90089, USA,Department of Biomedical Engineering, University of Southern California, Los Angeles, CA 90089, USA,Neuroscience Graduate Program, University of Southern California, Los Angeles, CA 90089, USA
| | - Steven H. Collins
- Department of Mechanical Engineering, Stanford University, Stanford, CA 94305, USA
| | - J. Maxwell Donelan
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC V5A 1S6, Canada,Twitter: @maxdonelan,Lead contact,Correspondence:
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17
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Application of Wearable Sensors in Actuation and Control of Powered Ankle Exoskeletons: A Comprehensive Review. SENSORS 2022; 22:s22062244. [PMID: 35336413 PMCID: PMC8954890 DOI: 10.3390/s22062244] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 02/28/2022] [Accepted: 03/08/2022] [Indexed: 02/06/2023]
Abstract
Powered ankle exoskeletons (PAEs) are robotic devices developed for gait assistance, rehabilitation, and augmentation. To fulfil their purposes, PAEs vastly rely heavily on their sensor systems. Human–machine interface sensors collect the biomechanical signals from the human user to inform the higher level of the control hierarchy about the user’s locomotion intention and requirement, whereas machine–machine interface sensors monitor the output of the actuation unit to ensure precise tracking of the high-level control commands via the low-level control scheme. The current article aims to provide a comprehensive review of how wearable sensor technology has contributed to the actuation and control of the PAEs developed over the past two decades. The control schemes and actuation principles employed in the reviewed PAEs, as well as their interaction with the integrated sensor systems, are investigated in this review. Further, the role of wearable sensors in overcoming the main challenges in developing fully autonomous portable PAEs is discussed. Finally, a brief discussion on how the recent technology advancements in wearable sensors, including environment—machine interface sensors, could promote the future generation of fully autonomous portable PAEs is provided.
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18
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Acosta-Sojo Y, Stirling L. Individuals differ in muscle activation patterns during early adaptation to a powered ankle exoskeleton. APPLIED ERGONOMICS 2022; 98:103593. [PMID: 34600306 DOI: 10.1016/j.apergo.2021.103593] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 08/03/2021] [Accepted: 09/20/2021] [Indexed: 06/13/2023]
Abstract
Exoskeletons have the potential to assist users and augment physical ability. To achieve these goals across users, individual variation in muscle activation patterns when using an exoskeleton need to be evaluated. This study examined individual muscle activation patterns during walking with a powered ankle exoskeleton. 60% of the participants were observed to reduce medial gastrocnemius activation with exoskeleton powered and increase with the exoskeleton unpowered during stance. 80% of the participants showed a significant increase in tibialis anterior activation upon power addition, with inconsistent changes upon power removal during swing. 60% of the participants that were able to adapt to the system, did not de-adapt after 5 min. Muscle activity patterns differ between individuals in response to the exoskeleton power state, and affected the antagonist muscle behavior during this early adaptation. It is important to understand these different individual behaviors to inform the design of exoskeleton controllers and training protocols.
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Affiliation(s)
- Yadrianna Acosta-Sojo
- Industrial and Operations Engineering, University of Michigan, Ann Arbor, MI, 48109, USA.
| | - Leia Stirling
- Industrial and Operations Engineering, University of Michigan, Ann Arbor, MI, 48109, USA; Robotics Institute, University of Michigan, Ann Arbor, MI, 48109, USA
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19
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Wei B, Ding Z, Yi C, Guo H, Wang Z, Zhu J, Jiang F. A Novel sEMG-Based Gait Phase-Kinematics-Coupled Predictor and Its Interaction With Exoskeletons. Front Neurorobot 2021; 15:704226. [PMID: 34447302 PMCID: PMC8384035 DOI: 10.3389/fnbot.2021.704226] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2021] [Accepted: 07/15/2021] [Indexed: 11/13/2022] Open
Abstract
The interaction between human and exoskeletons increasingly relies on the precise decoding of human motion. One main issue of the current motion decoding algorithms is that seldom algorithms provide both discrete motion patterns (e.g., gait phases) and continuous motion parameters (e.g., kinematics). In this paper, we propose a novel algorithm that uses the surface electromyography (sEMG) signals that are generated prior to their corresponding motions to perform both gait phase recognition and lower-limb kinematics prediction. Particularly, we first propose an end-to-end architecture that uses the gait phase and EMG signals as the priori of the kinematics predictor. In so doing, the prediction of kinematics can be enhanced by the ahead-of-motion property of sEMG and quasi-periodicity of gait phases. Second, we propose to select the optimal muscle set and reduce the number of sensors according to the muscle effects in a gait cycle. Finally, we experimentally investigate how the assistance of exoskeletons can affect the motion intent predictor, and we propose a novel paradigm to make the predictor adapt to the change of data distribution caused by the exoskeleton assistance. The experiments on 10 subjects demonstrate the effectiveness of our algorithm and reveal the interaction between assistance and the kinematics predictor. This study would aid the design of exoskeleton-oriented motion-decoding and human–machine interaction methods.
