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Andrade RL, Figueiredo J, Fonseca P, Vilas-Boas JP, Silva MT, Santos CP. Human-Robot Joint Misalignment, Physical Interaction, and Gait Kinematic Assessment in Ankle-Foot Orthoses. SENSORS (BASEL, SWITZERLAND) 2023; 24:246. [PMID: 38203110 PMCID: PMC10781370 DOI: 10.3390/s24010246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Revised: 12/24/2023] [Accepted: 12/26/2023] [Indexed: 01/12/2024]
Abstract
Lower limb exoskeletons and orthoses have been increasingly used to assist the user during gait rehabilitation through torque transmission and motor stability. However, the physical human-robot interface (HRi) has not been properly addressed. Current orthoses lead to spurious forces at the HRi that cause adverse effects and high abandonment rates. This study aims to assess and compare, in a holistic approach, human-robot joint misalignment and gait kinematics in three fixation designs of ankle-foot orthoses (AFOs). These are AFOs with a frontal shin guard (F-AFO), lateral shin guard (L-AFO), and the ankle modulus of the H2 exoskeleton (H2-AFO). An experimental protocol was implemented to assess misalignment, fixation displacement, pressure interactions, user-perceived comfort, and gait kinematics during walking with the three AFOs. The F-AFO showed reduced vertical misalignment (peak of 1.37 ± 0.90 cm, p-value < 0.05), interactions (median pressures of 0.39-3.12 kPa), and higher user-perceived comfort (p-value < 0.05) when compared to H2-AFO (peak misalignment of 2.95 ± 0.64 and pressures ranging from 3.19 to 19.78 kPa). F-AFO also improves the L-AFO in pressure (median pressures ranging from 8.64 to 10.83 kPa) and comfort (p-value < 0.05). All AFOs significantly modified hip joint angle regarding control gait (p-value < 0.01), while the H2-AFO also affected knee joint angle (p-value < 0.01) and gait spatiotemporal parameters (p-value < 0.05). Overall, findings indicate that an AFO with a frontal shin guard and a sports shoe is effective at reducing misalignment and pressure at the HRI, increasing comfort with slight changes in gait kinematics.
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Affiliation(s)
- Ricardo Luís Andrade
- Center for MicroElectroMechanical Systems (CMEMS), University of Minho, 4800-058 Guimarães, Portugal
| | - Joana Figueiredo
- Center for MicroElectroMechanical Systems (CMEMS), University of Minho, 4800-058 Guimarães, Portugal
- LABBELS—Associate Laboratory, 4710-057 Braga/4800-058 Guimarães, Portugal
| | - Pedro Fonseca
- Porto Biomechanics Laboratory (LABIOMEP), University of Porto, 4200-450 Porto, Portugal; (P.F.); (J.P.V.-B.)
| | - João P. Vilas-Boas
- Porto Biomechanics Laboratory (LABIOMEP), University of Porto, 4200-450 Porto, Portugal; (P.F.); (J.P.V.-B.)
- Centre of Research, Education, Innovation and Intervention in Sport (CIFI2D), Faculty of Sport, University of Porto, 4200-450 Porto, Portugal
| | - Miguel T. Silva
- IDMEC, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais 1, 1049-001 Lisbon, Portugal;
| | - Cristina P. Santos
- Center for MicroElectroMechanical Systems (CMEMS), University of Minho, 4800-058 Guimarães, Portugal
- LABBELS—Associate Laboratory, 4710-057 Braga/4800-058 Guimarães, Portugal
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2
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Hybart R, Ferris D. Gait variability of outdoor vs treadmill walking with bilateral robotic ankle exoskeletons under proportional myoelectric control. PLoS One 2023; 18:e0294241. [PMID: 37956157 PMCID: PMC10642814 DOI: 10.1371/journal.pone.0294241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Accepted: 10/27/2023] [Indexed: 11/15/2023] Open
Abstract
Lower limb robotic exoskeletons are often studied in the context of steady-state treadmill walking in laboratory environments. However, the end goal of these devices is often adoption into our everyday lives. To move outside of the laboratory, there is a need to study exoskeletons in real world, complex environments. One way to study the human-machine interaction is to look at how the exoskeleton affects the user's gait. In this study we assessed changes in gait spatiotemporal variability when using a robotic ankle exoskeleton under proportional myoelectric control both inside on a treadmill and outside overground. We hypothesized that walking with the exoskeletons would not lead to significant changes in variability inside on a treadmill or outside compared to not using the exoskeletons. In addition, we hypothesized that walking outside would lead to higher variability both with and without the exoskeletons compared to treadmill walking. In support of our hypothesis, we found significantly higher coefficients of variation of stride length, stance time, and swing time when walking outside both with and without the exoskeleton. We found a significantly higher variability when using the exoskeletons inside on the treadmill, but we did not see significantly higher variability when walking outside overground. The value of this study to the literature is that it emphasizes the importance of studying exoskeletons in the environment in which they are meant to be used. By looking at only indoor gait spatiotemporal measures, we may have assumed that the exoskeletons led to higher variability which may be unsafe for certain target populations. In the context of the literature, we show that variability due to robotic ankle exoskeletons under proportional myoelectric control does not elicit different changes in stride time variability than previously found in other daily living tasks (uneven terrain, load carriage, or cognitive tasks).
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Affiliation(s)
- Rachel Hybart
- J. Crayton Pruitt Department of Biomedical Engineering, University of Florida, Gainesville, Florida, United States of America
| | - Daniel Ferris
- J. Crayton Pruitt Department of Biomedical Engineering, University of Florida, Gainesville, Florida, United States of America
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3
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Andrade RM, Sapienza S, Mohebbi A, Fabara EE, Bonato P. Overground Walking With a Transparent Exoskeleton Shows Changes in Spatiotemporal Gait Parameters. IEEE JOURNAL OF TRANSLATIONAL ENGINEERING IN HEALTH AND MEDICINE 2023; 12:182-193. [PMID: 38088995 PMCID: PMC10712666 DOI: 10.1109/jtehm.2023.3323381] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 07/07/2023] [Accepted: 09/07/2023] [Indexed: 12/18/2023]
Abstract
Lower-limb gait training (GT) exoskeletons have been successfully used in rehabilitation programs to overcome the burden of locomotor impairment. However, providing suitable net interaction torques to assist patient movements is still a challenge. Previous transparent operation approaches have been tested in treadmill-based GT exoskeletons to improve user-robot interaction. However, it is not yet clear how a transparent lower-limb GT system affects user's gait kinematics during overground walking, which unlike treadmill-based systems, requires active participation of the subjects to maintain stability. In this study, we implemented a transparent operation strategy on the ExoRoboWalker, an overground GT exoskeleton, to investigate its effect on the user's gait. The approach employs a feedback zero-torque controller with feedforward compensation for the exoskeleton's dynamics and actuators' impedance. We analyzed the data of five healthy subjects walking overground with the exoskeleton in transparent mode (ExoTransp) and non-transparent mode (ExoOff) and walking without exoskeleton (NoExo). The transparent controller reduced the user-robot interaction torque and improved the user's gait kinematics relative to ExoOff. No significant difference in stride length is observed between ExoTransp and NoExo (p = 0.129). However, the subjects showed a significant difference in cadence between ExoTransp (50.9± 1.1 steps/min) and NoExo (93.7 ± 8.7 steps/min) (p = 0.015), but not between ExoTransp and ExoOff (p = 0.644). Results suggest that subjects wearing the exoskeleton adjust their gait as in an attention-demanding task changing the spatiotemporal gait characteristics likely to improve gait balance.
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Affiliation(s)
- Rafhael M. Andrade
- Department of Mechanical EngineeringUniversidade Federal do Espirito SantoVitóriaEspirito Santo29075Brazil
- Department of Physical Medicine and RehabilitationHarvard Medical SchoolSpaulding Rehabilitation HospitalCharlestownMA02129USA
| | - Stefano Sapienza
- Department of Physical Medicine and RehabilitationHarvard Medical SchoolSpaulding Rehabilitation HospitalCharlestownMA02129USA
| | - Abolfazl Mohebbi
- Department of Mechanical EngineeringPolytechnique MontrealMontréalQCH3T 1J4Canada
| | - Eric E. Fabara
- Department of Physical Medicine and RehabilitationHarvard Medical SchoolSpaulding Rehabilitation HospitalCharlestownMA02129USA
| | - Paolo Bonato
- Department of Physical Medicine and RehabilitationHarvard Medical SchoolSpaulding Rehabilitation HospitalCharlestownMA02129USA
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Yun SS, Bundschu CW, Cho KJ. A Hybrid Anchoring Technology Composed of Reinforced Flexible Shells for a Knee Unloading Exosuit. Soft Robot 2023; 10:873-883. [PMID: 37155198 DOI: 10.1089/soro.2021.0223] [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: 05/10/2023] Open
Abstract
Soft robotic wearables have emerged as an ergonomic alternative to rigid robotic wearables, commonly utilizing tension-based actuation systems. However, their soft structure's natural tendency to buckle limits their use for compression bearing applications. This study presents reinforced flexible shell (RFS) anchoring, a compliant, low-profile, ergonomic wearable platform capable of high compression resistance. RFS anchors are fabricated with soft and semirigid materials that typically buckle under compressive loads. Buckling is overcome using the wearer's leg as a support structure, reinforcing the shells with straps, and minimizing the space between the shells and the wearer's skin-enabling force transmission orders of magnitude larger. RFS anchoring performance was evaluated comparatively by examining the shift-deformation profiles of three identically designed braces fabricated with different materials: rigid, strapped RFS, and unstrapped RFS. The unstrapped RFS severely deformed before 200 N of force could be applied. The strapped RFS successfully supported 200 N of force and exhibited a nearly identical transient shift-deformation profile with the rigid brace condition. RFS anchoring technology was applied to a compression-resistant hybrid exosuit, Exo-Unloader, for knee osteoarthritis. Exo-Unloader utilizes a tendon-driven linear sliding actuation system that unloads the medial and lateral compartments of the knee. Exo-Unloader can deliver 200 N of unloading force without deforming, as indicted by its similar transient shift-deformation profile with a rigid unloader baseline. Although rigid braces effectively withstand and transmit high compressive loads, they lack compliance; RFS anchoring technology expands the application of soft and flexible materials to compression-based wearable assistive systems.