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Affiliation(s)
- Baichun Wei
- School of Computer Science and Technology, Harbin Institute of Technology, Harbin, China.,Pengcheng Laboratory, Shenzhen, China
| | - Zhen Ding
- School of Mechatronics Engineering, Harbin Institute of Technology, Harbin, China
| | - Chunzhi Yi
- School of Mechatronics Engineering, Harbin Institute of Technology, Harbin, China
| | - Hao Guo
- School of Computer Science and Technology, Harbin Institute of Technology, Harbin, China.,Pengcheng Laboratory, Shenzhen, China
| | - Zhipeng Wang
- School of Mechatronics Engineering, Harbin Institute of Technology, Harbin, China
| | - Jianfei Zhu
- School of Mechatronics Engineering, Harbin Institute of Technology, Harbin, China
| | - Feng Jiang
- School of Computer Science and Technology, Harbin Institute of Technology, Harbin, China.,Pengcheng Laboratory, Shenzhen, China
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20
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Collimore AN, Aiello AJ, Pohlig RT, Awad LN. The Dynamic Motor Control Index as a Marker of Age-Related Neuromuscular Impairment. Front Aging Neurosci 2021; 13:678525. [PMID: 34366824 PMCID: PMC8339561 DOI: 10.3389/fnagi.2021.678525] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 06/11/2021] [Indexed: 12/22/2022] Open
Abstract
Biomarkers that can identify age-related decline in walking function have potential to promote healthier aging by triggering timely interventions that can mitigate or reverse impairments. Recent evidence suggests that changes in neuromuscular control precede changes in walking function; however, it is unclear which measures are best suited for identifying age-related changes. In this study, non-negative matrix factorization of electromyography data collected during treadmill walking was used to calculate two measures of the complexity of muscle co-activations during walking for 36 adults: (1) the number of muscle synergies and (2) the dynamic motor control index. Study participants were grouped into young (18–35 years old), young-old (65–74 years old), and old–old (75+ years old) subsets. We found that the dynamic motor control index [χ2(2) = 9.41, p = 0.009], and not the number of muscle synergies [χ2(2) = 5.42, p = 0.067], differentiates between age groups [χ2(4) = 10.62, p = 0.031, Nagelkerke R2 = 0.297]. Moreover, an impairment threshold set at a dynamic motor control index of 90 (i.e., one standard deviation below the young adults) was able to differentiate between age groups [χ2(2) = 9.351, p = 0.009]. The dynamic motor control index identifies age-related differences in neuromuscular complexity not measured by the number of muscle synergies and may have clinical utility as a marker of neuromotor impairment.
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Affiliation(s)
- Ashley N Collimore
- Neuromotor Recovery Laboratory, Department of Physical Therapy, College of Health and Rehabilitation Sciences: Sargent College, Boston University, Boston, MA, United States
| | - Ashlyn J Aiello
- Neuromotor Recovery Laboratory, Department of Physical Therapy, College of Health and Rehabilitation Sciences: Sargent College, Boston University, Boston, MA, United States
| | - Ryan T Pohlig
- Biostatistics Core Facility, University of Delaware, Newark, DE, United States
| | - Louis N Awad
- Neuromotor Recovery Laboratory, Department of Physical Therapy, College of Health and Rehabilitation Sciences: Sargent College, Boston University, Boston, MA, United States
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21
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Effects of body weight support and guidance force settings on muscle synergy during Lokomat walking. Eur J Appl Physiol 2021; 121:2967-2980. [PMID: 34218291 DOI: 10.1007/s00421-021-04762-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 06/29/2021] [Indexed: 01/05/2023]
Abstract
BACKGROUND The Lokomat is a robotic device that has been suggested to make gait therapy easier, more comfortable, and more efficient. In this study, we asked whether the Lokomat promotes physiological muscle activation patterns, a fundamental question when considering motor learning and adaptation. METHODS We investigated lower limb muscles coordination in terms of muscle activity level, muscle activity pattern similarity, and muscle synergy in 15 healthy participants walking at 3 km/h on either a treadmill or in a Lokomat at various guidance forces (GF: 30, 50 or 70%) and body weight supports (BWS: 30, 50 or 70% of participant's body weight). RESULTS Walking in the Lokomat was associated with a greater activation level of the rectus femoris and vastus medialis (×2-3) compared to treadmill walking. The level of activity tended to be diminished in gastrocnemius and semi-tendinosus, which particularly affected the similarity with treadmill walking (normalized scalar product NSP = 0.7-0.8). GF and BWS independently altered the muscle activation pattern in terms of amplitude and shape. Increasing BWS decreased the level of activity in all but one muscle (the soleus). Increasing GF slightly improved the similarity with treadmill walking for the tibialis anterior and vastus medialis muscles. The muscle synergies (N = 4) were similar (NSP = 0.93-0.97), but a cross-validation procedure revealed an alteration by the Lokomat. The activation of these synergies differed (NSP = 0.74-0.82). CONCLUSION The effects of GF and BWS are modest compared to the effect of the Lokomat itself, suggesting that Lokomat design should be improved to promote more typical muscle activity patterns.
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22
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Liu YX, Wang R, Gutierrez-Farewik EM. A Muscle Synergy-Inspired Method of Detecting Human Movement Intentions Based on Wearable Sensor Fusion. IEEE Trans Neural Syst Rehabil Eng 2021; 29:1089-1098. [PMID: 34097615 DOI: 10.1109/tnsre.2021.3087135] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Detecting human movement intentions is fundamental to neural control of robotic exoskeletons, as it is essential for achieving seamless transitions between different locomotion modes. In this study, we enhanced a muscle synergy-inspired method of locomotion mode identification by fusing the electromyography data with two types of data from wearable sensors (inertial measurement units), namely linear acceleration and angular velocity. From the finite state machine perspective, the enhanced method was used to systematically identify 2 static modes, 7 dynamic modes, and 27 transitions among them. In addition to the five broadly studied modes (level ground walking, ramps ascent/descent, stairs ascent/descent), we identified the transition between different walking speeds and modes of ramp walking at different inclination angles. Seven combinations of sensor fusion were conducted, on experimental data from 8 able-bodied adult subjects, and their classification accuracy and prediction time were compared. Prediction based on a fusion of electromyography and gyroscope (angular velocity) data predicted transitions earlier and with higher accuracy. All transitions and modes were identified with a total average classification accuracy of 94.5% with fused sensor data. For nearly all transitions, we were able to predict the next locomotion mode 300-500ms prior to the step into that mode.
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23
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Zhu F, Kern M, Fowkes E, Afzal T, Contreras-Vidal JL, Francisco GE, Chang SH. Effects of an exoskeleton-assisted gait training on post-stroke lower-limb muscle coordination. J Neural Eng 2021; 18. [PMID: 33752175 DOI: 10.1088/1741-2552/abf0d5] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Accepted: 03/22/2021] [Indexed: 11/11/2022]
Abstract
Objective.Powered exoskeletons have been used to help persons with gait impairment regain some walking ability. However, little is known about its impact on neuromuscular coordination in persons with stroke. The objective of this study is to investigate how a powered exoskeleton could affect the neuromuscular coordination of persons with post-stroke hemiparesis.Approach.Eleven able-bodied subjects and ten stroke subjects participated in a single-visit treadmill walking assessment, in which their motion and lower-limb muscle activities were captured. By comparing spatiotemporal parameters, kinematics, and muscle synergy pattern between two groups, we characterized the normal gait pattern and the post-stroke motor deficits. Five eligible stroke subjects received exoskeleton-assisted gait trainings and walking assessments were conducted pre-intervention (Pre) and post-intervention (Post), without (WO) and with (WT) the exoskeleton. We compared their gait performance between (a) Pre and Post to investigate the effect of exoskeleton-assisted gait training and, (b) WO and WT the exoskeleton to investigate the effect of exoskeleton wearing on stroke subjects.Main results.While four distinct motor modules were needed to describe lower-extremity activities during stead-speed walking among able-bodied subjects, three modules were sufficient for the paretic leg from the stroke subjects. Muscle coordination complexity, module composition and activation timing were preserved after the training, indicating the intervention did not significantly change the neuromuscular coordination. In contrast, walking WT the exoskeleton altered the stroke subjects' synergy pattern, especially on the paretic side. The changes were dominated by the activation profile modulation towards the normal pattern observed from the able-bodied group.Significance.This study gave us some critical insight into how a powered exoskeleton affects the stroke subjects' neuromuscular coordination during gait and demonstrated the potential to use muscle synergy as a method to evaluate the effect of the exoskeleton training.This study was registered at ClinicalTrials.gov (identifier: NCT03057652).
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Affiliation(s)
- Fangshi Zhu
- Department of Physical Medicine and Rehabilitation, The University of Texas Health Science Center at Houston, Houston, TX, United States of America.,Center for Wearable Exoskeletons, NeuroRecovery Research Center, TIRR Memorial Hermann, Houston, TX, United States of America
| | - Marcie Kern
- Center for Wearable Exoskeletons, NeuroRecovery Research Center, TIRR Memorial Hermann, Houston, TX, United States of America
| | - Erin Fowkes
- Center for Wearable Exoskeletons, NeuroRecovery Research Center, TIRR Memorial Hermann, Houston, TX, United States of America
| | - Taimoor Afzal
- Department of Physical Medicine and Rehabilitation, The University of Texas Health Science Center at Houston, Houston, TX, United States of America.,Center for Wearable Exoskeletons, NeuroRecovery Research Center, TIRR Memorial Hermann, Houston, TX, United States of America
| | - Jose-Luis Contreras-Vidal
- Department of Electrical and Computer Engineering, The University of Houston, Houston, TX, United States of America
| | - Gerard E Francisco
- Department of Physical Medicine and Rehabilitation, The University of Texas Health Science Center at Houston, Houston, TX, United States of America.,Center for Wearable Exoskeletons, NeuroRecovery Research Center, TIRR Memorial Hermann, Houston, TX, United States of America
| | - Shuo-Hsiu Chang
- Department of Physical Medicine and Rehabilitation, The University of Texas Health Science Center at Houston, Houston, TX, United States of America.,Center for Wearable Exoskeletons, NeuroRecovery Research Center, TIRR Memorial Hermann, Houston, TX, United States of America
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24
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Ding Z, Yang C, Wang Z, Yin X, Jiang F. Online Adaptive Prediction of Human Motion Intention Based on sEMG. SENSORS 2021; 21:s21082882. [PMID: 33924152 PMCID: PMC8074390 DOI: 10.3390/s21082882] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Revised: 04/16/2021] [Accepted: 04/18/2021] [Indexed: 11/20/2022]
Abstract
Accurate and reliable motion intention perception and prediction are keys to the exoskeleton control system. In this paper, a motion intention prediction algorithm based on sEMG signal is proposed to predict joint angle and heel strike time in advance. To ensure the accuracy and reliability of the prediction algorithm, the proposed method designs the sEMG feature extraction network and the online adaptation network. The feature extraction utilizes the convolution autoencoder network combined with muscle synergy characteristics to get the high-compression sEMG feature to aid motion prediction. The adaptation network ensures the proposed prediction method can still maintain a certain prediction accuracy even the sEMG signals distribution changes by adjusting some parameters of the feature extraction network and the prediction network online. Ten subjects were recruited to collect surface EMG data from nine muscles on the treadmill. The proposed prediction algorithm can predict the knee angle 101.25 ms in advance with 2.36 degrees accuracy. The proposed prediction algorithm also can predict the occurrence time of initial contact 236±9 ms in advance. Meanwhile, the proposed feature extraction method can achieve 90.71±3.42% accuracy of sEMG reconstruction and can guarantee 73.70±5.01% accuracy even when the distribution of sEMG is changed without any adjustment. The online adaptation network enhances the accuracy of sEMG reconstruction of CAE to 87.65±3.83% and decreases the angle prediction error from 4.03∘ to 2.36∘. The proposed method achieves effective motion prediction in advance and alleviates the influence caused by the non-stationary of sEMG.
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Affiliation(s)
- Zhen Ding
- School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150000, China; (Z.D.); (C.Y.); (Z.W.); (X.Y.)
| | - Chifu Yang
- School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150000, China; (Z.D.); (C.Y.); (Z.W.); (X.Y.)
| | - Zhipeng Wang
- School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150000, China; (Z.D.); (C.Y.); (Z.W.); (X.Y.)
| | - Xunfeng Yin
- School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150000, China; (Z.D.); (C.Y.); (Z.W.); (X.Y.)
| | - Feng Jiang
- School of Computer Science and Technology, Harbin Institute of Technology, Harbin 150000, China
- Correspondence:
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25
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Hussain S, Jamwal PK, Vliet PV, Brown NAT. Robot Assisted Ankle Neuro-Rehabilitation: State of the art and Future Challenges. Expert Rev Neurother 2020; 21:111-121. [PMID: 33198522 DOI: 10.1080/14737175.2021.1847646] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Introduction: Robot-assisted neuro-rehabilitation is gaining acceptability among the physical therapy community. The ankle is one of the most complicated anatomical joints in the human body and neurologic injuries such as stroke often result in ankle and foot disabilities. Areas covered: Robotic solutions for the ankle joint physical therapy have extensively been researched. Significant research has been conducted on the mechanism design, actuation as well as control of these ankle rehabilitation robots. Also, the experimental evaluations of these robots have been conducted with healthy and neurologically impaired subjects. This paper presents a comprehensive review of the recent developments in the field of robot-assisted ankle rehabilitation. Mechanism design, actuation, and various types of control strategies are discussed. Also, the experimental evaluations of these ankle rehabilitation robots are discussed in the context of the evaluation of robotic hardware with healthy subjects as well as motor function outcomes with neurologically impaired subjects. Expert opinion: Significant progress in the mechanism design, control, and experimental evaluations of the ankle rehabilitation robots have been reported. However, more sensing and reference trajectory generation methods need to be developed as well as more objective quantitive evaluations that need to be conducted for establishing the clinical significance of these robots.