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Affiliation(s)
- Sung-Sik Yun
- Soft Robotics Research Center, Seoul National University, Seoul, Republic of Korea
- Department of Mechanical Engineering, Institute of Advanced Machines and Design, Institute of Engineering Research, Seoul National University, Seoul, Republic of Korea
| | - Christian William Bundschu
- Soft Robotics Research Center, Seoul National University, Seoul, Republic of Korea
- Department of Mechanical Engineering, Institute of Advanced Machines and Design, Institute of Engineering Research, Seoul National University, Seoul, Republic of Korea
| | - Kyu-Jin Cho
- Soft Robotics Research Center, Seoul National University, Seoul, Republic of Korea
- Department of Mechanical Engineering, Institute of Advanced Machines and Design, Institute of Engineering Research, Seoul National University, Seoul, Republic of Korea
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Sun M, Bacek T, Kulic D, McGinley J, Oetomo D, Tan Y. Modelling Physical Human-Robot Interface with Different Users, Cuffs, and Strapping Pressures: A Case Study. IEEE Int Conf Rehabil Robot 2023; 2023:1-6. [PMID: 37941249 DOI: 10.1109/icorr58425.2023.10304754] [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
Assisting persons during physical therapy or augmenting their performance often requires precise delivery of an intervention. Robotic devices are perfectly placed to do so, but their intervention highly depends on the physical human-robot connection. The inherent compliance in the connection leads to delays and losses in bi-directional power transmission and can lead to human-robot joint axes misalignment. This is often neglected in the literature by assuming a rigid connection and has a negative impact on the intervention's effectiveness and robustness. This paper presents the preliminary results of a study that aims to close that gap. The study investigates what model forms and parameters best capture human-robot connection dynamics across different persons, connection designs (cuffs), and cuff strapping pressures. The results show that the linear spring-damper model is the best compromise, but its parameters must be adjusted for each individual and different conditions separately.
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Sarajchi M, Sirlantzis K. Design and Control of a Single-Leg Exoskeleton with Gravity Compensation for Children with Unilateral Cerebral Palsy. SENSORS (BASEL, SWITZERLAND) 2023; 23:6103. [PMID: 37447953 DOI: 10.3390/s23136103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Revised: 06/21/2023] [Accepted: 06/27/2023] [Indexed: 07/15/2023]
Abstract
Children with cerebral palsy (CP) experience reduced quality of life due to limited mobility and independence. Recent studies have shown that lower-limb exoskeletons (LLEs) have significant potential to improve the walking ability of children with CP. However, the number of prototyped LLEs for children with CP is very limited, while no single-leg exoskeleton (SLE) has been developed specifically for children with CP. This study aims to fill this gap by designing the first size-adjustable SLE for children with CP aged 8 to 12, covering Gross Motor Function Classification System (GMFCS) levels I to IV. The exoskeleton incorporates three active joints at the hip, knee, and ankle, actuated by brushless DC motors and harmonic drive gears. Individuals with CP have higher metabolic consumption than their typically developed (TD) peers, with gravity being a significant contributing factor. To address this, the study designed a model-based gravity-compensator impedance controller for the SLE. A dynamic model of user and exoskeleton interaction based on the Euler-Lagrange formulation and following Denavit-Hartenberg rules was derived and validated in Simscape™ and Simulink® with remarkable precision. Additionally, a novel systematic simplification method was developed to facilitate dynamic modelling. The simulation results demonstrate that the controlled SLE can improve the walking functionality of children with CP, enabling them to follow predefined target trajectories with high accuracy.
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Affiliation(s)
| | - Konstantinos Sirlantzis
- School of Engineering, Technology and Design, Canterbury Christ Church University, Canterbury, CT1 1QU, UK
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Verdel D, Sahm G, Bruneau O, Berret B, Vignais N. A Trade-Off between Complexity and Interaction Quality for Upper Limb Exoskeleton Interfaces. SENSORS (BASEL, SWITZERLAND) 2023; 23:4122. [PMID: 37112463 PMCID: PMC10142870 DOI: 10.3390/s23084122] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Revised: 04/14/2023] [Accepted: 04/18/2023] [Indexed: 06/19/2023]
Abstract
Exoskeletons are among the most promising devices dedicated to assisting human movement during reeducation protocols and preventing musculoskeletal disorders at work. However, their potential is currently limited, partially because of a fundamental contradiction impacting their design. Indeed, increasing the interaction quality often requires the inclusion of passive degrees of freedom in the design of human-exoskeleton interfaces, which increases the exoskeleton's inertia and complexity. Thus, its control also becomes more complex, and unwanted interaction efforts can become important. In the present paper, we investigate the influence of two passive rotations in the forearm interface on sagittal plane reaching movements while keeping the arm interface unchanged (i.e., without passive degrees of freedom). Such a proposal represents a possible compromise between conflicting design constraints. The in-depth investigations carried out here in terms of interaction efforts, kinematics, electromyographic signals, and subjective feedback of participants all underscored the benefits of such a design. Therefore, the proposed compromise appears to be suitable for rehabilitation sessions, specific tasks at work, and future investigations into human movement using exoskeletons.