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Affiliation(s)
- Shahid Hussain
- Human-Centred Technology Research Center, Faculty of Science and Technology, University of Canberra , Canberra, ACT, Australia
| | - Prashant K Jamwal
- Department of Electrical and Computer Engineering, Nazarbayev University , Astana, Kazakhstan
| | - Paulette V Vliet
- Research and Innovation Division, University of Newcastle , Callaghan, NSW, Australia
| | - Nicholas A T Brown
- The Faculty of Health and University of Canberra Hospital, University of Canberra , Canberra, ACT, Australia
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26
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Rosenberg MC, Banjanin BS, Burden SA, Steele KM. Predicting walking response to ankle exoskeletons using data-driven models. J R Soc Interface 2020; 17:20200487. [PMID: 33050782 DOI: 10.1098/rsif.2020.0487] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Despite recent innovations in exoskeleton design and control, predicting subject-specific impacts of exoskeletons on gait remains challenging. We evaluated the ability of three classes of subject-specific phase-varying (PV) models to predict kinematic and myoelectric responses to ankle exoskeletons during walking, without requiring prior knowledge of specific user characteristics. Each model-PV, linear PV (LPV) and nonlinear PV (NPV)-leveraged Floquet theory to predict deviations from a nominal gait cycle due to exoskeleton torque, though the models differed in complexity and expected prediction accuracy. For 12 unimpaired adults walking with bilateral passive ankle exoskeletons, we predicted kinematics and muscle activity in response to three exoskeleton torque conditions. The LPV model's predictions were more accurate than the PV model when predicting less than 12.5% of a stride in the future and explained 49-70% of the variance in hip, knee and ankle kinematic responses to torque. The LPV model also predicted kinematic responses with similar accuracy to the more-complex NPV model. Myoelectric responses were challenging to predict with all models, explaining at most 10% of the variance in responses. This work highlights the potential of data-driven PV models to predict complex subject-specific responses to ankle exoskeletons and inform device design and control.
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Affiliation(s)
- Michael C Rosenberg
- Department of Mechanical Engineering, University of Washington, Seattle, WA, USA
| | - Bora S Banjanin
- Department of Electrical and Computer Engineering, University of Washington, Seattle, WA, USA
| | - Samuel A Burden
- Department of Electrical and Computer Engineering, University of Washington, Seattle, WA, USA
| | - Katherine M Steele
- Department of Mechanical Engineering, University of Washington, Seattle, WA, USA
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Rinaldi L, Yeung LF, Lam PCH, Pang MYC, Tong RKY, Cheung VCK. Adapting to the Mechanical Properties and Active Force of an Exoskeleton by Altering Muscle Synergies in Chronic Stroke Survivors. IEEE Trans Neural Syst Rehabil Eng 2020; 28:2203-2213. [DOI: 10.1109/tnsre.2020.3017128] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Bekius A, Bach MM, van der Krogt MM, de Vries R, Buizer AI, Dominici N. Muscle Synergies During Walking in Children With Cerebral Palsy: A Systematic Review. Front Physiol 2020; 11:632. [PMID: 32714199 PMCID: PMC7343959 DOI: 10.3389/fphys.2020.00632] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Accepted: 05/18/2020] [Indexed: 12/27/2022] Open
Abstract
Background: Walking problems in children with cerebral palsy (CP) can in part be explained by limited selective motor control. Muscle synergy analysis is increasingly used to quantify altered neuromuscular control during walking. The early brain injury in children with CP may lead to a different development of muscle synergies compared to typically developing (TD) children, which might characterize the abnormal walking patterns. Objective: The overarching aim of this review is to give an overview of the existing studies investigating muscle synergies during walking in children with CP compared to TD children. The main focus is on how muscle synergies differ between children with CP and TD children, and we examine the potential of muscle synergies as a measure to quantify and predict treatment outcomes. Methods: Bibliographic databases were searched by two independent reviewers up to 22 April 2019. Studies were included if the focus was on muscle synergies of the lower limbs during walking, obtained by a matrix factorization algorithm, in children with CP. Results: The majority (n = 12) of the 16 included studies found that children with CP recruited fewer muscle synergies during walking compared to TD children, and several studies (n = 8) showed that either the spatial or temporal structure of the muscle synergies differed between children with CP and TD children. Variability within and between subjects was larger in children with CP than in TD children, especially in more involved children. Muscle synergy characteristics before treatments to improve walking function could predict treatment outcomes (n = 3). Only minimal changes in synergies were found after treatment. Conclusions: The findings in this systematic review support the idea that children with CP use a simpler motor control strategy compared to TD children. The use of muscle synergy analysis as a clinical tool to quantify altered neuromuscular control and predict clinical outcomes seems promising. Further investigation on this topic is necessary, and the use of muscle synergies as a target for development of novel therapies in children with CP could be explored.
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Affiliation(s)
- Annike Bekius
- Department of Human Movement Sciences, Amsterdam Movement Sciences, Institute of Brain and Behavior Amsterdam, Vrije Universiteit Amsterdam, Amsterdam, Netherlands.,Department of Rehabilitation Medicine, Amsterdam Movement Sciences, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam, Netherlands
| | - Margit M Bach
- Department of Human Movement Sciences, Amsterdam Movement Sciences, Institute of Brain and Behavior Amsterdam, Vrije Universiteit Amsterdam, Amsterdam, Netherlands
| | - Marjolein M van der Krogt
- Department of Rehabilitation Medicine, Amsterdam Movement Sciences, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam, Netherlands
| | - Ralph de Vries
- Medical Library, Vrije Universiteit Amsterdam, Amsterdam, Netherlands
| | - Annemieke I Buizer
- Department of Rehabilitation Medicine, Amsterdam Movement Sciences, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam, Netherlands
| | - Nadia Dominici
- Department of Human Movement Sciences, Amsterdam Movement Sciences, Institute of Brain and Behavior Amsterdam, Vrije Universiteit Amsterdam, Amsterdam, Netherlands
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Nuckols RW, Sawicki GS. Impact of elastic ankle exoskeleton stiffness on neuromechanics and energetics of human walking across multiple speeds. J Neuroeng Rehabil 2020; 17:75. [PMID: 32539840 PMCID: PMC7294672 DOI: 10.1186/s12984-020-00703-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2020] [Accepted: 05/21/2020] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Elastic ankle exoskeletons with intermediate stiffness springs in parallel with the human plantarflexors can reduce the metabolic cost of walking by ~ 7% at 1.25 m s- 1. In a move toward 'real-world' application, we examined whether the unpowered approach has metabolic benefit across a range of walking speeds, and if so, whether the optimal exoskeleton stiffness was speed dependent. We hypothesized that, for any walking speed, there would be an optimal ankle exoskeleton stiffness - not too compliant and not too stiff - that minimizes the user's metabolic cost. In addition, we expected the optimal stiffness to increase with walking speed. METHODS Eleven participants walked on a level treadmill at 1.25, 1.50, and 1.75 m s- 1 while we used a state-of-the-art exoskeleton emulator to apply bilateral ankle exoskeleton assistance at five controlled rotational stiffnesses (kexo = 0, 50, 100, 150, 250 Nm rad- 1). We measured metabolic cost, lower-limb joint mechanics, and EMG of muscles crossing the ankle, knee, and hip. RESULTS Metabolic cost was significantly reduced at the lowest exoskeleton stiffness (50 Nm rad- 1) for assisted walking at both 1.25 (4.2%; p = 0.0162) and 1.75 m s- 1 (4.7%; p = 0.0045). At these speeds, the metabolically optimal exoskeleton stiffness provided peak assistive torques of ~ 0.20 Nm kg- 1 that resulted in reduced biological ankle moment of ~ 12% and reduced soleus muscle activity of ~ 10%. We found no stiffness that could reduce the metabolic cost of walking at 1.5 m s- 1. Across all speeds, the non-weighted sum of soleus and tibialis anterior activation rate explained the change in metabolic rate due to exoskeleton assistance (p < 0.05; R2 > 0.56). CONCLUSIONS Elastic ankle exoskeletons with low rotational stiffness reduce users' metabolic cost of walking at slow and fast but not intermediate walking speed. The relationship between the non-weighted sum of soleus and tibialis activation rate and metabolic cost (R2 > 0.56) indicates that muscle activation may drive metabolic demand. Future work using simulations and ultrasound imaging will get 'under the skin' and examine the interaction between exoskeleton stiffness and plantarflexor muscle dynamics to better inform stiffness selection in human-machine systems.
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Affiliation(s)
- Richard W Nuckols
- Joint Department of Biomedical Engineering, UNC Chapel Hill and NC State University, Raleigh, NC, USA.
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, 02138, USA.
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA, 02138, USA.
| | - Gregory S Sawicki
- Joint Department of Biomedical Engineering, UNC Chapel Hill and NC State University, Raleigh, NC, USA.
- George W. Woodruff School of Mechanical Engineering and School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, 30332, USA.
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Stirling L, Kelty-Stephen D, Fineman R, Jones MLH, Daniel Park BK, Reed MP, Parham J, Choi HJ. Static, Dynamic, and Cognitive Fit of Exosystems for the Human Operator. HUMAN FACTORS 2020; 62:424-440. [PMID: 32004106 DOI: 10.1177/0018720819896898] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
OBJECTIVE To define static, dynamic, and cognitive fit and their interactions as they pertain to exosystems and to document open research needs in using these fit characteristics to inform exosystem design. BACKGROUND Initial exosystem sizing and fit evaluations are currently based on scalar anthropometric dimensions and subjective assessments. As fit depends on ongoing interactions related to task setting and user, attempts to tailor equipment have limitations when optimizing for this limited fit definition. METHOD A targeted literature review was conducted to inform a conceptual framework defining three characteristics of exosystem fit: static, dynamic, and cognitive. Details are provided on the importance of differentiating fit characteristics for developing exosystems. RESULTS Static fit considers alignment between human and equipment and requires understanding anthropometric characteristics of target users and geometric equipment features. Dynamic fit assesses how the human and equipment move and interact with each other, with a focus on the relative alignment between the two systems. Cognitive fit considers the stages of human-information processing, including somatosensation, executive function, and motor selection. Human cognitive capabilities should remain available to process task- and stimulus-related information in the presence of an exosystem. Dynamic and cognitive fit are operationalized in a task-specific manner, while static fit can be considered for predefined postures. CONCLUSION A deeper understanding of how an exosystem fits an individual is needed to ensure good human-system performance. Development of methods for evaluating different fit characteristics is necessary. APPLICATION Methods are presented to inform exosystem evaluation across physical and cognitive characteristics.