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Affiliation(s)
- Dorian Verdel
- Université Paris-Saclay, CIAMS, 91405 Orsay, France
- CIAMS, Université d’Orléans, 45100 Orléans, France
- LURPA, ENS Paris-Saclay, Université Paris-Saclay, 91190 Gif-sur-Yvette, France
| | - Guillaume Sahm
- Université Paris-Saclay, CIAMS, 91405 Orsay, France
- CIAMS, Université d’Orléans, 45100 Orléans, France
| | - Olivier Bruneau
- LURPA, ENS Paris-Saclay, Université Paris-Saclay, 91190 Gif-sur-Yvette, France
| | - Bastien Berret
- Université Paris-Saclay, CIAMS, 91405 Orsay, France
- CIAMS, Université d’Orléans, 45100 Orléans, France
| | - Nicolas Vignais
- Université Paris-Saclay, CIAMS, 91405 Orsay, France
- CIAMS, Université d’Orléans, 45100 Orléans, France
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Lindemann U, Krespach J, Daub U, Schneider M, Sczuka KS, Klenk J. Effect of a Passive Exosuit on Sit-to-Stand Performance in Geriatric Patients Measured by Body-Worn Sensors-A Pilot Study. SENSORS (BASEL, SWITZERLAND) 2023; 23:1032. [PMID: 36679828 PMCID: PMC9867217 DOI: 10.3390/s23021032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 01/13/2023] [Accepted: 01/14/2023] [Indexed: 06/17/2023]
Abstract
Standing up from a seated position is a prerequisite for any kind of physical mobility but many older persons have problems with the sit-to-stand (STS) transfer. There are several exosuits available for industrial work, which might be adapted to the needs of older persons to support STS transfers. However, objective measures to quantify and evaluate such systems are needed. The aim of this study was to quantify the possible support of an exosuit during the STS transfer of geriatric patients. Twenty-one geriatric patients with a median age of 82 years (1.-3.Q. 79-84 years) stood up at a normal pace (1) from a chair without using armrests, (2) with using armrests and (3) from a bed with pushing off, each condition with and without wearing an exosuit. Peak angular velocity of the thighs was measured by body-worn sensors. It was higher when standing up with exosuit support from a bed (92.6 (1.-3.Q. 84.3-116.2)°/s versus 79.7 (1.-3.Q. 74.6-98.2)°/s; p = 0.014) and from a chair with armrests (92.9 (1.-3.Q. 78.3-113.0)°/s versus 77.8 (1.-3.Q. 59.3-100.7)°/s; p = 0.089) compared to no support. There was no effect of the exosuit when standing up from a chair without using armrests. In general, it was possible to quantify the support of the exosuit using sensor-measured peak angular velocity. These results suggest that depending on the STS condition, an exosuit can support older persons during the STS transfer.
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Affiliation(s)
- Ulrich Lindemann
- Department of Clinical Gerontology, Robert-Bosch-Hospital, 70376 Stuttgart, Germany
| | - Jana Krespach
- Department of Clinical Gerontology, Robert-Bosch-Hospital, 70376 Stuttgart, Germany
| | - Urban Daub
- Biomechatronic Systems, Fraunhofer Institute for Manufacturing Engineering and Automation IPA, 70569 Stuttgart, Germany
| | - Marc Schneider
- Department of Clinical Gerontology, Robert-Bosch-Hospital, 70376 Stuttgart, Germany
| | - Kim S. Sczuka
- Department of Clinical Gerontology, Robert-Bosch-Hospital, 70376 Stuttgart, Germany
| | - Jochen Klenk
- Department of Clinical Gerontology, Robert-Bosch-Hospital, 70376 Stuttgart, Germany
- Institute of Epidemiology and Medical Biometry, Ulm University, 89081 Ulm, Germany
- Study Center Stuttgart, IB University of Health and Social Sciences, 70178 Stuttgart, Germany
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Scherb D, Wartzack S, Miehling J. Modelling the interaction between wearable assistive devices and digital human models-A systematic review. Front Bioeng Biotechnol 2023; 10:1044275. [PMID: 36704313 PMCID: PMC9872199 DOI: 10.3389/fbioe.2022.1044275] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Accepted: 12/21/2022] [Indexed: 01/11/2023] Open
Abstract
Exoskeletons, orthoses, exosuits, assisting robots and such devices referred to as wearable assistive devices are devices designed to augment or protect the human body by applying and transmitting force. Due to the problems concerning cost- and time-consuming user tests, in addition to the possibility to test different configurations of a device, the avoidance of a prototype and many more advantages, digital human models become more and more popular for evaluating the effects of wearable assistive devices on humans. The key indicator for the efficiency of assistance is the interface between device and human, consisting mainly of the soft biological tissue. However, the soft biological tissue is mostly missing in digital human models due to their rigid body dynamics. Therefore, this systematic review aims to identify interaction modelling approaches between wearable assistive devices and digital human models and especially to study how the soft biological tissue is considered in the simulation. The review revealed four interaction modelling approaches, which differ in their accuracy to recreate the occurring interactions in reality. Furthermore, within these approaches there are some incorporating the appearing relative motion between device and human body due to the soft biological tissue in the simulation. The influence of the soft biological tissue on the force transmission due to energy absorption on the other side is not considered in any publication yet. Therefore, the development of an approach to integrate the viscoelastic behaviour of soft biological tissue in the digital human models could improve the design of the wearable assistive devices and thus increase its efficiency and efficacy.
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Feasibility and Application of the B.E.A.T. Testbed for Assessing the Effects of Lower Limb Exoskeletons on Human Balance. ROBOTICS 2022. [DOI: 10.3390/robotics11060151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Assessing the performance of exoskeletons in assisting human balance is important for their design process. This study proposes a novel testbed, the B.E.A.T (Balance Evaluation Automated Testbed) to address this aim. We applied the B.E.A.T to evaluate how the presence of a lower limb exoskeleton influenced human balance. The B.E.A.T. consists of a robotic platform, standardized protocols, and performance indicators. Fifteen healthy subjects were enrolled and subjected to repeatable step-type ground perturbations in different directions using the multi-axis robotic platform. Each participant performed three trials, both with and without the exoskeleton (EXO and No-EXO conditions). Nine performance indicators, divided into kinematic and body stability indicators, were computed. The reliability of performance indicators was assessed by computing the Inter Class Correlation (ICC). The indicators showed good (0.60 ≤ ICC < 0.75) to excellent (ICC ≥ 0.75) reliability. The comparison between the EXO and No-EXO conditions revealed a significant increase in the joint range of motion and the center of pressure displacement while wearing the exoskeleton. The main differences between the EXO and No-EXO conditions were found in the range of motion of the knee joints, with an increment up to 17° in the sagittal plane.
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Yu S, Huang TH, Di Lallo A, Zhang S, Wang T, Fu Q, Su H. Bio-inspired design of a self-aligning, lightweight, and highly-compliant cable-driven knee exoskeleton. Front Hum Neurosci 2022; 16:1018160. [PMID: 36419645 PMCID: PMC9677347 DOI: 10.3389/fnhum.2022.1018160] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Accepted: 10/19/2022] [Indexed: 04/07/2024] Open
Abstract
Powered knee exoskeletons have shown potential for mobility restoration and power augmentation. However, the benefits of exoskeletons are partially offset by some design challenges that still limit their positive effects on people. Among them, joint misalignment is a critical aspect mostly because the human knee joint movement is not a fixed-axis rotation. In addition, remarkable mass and stiffness are also limitations. Aiming to minimize joint misalignment, this paper proposes a bio-inspired knee exoskeleton with a joint design that mimics the human knee joint. Moreover, to accomplish a lightweight and high compliance design, a high stiffness cable-tension amplification mechanism is leveraged. Simulation results indicate our design can reduce 49.3 and 71.9% maximum total misalignment for walking and deep squatting activities, respectively. Experiments indicate that the exoskeleton has high compliance (0.4 and 0.1 Nm backdrive torque under unpowered and zero-torque modes, respectively), high control bandwidth (44 Hz), and high control accuracy (1.1 Nm root mean square tracking error, corresponding to 7.3% of the peak torque). This work demonstrates performance improvement compared with state-of-the-art exoskeletons.
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Affiliation(s)
- Shuangyue Yu
- Lab of Biomechatronics and Intelligent Robotics, Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC, United States
| | - Tzu-Hao Huang
- Lab of Biomechatronics and Intelligent Robotics, Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC, United States
| | - Antonio Di Lallo
- Lab of Biomechatronics and Intelligent Robotics, Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC, United States
| | - Sainan Zhang
- Lab of Biomechatronics and Intelligent Robotics, Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC, United States
- Department of Mechanical Engineering, City College of New York, New York, NY, United States
| | - Tian Wang
- Lab of Biomechatronics and Intelligent Robotics, Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC, United States
| | - Qiushi Fu
- Mechanical and Aerospace Engineering, University of Central Florida, Orlando, FL, United States
- NeuroMechanical Systems Laboratory, Biionix (Bionic Materials, Implants & Interfaces) Cluster, University of Central Florida, Orlando, FL, United States
| | - Hao Su
- Lab of Biomechatronics and Intelligent Robotics, Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC, United States
- Joint North Carolina State University/The University of North Carolina Department of Biomedical Engineering, NC State University, Raleigh, NC, United States
- Joint North Carolina State University/The University of North Carolina Department of Biomedical Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
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12
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Zhang Q, Fragnito N, Bao X, Sharma N. A deep learning method to predict ankle joint moment during walking at different speeds with ultrasound imaging: A framework for assistive devices control. WEARABLE TECHNOLOGIES 2022; 3:e20. [PMID: 38486894 PMCID: PMC10936300 DOI: 10.1017/wtc.2022.18] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 07/14/2022] [Accepted: 08/06/2022] [Indexed: 03/17/2024]
Abstract
Robotic assistive or rehabilitative devices are promising aids for people with neurological disorders as they help regain normative functions for both upper and lower limbs. However, it remains challenging to accurately estimate human intent or residual efforts non-invasively when using these robotic devices. In this article, we propose a deep learning approach that uses a brightness mode, that is, B-mode, of ultrasound (US) imaging from skeletal muscles to predict the ankle joint net plantarflexion moment while walking. The designed structure of customized deep convolutional neural networks (CNNs) guarantees the convergence and robustness of the deep learning approach. We investigated the influence of the US imaging's region of interest (ROI) on the net plantarflexion moment prediction performance. We also compared the CNN-based moment prediction performance utilizing B-mode US and sEMG spectrum imaging with the same ROI size. Experimental results from eight young participants walking on a treadmill at multiple speeds verified an improved accuracy by using the proposed US imaging + deep learning approach for net joint moment prediction. With the same CNN structure, compared to the prediction performance by using sEMG spectrum imaging, US imaging significantly reduced the normalized prediction root mean square error by 37.55% ( < .001) and increased the prediction coefficient of determination by 20.13% ( < .001). The findings show that the US imaging + deep learning approach personalizes the assessment of human joint voluntary effort, which can be incorporated with assistive or rehabilitative devices to improve clinical performance based on the assist-as-needed control strategy.