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Affiliation(s)
| | | | - Richard Fineman
- 2167 Harvard-MIT Health Science and Technology Program, Cambridge, MA, USA
| | - Monica L H Jones
- 1259 University of Michigan Transportation Research Institute, Ann Arbor, USA
| | | | - Matthew P Reed
- 1259 University of Michigan Transportation Research Institute, Ann Arbor, USA
| | - Joseph Parham
- 155353 U.S. Army Combat Capabilities Development Command Soldier Center, Natick, MA, USA
| | - Hyeg Joo Choi
- 155353 U.S. Army Combat Capabilities Development Command Soldier Center, Natick, MA, USA
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31
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Nelson AJ, Hall PT, Saul KR, Crouch DL. Effect of Mechanically Passive, Wearable Shoulder Exoskeletons on Muscle Output During Dynamic Upper Extremity Movements: A Computational Simulation Study. J Appl Biomech 2020; 36:59-67. [PMID: 31968306 DOI: 10.1123/jab.2018-0369] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Revised: 12/12/2019] [Accepted: 12/12/2019] [Indexed: 10/27/2023]
Abstract
Wearable passive (ie, spring powered) shoulder exoskeletons could reduce muscle output during motor tasks to help prevent or treat shoulder musculoskeletal disorders. However, most wearable passive shoulder exoskeletons have been designed and evaluated for static tasks, so it is unclear how they affect muscle output during dynamic tasks. The authors used a musculoskeletal model and Computed Muscle Control optimization to estimate muscle output with and without a wearable passive shoulder exoskeleton during 2 simulated dynamic tasks: abduction and upward reach. To an existing upper extremity musculoskeletal model, the authors added an exoskeleton model with 3-dimensional representations of the exoskeleton components, including a spring, cam wheel, force-transmitting shoulder cable, and wrapping surfaces that permitted the shoulder cable to wrap over the shoulder. The exoskeleton reduced net muscle-generated moments in positive shoulder elevation by 28% and 62% during the abduction and upward reach, respectively. However, muscle outputs (joint moments and muscle effort) were higher with the exoskeleton than without at some points of the movement. Muscle output was higher with the exoskeleton because the exoskeleton moment opposed the muscle-generated moment in some postures. The results of this study highlight the importance of evaluating muscle output for passive exoskeletons designed to support dynamic movements to ensure that the exoskeletons assist, rather than impede, movement.
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Affiliation(s)
- Allison J Nelson
- University of Tennessee
- Virginia Polytechnic Institute and State University
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32
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Sawicki GS, Beck ON, Kang I, Young AJ. The exoskeleton expansion: improving walking and running economy. J Neuroeng Rehabil 2020; 17:25. [PMID: 32075669 PMCID: PMC7029455 DOI: 10.1186/s12984-020-00663-9] [Citation(s) in RCA: 139] [Impact Index Per Article: 34.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Accepted: 02/13/2020] [Indexed: 11/10/2022] Open
Abstract
Since the early 2000s, researchers have been trying to develop lower-limb exoskeletons that augment human mobility by reducing the metabolic cost of walking and running versus without a device. In 2013, researchers finally broke this 'metabolic cost barrier'. We analyzed the literature through December 2019, and identified 23 studies that demonstrate exoskeleton designs that improved human walking and running economy beyond capable without a device. Here, we reviewed these studies and highlighted key innovations and techniques that enabled these devices to surpass the metabolic cost barrier and steadily improve user walking and running economy from 2013 to nearly 2020. These studies include, physiologically-informed targeting of lower-limb joints; use of off-board actuators to rapidly prototype exoskeleton controllers; mechatronic designs of both active and passive systems; and a renewed focus on human-exoskeleton interface design. Lastly, we highlight emerging trends that we anticipate will further augment wearable-device performance and pose the next grand challenges facing exoskeleton technology for augmenting human mobility.
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Affiliation(s)
- Gregory S Sawicki
- The George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA.
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA.
- Institute for Robotics and Intelligent Machines, Georgia Institute of Technology, Atlanta, GA, USA.
| | - Owen N Beck
- The George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA
| | - Inseung Kang
- The George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA
| | - Aaron J Young
- The George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA.
- Institute for Robotics and Intelligent Machines, Georgia Institute of Technology, Atlanta, GA, USA.
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Tan CK, Kadone H, Miura K, Abe T, Koda M, Yamazaki M, Sankai Y, Suzuki K. Muscle Synergies During Repetitive Stoop Lifting With a Bioelectrically-Controlled Lumbar Support Exoskeleton. Front Hum Neurosci 2019; 13:142. [PMID: 31114492 PMCID: PMC6503089 DOI: 10.3389/fnhum.2019.00142] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 04/11/2019] [Indexed: 12/27/2022] Open
Abstract
Lower back problems are common in the world, which leads to the development of various lumbar support exoskeletons to alleviate this problem. In general, previous studies evaluating lumbar support devices quantified assistance by reporting the reduction in back muscle activity and perceived fatigue. However, despite the beneficial effects of such devices, the effects of using such exoskeletons on muscle coordination are not well-studied. In this study, we examined the short-term change in muscle coordination of subjects using a bioelectrically-controlled lumbar support exoskeleton in a fatiguing stoop lifting task with muscle synergy analysis. Results indicate that muscle coordination changes were dominated by changes in timing coefficients, with minimal change in muscle synergy vectors. Analysis on muscle coordination changes would be useful to design future generations of exoskeletons.