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Affiliation(s)
- Qiang Zhang
- Joint Department of Biomedical Engineering, North Carolina State University, Raleigh, NC, USA
- Joint Department of Biomedical Engineering, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Natalie Fragnito
- Joint Department of Biomedical Engineering, North Carolina State University, Raleigh, NC, USA
- Joint Department of Biomedical Engineering, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Xuefeng Bao
- Biomedical Engineering Department, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Nitin Sharma
- Joint Department of Biomedical Engineering, North Carolina State University, Raleigh, NC, USA
- Joint Department of Biomedical Engineering, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
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13
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Liang J, Zhang Q, Liu Y, Wang T, Wan G. A review of the design of load-carrying exoskeletons. SCIENCE CHINA. TECHNOLOGICAL SCIENCES 2022; 65:2051-2067. [PMID: 36032505 PMCID: PMC9392988 DOI: 10.1007/s11431-022-2145-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Accepted: 07/07/2022] [Indexed: 06/15/2023]
Abstract
The increasing necessity of load-carrying activities has led to greater human musculoskeletal damage and an increased metabolic cost. With the rise of exoskeleton technology, researchers have begun exploring different approaches to developing wearable robots to augment human load-carrying ability. However, there is a lack of systematic discussion on biomechanics, mechanical designs, and augmentation performance. To achieve this, extensive studies have been reviewed and 108 references are selected mainly from 2013 to 2022 to address the most recent development. Other earlier 20 studies are selected to present the origin of different design principles. In terms of the way to achieve load-carrying augmentation, the exoskeletons reviewed in this paper are sorted by four categories based on the design principles, namely load-suspended backpacks, lower-limb exoskeletons providing joint torques, exoskeletons transferring load to the ground and exoskeletons transferring load between body segments. Specifically, the driving modes of active and passive, the structure of rigid and flexible, the conflict between assistive performance and the mass penalty of the exoskeleton, and the autonomy are discussed in detail in each section to illustrate the advances, challenges, and future trends of exoskeletons designed to carry loads.
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Affiliation(s)
- JieJunYi Liang
- State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan, 430074 China
| | - QinHao Zhang
- State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan, 430074 China
| | - Yang Liu
- State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan, 430074 China
| | - Tao Wang
- State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan, 430074 China
| | - GuangFu Wan
- State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan, 430074 China
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14
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Zhang Q, Fragnito N, Franz JR, Sharma N. Fused ultrasound and electromyography-driven neuromuscular model to improve plantarflexion moment prediction across walking speeds. J Neuroeng Rehabil 2022; 19:86. [PMID: 35945600 PMCID: PMC9361708 DOI: 10.1186/s12984-022-01061-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 07/21/2022] [Indexed: 11/28/2022] Open
Abstract
Background Improving the prediction ability of a human-machine interface (HMI) is critical to accomplish a bio-inspired or model-based control strategy for rehabilitation interventions, which are of increased interest to assist limb function post neurological injuries. A fundamental role of the HMI is to accurately predict human intent by mapping signals from a mechanical sensor or surface electromyography (sEMG) sensor. These sensors are limited to measuring the resulting limb force or movement or the neural signal evoking the force. As the intermediate mapping in the HMI also depends on muscle contractility, a motivation exists to include architectural features of the muscle as surrogates of dynamic muscle movement, thus further improving the HMI’s prediction accuracy. Objective The purpose of this study is to investigate a non-invasive sEMG and ultrasound (US) imaging-driven Hill-type neuromuscular model (HNM) for net ankle joint plantarflexion moment prediction. We hypothesize that the fusion of signals from sEMG and US imaging results in a more accurate net plantarflexion moment prediction than sole sEMG or US imaging. Methods Ten young non-disabled participants walked on a treadmill at speeds of 0.50, 0.75, 1.00, 1.25, and 1.50 m/s. The proposed HNM consists of two muscle-tendon units. The muscle activation for each unit was calculated as a weighted summation of the normalized sEMG signal and normalized muscle thickness signal from US imaging. The HNM calibration was performed under both single-speed mode and inter-speed mode, and then the calibrated HNM was validated across all walking speeds. Results On average, the normalized moment prediction root mean square error was reduced by 14.58 % (\documentclass[12pt]{minimal}
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\begin{document}$$p<0.001$$\end{document}p<0.001) with the proposed HNM when compared to sEMG-driven and US imaging-driven HNMs, respectively. Also, the calibrated models with data from the inter-speed mode were more robust than those from single-speed modes for the moment prediction. Conclusions The proposed sEMG-US imaging-driven HNM can significantly improve the net plantarflexion moment prediction accuracy across multiple walking speeds. The findings imply that the proposed HNM can be potentially used in bio-inspired control strategies for rehabilitative devices due to its superior prediction. Supplementary Information The online version contains supplementary material available at 10.1186/s12984-022-01061-z.