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Affiliation(s)
- Chun Kwang Tan
- Artificial Intelligence Laboratory, University of Tsukuba, Tsukuba, Japan
| | - Hideki Kadone
- Center for Innovative Medicine and Engineering, University of Tsukuba Hospital, Tsukuba, Japan
| | - Kousei Miura
- Department of Orthopaedic Surgery, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Tetsuya Abe
- Department of Orthopaedic Surgery, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Masao Koda
- Department of Orthopaedic Surgery, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Masashi Yamazaki
- Department of Orthopaedic Surgery, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Yoshiyuki Sankai
- Center for Cybernics Research, University of Tsukuba, Tsukuba, Japan.,Faculty of Engineering, University of Tsukuba, Tsukuba, Japan
| | - Kenji Suzuki
- Artificial Intelligence Laboratory, University of Tsukuba, Tsukuba, Japan.,Center for Cybernics Research, University of Tsukuba, Tsukuba, Japan.,Faculty of Engineering, University of Tsukuba, Tsukuba, Japan
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Shuman BR, Goudriaan M, Desloovere K, Schwartz MH, Steele KM. Muscle synergies demonstrate only minimal changes after treatment in cerebral palsy. J Neuroeng Rehabil 2019; 16:46. [PMID: 30925882 PMCID: PMC6441188 DOI: 10.1186/s12984-019-0502-3] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 02/22/2019] [Indexed: 12/23/2022] Open
Abstract
Background Children with cerebral palsy (CP) have altered synergies compared to typically-developing peers, reflecting different neuromuscular control strategies used to move. While these children receive a variety of treatments to improve gait, whether synergies change after treatment, or are associated with treatment outcomes, remains unknown. Methods We evaluated synergies for 147 children with CP before and after three common treatments: botulinum toxin type-A injection (n = 52), selective dorsal rhizotomy (n = 38), and multi-level orthopaedic surgery (n = 57). Changes in synergy complexity were measured by the number of synergies required to explain > 90% of the total variance in electromyography data and total variance accounted for by one synergy. Synergy weights and activations before and after treatment were compared using the cosine similarity relative to average synergies of 31 typically-developing (TD) peers. Results There were minimal changes in synergies after treatment despite changes in walking patterns. Number of synergies did not change significantly for any treatment group. Total variance accounted for by one synergy increased (i.e., moved further from TD peers) after botulinum toxin type-A injection (1.3%) and selective dorsal rhizotomy (1.9%), but the change was small. Synergy weights did not change for any treatment group (average 0.001 ± 0.10), but synergy activations after selective dorsal rhizotomy did change and were less similar to TD peers (− 0.03 ± 0.07). Only changes in synergy activations were associated with changes in gait kinematics or walking speed after treatment. Children with synergy activations more similar to TD peers after treatment had greater improvements in gait. Conclusions While many of these children received significant surgical procedures and prolonged rehabilitation, the minimal changes in synergies after treatment highlight the challenges in altering neuromuscular control in CP. Development of treatment strategies that directly target impaired control or are optimized to an individual’s unique control may be required to improve walking function.
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Affiliation(s)
- Benjamin R Shuman
- Department of Mechanical Engineering, University of Washington, Stevens Way, Box 352600, Seattle, WA, 98195, USA
| | - Marije Goudriaan
- Department of Human Movement Sciences, VU university, Amsterdam, the Netherlands.,Department of Rehabilitation Science, KU Leuven, Leuven, Belgium
| | - Kaat Desloovere
- Department of Rehabilitation Science, KU Leuven, Leuven, Belgium.,Clinical Motion Analysis Laboratory, University Hospitals Leuven Campus Pellenberg, Pellenberg, Belgium
| | - Michael H Schwartz
- James R. Gage Center for Gait & Motion Analysis, Gillette Children's Specialty Healthcare, St. Paul, MN, USA.,Department of Orthopaedic Surgery, University of Minnesota, Minneapolis, MN, USA
| | - Katherine M Steele
- Department of Mechanical Engineering, University of Washington, Stevens Way, Box 352600, Seattle, WA, 98195, USA.
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Li Z, Liu H, Yin Z, Chen K. Muscle Synergy Alteration of Human During Walking With Lower Limb Exoskeleton. Front Neurosci 2019; 12:1050. [PMID: 30760972 PMCID: PMC6361853 DOI: 10.3389/fnins.2018.01050] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Accepted: 12/24/2018] [Indexed: 11/13/2022] Open
Abstract
Muscle synergy reflects inherent coordination patterns of muscle groups as the human body finishes required movements. It may be still unknown whether the original muscle synergy of subjects may alter or not when exoskeletons are put on during their normal walking activities. This paper reports experimental results and presents analysis on muscle synergy from 17 able-bodied subjects with and without lower-limb exoskeletons when they performed normal walking tasks. The electromyography (EMG) signals of the tibialis anterior (TA), soleus (SOL), lateral gastrocnemius (GAS), vastus medialis oblique (VMO), vastus lateralis oblique (VLO), biceps femoris (BICE), semitendinosus (SEMI), and rectus femoris (RECT) muscles were extracted to obtain the muscle synergy. The quantitative results show that, when the subjects wore exoskeletons to walk normally, their mean muscle synergy changed from when they walked without exoskeletons. When the subjects walked with and without exoskeletons, statistically significant differences on sub-patterns of the muscles' synergies between the corresponding two groups could be found.
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Affiliation(s)
- Zhan Li
- School of Automation Engineering, University of Electronic Science and Technology of China, Chengdu, China
| | - Huxian Liu
- School of Automation Engineering, University of Electronic Science and Technology of China, Chengdu, China
| | - Ziguang Yin
- School of Automation Engineering, University of Electronic Science and Technology of China, Chengdu, China
| | - Kejia Chen
- School of Automation Engineering, University of Electronic Science and Technology of China, Chengdu, China
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36
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Aoi S, Ohashi T, Bamba R, Fujiki S, Tamura D, Funato T, Senda K, Ivanenko Y, Tsuchiya K. Neuromusculoskeletal model that walks and runs across a speed range with a few motor control parameter changes based on the muscle synergy hypothesis. Sci Rep 2019; 9:369. [PMID: 30674970 PMCID: PMC6344546 DOI: 10.1038/s41598-018-37460-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 12/07/2018] [Indexed: 01/14/2023] Open
Abstract
Humans walk and run, as well as change their gait speed, through the control of their complicated and redundant musculoskeletal system. These gaits exhibit different locomotor behaviors, such as a double-stance phase in walking and flight phase in running. The complex and redundant nature of the musculoskeletal system and the wide variation in locomotion characteristics lead us to imagine that the motor control strategies for these gaits, which remain unclear, are extremely complex and differ from one another. It has been previously proposed that muscle activations may be generated by linearly combining a small set of basic pulses produced by central pattern generators (muscle synergy hypothesis). This control scheme is simple and thought to be shared between walking and running at different speeds. Demonstrating that this control scheme can generate walking and running and change the speed is critical, as bipedal locomotion is dynamically challenging. Here, we provide such a demonstration by using a motor control model with 69 parameters developed based on the muscle synergy hypothesis. Specifically, we show that it produces both walking and running of a human musculoskeletal model by changing only seven key motor control parameters. Furthermore, we show that the model can walk and run at different speeds by changing only the same seven parameters based on the desired speed. These findings will improve our understanding of human motor control in locomotion and provide guiding principles for the control design of wearable exoskeletons and prostheses.