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Affiliation(s)
- Qiang Zhang
- Joint Department of Biomedical Engineering at the University of North Carolina-Chapel Hill and North Carolina State University, 1840 Entrepreneur Dr., 27695, Raleigh, NC, USA.,Joint Department of Biomedical Engineering at the University of North Carolina-Chapel Hill and North Carolina State University, 333 S Columbia St., 27514, Chapel Hill, NC, USA
| | - Natalie Fragnito
- Joint Department of Biomedical Engineering at the University of North Carolina-Chapel Hill and North Carolina State University, 1840 Entrepreneur Dr., 27695, Raleigh, NC, USA.,Joint Department of Biomedical Engineering at the University of North Carolina-Chapel Hill and North Carolina State University, 333 S Columbia St., 27514, Chapel Hill, NC, USA
| | - Jason R Franz
- Joint Department of Biomedical Engineering at the University of North Carolina-Chapel Hill and North Carolina State University, 1840 Entrepreneur Dr., 27695, Raleigh, NC, USA.,Joint Department of Biomedical Engineering at the University of North Carolina-Chapel Hill and North Carolina State University, 333 S Columbia St., 27514, Chapel Hill, NC, USA
| | - Nitin Sharma
- Joint Department of Biomedical Engineering at the University of North Carolina-Chapel Hill and North Carolina State University, 1840 Entrepreneur Dr., 27695, Raleigh, NC, USA. .,Joint Department of Biomedical Engineering at the University of North Carolina-Chapel Hill and North Carolina State University, 333 S Columbia St., 27514, Chapel Hill, NC, USA.
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15
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Massardi S, Rodriguez-Cianca D, Pinto-Fernandez D, Moreno JC, Lancini M, Torricelli D. Characterization and Evaluation of Human-Exoskeleton Interaction Dynamics: A Review. SENSORS (BASEL, SWITZERLAND) 2022; 22:3993. [PMID: 35684614 PMCID: PMC9183080 DOI: 10.3390/s22113993] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 05/21/2022] [Accepted: 05/23/2022] [Indexed: 02/01/2023]
Abstract
Exoskeletons and exosuits have witnessed unprecedented growth in recent years, especially in the medical and industrial sectors. In order to be successfully integrated into the current society, these devices must comply with several commercialization rules and safety standards. Due to their intrinsic coupling with human limbs, one of the main challenges is to test and prove the quality of physical interaction with humans. However, the study of physical human-exoskeleton interactions (pHEI) has been poorly addressed in the literature. Understanding and identifying the technological ways to assess pHEI is necessary for the future acceptance and large-scale use of these devices. The harmonization of these evaluation processes represents a key factor in building a still missing accepted framework to inform human-device contact safety. In this review, we identify, analyze, and discuss the metrics, testing procedures, and measurement devices used to assess pHEI in the last ten years. Furthermore, we discuss the role of pHEI in safety contact evaluation. We found a very heterogeneous panorama in terms of sensors and testing methods, which are still far from considering realistic conditions and use-cases. We identified the main gaps and drawbacks of current approaches, pointing towards a number of promising research directions. This review aspires to help the wearable robotics community find agreements on interaction quality and safety assessment testing procedures.
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Affiliation(s)
- Stefano Massardi
- Neural Rehabilitation Group, Cajal Institute, Spanish National Research Council (CSIC), 28006 Madrid, Spain; (S.M.); (D.R.-C.); (D.P.-F.); (J.C.M.)
- Department of Mechanical and Industrial Engineering (DIMI), University of Brescia, 25100 Brescia, Italy
| | - David Rodriguez-Cianca
- Neural Rehabilitation Group, Cajal Institute, Spanish National Research Council (CSIC), 28006 Madrid, Spain; (S.M.); (D.R.-C.); (D.P.-F.); (J.C.M.)
| | - David Pinto-Fernandez
- Neural Rehabilitation Group, Cajal Institute, Spanish National Research Council (CSIC), 28006 Madrid, Spain; (S.M.); (D.R.-C.); (D.P.-F.); (J.C.M.)
- Universidad Politécnica de Madrid (UPM), 28040 Madrid, Spain
| | - Juan C. Moreno
- Neural Rehabilitation Group, Cajal Institute, Spanish National Research Council (CSIC), 28006 Madrid, Spain; (S.M.); (D.R.-C.); (D.P.-F.); (J.C.M.)
| | - Matteo Lancini
- Department of Medical and Surgical Specialties, Radiological Sciences and Public Health (DSMC), University of Brescia, 25100 Brescia, Italy;
| | - Diego Torricelli
- Neural Rehabilitation Group, Cajal Institute, Spanish National Research Council (CSIC), 28006 Madrid, Spain; (S.M.); (D.R.-C.); (D.P.-F.); (J.C.M.)
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Development of a 3D Relative Motion Method for Human-Robot Interaction Assessment. SENSORS 2022; 22:s22062411. [PMID: 35336593 PMCID: PMC8952123 DOI: 10.3390/s22062411] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 03/10/2022] [Accepted: 03/11/2022] [Indexed: 12/10/2022]
Abstract
Exoskeletons have been assessed by qualitative and quantitative features known as performance indicators. Within these, the ergonomic indicators have been isolated, creating a lack of methodologies to analyze and assess physical interfaces. In this sense, this work presents a three-dimensional relative motion assessment method. This method quantifies the difference of orientation between the user’s limb and the exoskeleton link, providing a deeper understanding of the Human–Robot interaction. To this end, the AGoRA exoskeleton was configured in a resistive mode and assessed using an optoelectronic system. The interaction quantified a difference of orientation considerably at a maximum value of 41.1 degrees along the sagittal plane. It extended the understanding of the Human–Robot Interaction throughout the three principal human planes. Furthermore, the proposed method establishes a performance indicator of the physical interfaces of an exoskeleton.