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Affiliation(s)
- Shinya Aoi
- Department of Aeronautics and Astronautics, Graduate School of Engineering, Kyoto University, Kyoto daigaku-Katsura, Nishikyo-ku, Kyoto, 615-8540, Japan.
| | - Tomohiro Ohashi
- Department of Aeronautics and Astronautics, Graduate School of Engineering, Kyoto University, Kyoto daigaku-Katsura, Nishikyo-ku, Kyoto, 615-8540, Japan
| | - Ryoko Bamba
- Department of Aeronautics and Astronautics, Graduate School of Engineering, Kyoto University, Kyoto daigaku-Katsura, Nishikyo-ku, Kyoto, 615-8540, Japan
| | - Soichiro Fujiki
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902, Japan
| | - Daiki Tamura
- Department of Aeronautics and Astronautics, Graduate School of Engineering, Kyoto University, Kyoto daigaku-Katsura, Nishikyo-ku, Kyoto, 615-8540, Japan
| | - Tetsuro Funato
- Department of Mechanical Engineering and Intelligent Systems, Graduate School of Informatics and Engineering, The University of Electro-Communications, 1-5-1 Choufugaoka, Choufu-shi, Tokyo, 182-8585, Japan
| | - Kei Senda
- Department of Aeronautics and Astronautics, Graduate School of Engineering, Kyoto University, Kyoto daigaku-Katsura, Nishikyo-ku, Kyoto, 615-8540, Japan
| | - Yury Ivanenko
- Laboratory of Neuromotor Physiology, IRCCS Santa Lucia Foundation, 00179, Rome, Italy
| | - Kazuo Tsuchiya
- Department of Aeronautics and Astronautics, Graduate School of Engineering, Kyoto University, Kyoto daigaku-Katsura, Nishikyo-ku, Kyoto, 615-8540, Japan
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Ji Q, Wang F, Zhou R, Li J, Wang J, Ye X. Assessment of ankle muscle activation by muscle synergies in healthy and post-stroke gait. Physiol Meas 2018; 39:045003. [PMID: 29488903 DOI: 10.1088/1361-6579/aab2ed] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
OBJECTIVE Impaired ankle dorsal and plantar flexor function is a frequent sequela of stroke. A better assessment of ankle muscle activation would be highly significant for stroke rehabilitation. The challenge in implementing current electromyography (EMG)-based assessments is due to problems with the variability and individuality of ankle muscle EMG profiles during walking. We have been studying a new technique using the muscle synergy method to quantify the characteristics that underlie ankle muscle activation to address this issue. APPROACH We processed surface EMG signals from ankle muscles and gait parameters collected from 20 healthy and 22 post-stroke subjects during walking. A non-negative matrix factorization algorithm was used to extract muscle synergies. MAIN RESULTS Our results suggest a featured muscle synergy structure (R = 0.84, 95% CI: 0.83-0.85) underlying ankle muscle activation in both healthy and post-stroke subjects. The structure of the featured muscle synergy was robust in the same subjects across different conditions in the healthy group (R = 0.97, 95% CI: 0.96-0.98) and the post-stroke group (R = 0.95, 95% CI: 0.88-0.97). Compared to the stroke group, the synergy patterns of healthy subjects showed better regularity and higher inter-subject similarity (P = 0.001). In addition, the results of muscle synergies were indicative of locomotor performance. SIGNIFICANCE The innovative quantitative results of this study can help us to better understand ankle muscle activation and will be a reference for clinical assessments and intervention studies.
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Affiliation(s)
- Qing Ji
- College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou, People's Republic of China
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38
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Jacobs DA, Koller JR, Steele KM, Ferris DP. Motor modules during adaptation to walking in a powered ankle exoskeleton. J Neuroeng Rehabil 2018; 15:2. [PMID: 29298705 PMCID: PMC5751608 DOI: 10.1186/s12984-017-0343-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 12/13/2017] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Modules of muscle recruitment can be extracted from electromyography (EMG) during motions, such as walking, running, and swimming, to identify key features of muscle coordination. These features may provide insight into gait adaptation as a result of powered assistance. The aim of this study was to investigate the changes (module size, module timing and weighting patterns) of surface EMG data during assisted and unassisted walking in an powered, myoelectric, ankle-foot orthosis (ankle exoskeleton). METHODS Eight healthy subjects wore bilateral ankle exoskeletons and walked at 1.2 m/s on a treadmill. In three training sessions, subjects walked for 40 min in two conditions: unpowered (10 min) and powered (30 min). During each session, we extracted modules of muscle recruitment via nonnegative matrix factorization (NNMF) from the surface EMG signals of ten muscles in the lower limb. We evaluated reconstruction quality for each muscle individually using R2 and normalized root mean squared error (NRMSE). We hypothesized that the number of modules needed to reconstruct muscle data would be the same between conditions and that there would be greater similarity in module timings than weightings. RESULTS Across subjects, we found that six modules were sufficient to reconstruct the muscle data for both conditions, suggesting that the number of modules was preserved. The similarity of module timings and weightings between conditions was greater then random chance, indicating that muscle coordination was also preserved. Motor adaptation during walking in the exoskeleton was dominated by changes in the module timings rather than module weightings. The segment number and the session number were significant fixed effects in a linear mixed-effect model for the increase in R2 with time. CONCLUSIONS Our results show that subjects walking in a exoskeleton preserved the number of modules and the coordination of muscles within the modules across conditions. Training (motor adaptation within the session and motor skill consolidation across sessions) led to improved consistency of the muscle patterns. Subjects adapted primarily by changing the timing of their muscle patterns rather than the weightings of muscles in the modules. The results of this study give new insight into strategies for muscle recruitment during adaptation to a powered ankle exoskeleton.
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Affiliation(s)
- Daniel A. Jacobs
- Department of Mechanical Engineering, Temple University, 1947 N. 12th Street, Philadelphia, PA USA
| | - Jeffrey R. Koller
- Department of Mechanical Engineering, University of Washington, 3900 E Stevens Way NE, Seattle, WA USA
| | - Katherine M. Steele
- Department of Mechanical Engineering, University of Michigan, 2350 Hayward St, Ann Arbor, MI USA
| | - Daniel P. Ferris
- Department of Biomedical Engineering, University of Florida, 1275 Center Drive, Gainesville, FL USA
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