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17
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Kim JY, Cho JS, Kim JH, Kim JT, Han SC, Park SS, Yoon HU. Spine-like Joint Link Mechanism to Design Wearable Assistive Devices. SENSORS 2022; 22:s22062314. [PMID: 35336489 PMCID: PMC8951149 DOI: 10.3390/s22062314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Revised: 03/09/2022] [Accepted: 03/14/2022] [Indexed: 11/16/2022]
Abstract
When we develop wearable assistive devices, comfort and support are two main issues that need to be considered. In conventional design approaches, the degree of freedom of the wearer’s joint movements tends to be oversimplified. Accordingly, the wearer’s motion becomes restrained and bone/ligament injuries might occur in case of an unexpected fall. To mitigate these issues, this paper proposes a novel joint link mechanism inspired by a human spine structure as well as functionalities. The key feature of the proposed spine-like joint link mechanism is that hemispherical blocks are concatenated via flexible synthetic fiber lines so that their concatenation stiffness can be adjusted according to a tensile force. This feature has a great potentiality for designing a wearable assistive device that can support aged people’s sit-to-stand action or augment spinal motion by regulating the concatenation stiffness. In addition, the concatenated hemispherical blocks enable the wearer to move his/her joint with full freedom, which in turn increases the wearer’s mobility and prevents joint misalignment. The experimental results with a testbed and a pilot wearer substantiated that the spine-like joint link mechanism can serve as a key component in the design of wearable assistive devices for better mobility.
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Affiliation(s)
- Jung-Yeong Kim
- Robotics, University of Science and Technology (UST), Daejon 34113, Korea; (J.-Y.K.); (J.-S.C.)
- Robotics R&D Department, Korea Institute of Industrial Technology (KITECH), Ansan 15588, Korea; (J.-H.K.); (J.-T.K.); (S.-C.H.); (S.-S.P.)
| | - Jung-San Cho
- Robotics, University of Science and Technology (UST), Daejon 34113, Korea; (J.-Y.K.); (J.-S.C.)
- Robotics R&D Department, Korea Institute of Industrial Technology (KITECH), Ansan 15588, Korea; (J.-H.K.); (J.-T.K.); (S.-C.H.); (S.-S.P.)
| | - Jin-Hyeon Kim
- Robotics R&D Department, Korea Institute of Industrial Technology (KITECH), Ansan 15588, Korea; (J.-H.K.); (J.-T.K.); (S.-C.H.); (S.-S.P.)
| | - Jin-Tak Kim
- Robotics R&D Department, Korea Institute of Industrial Technology (KITECH), Ansan 15588, Korea; (J.-H.K.); (J.-T.K.); (S.-C.H.); (S.-S.P.)
| | - Sang-Chul Han
- Robotics R&D Department, Korea Institute of Industrial Technology (KITECH), Ansan 15588, Korea; (J.-H.K.); (J.-T.K.); (S.-C.H.); (S.-S.P.)
| | - Sang-Shin Park
- Robotics R&D Department, Korea Institute of Industrial Technology (KITECH), Ansan 15588, Korea; (J.-H.K.); (J.-T.K.); (S.-C.H.); (S.-S.P.)
| | - Han-Ul Yoon
- Division of Software, Yonsei University, Wonju 26493, Korea
- Correspondence: ; Tel.: +82-33-760-2235
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Hong JC, Ohashi H, Iwata H. High-Dorsiflexion Assistive System for Passive Swing Phase Dorsiflexion Training and Preventing Compensatory Movements. JOURNAL OF ROBOTICS AND MECHATRONICS 2022. [DOI: 10.20965/jrm.2022.p0121] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Over the last few years, numerous robotic ankle-foot orthoses have been developed to help stroke patients optimize gait rehabilitation. In this paper, we present a study on the effects of assistance on dorsiflexion-restricted gait. Our high-dorsiflexion assistive system aims to provide full assistance to realize passive training of dorsiflexion during the swing phase and prevent compensatory movements. This system, which includes a McKibben-type artificial muscle and an air source, is lightweight and provides a high-dorsiflexion torque. The device could help boost overground gait rehabilitation in stroke patients. With this system, we conducted an experiment on five healthy participants whose dorsiflexion movements were restricted, and the extent of their compensatory movements differed. The results of the processed surface electromyography data differed significantly when dorsiflexion movement was assisted by our system. The spatial parameters also showed significantly improved compensatory movement inclination with sufficient assistance. These results indicate the potential of our system to assist in passive training of ankle dorsiflexion movements and to prevent incorrect gait in patients with low dorsiflexion abilities.
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19
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Bessler-Etten J, Schaake L, Prange-Lasonder GB, Buurke JH. Assessing effects of exoskeleton misalignment on knee joint load during swing using an instrumented leg simulator. J Neuroeng Rehabil 2022; 19:13. [PMID: 35090501 PMCID: PMC8800279 DOI: 10.1186/s12984-022-00990-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Accepted: 01/14/2022] [Indexed: 12/04/2022] Open
Abstract
Background Exoskeletons are working in parallel to the human body and can support human movement by exerting forces through cuffs or straps. They are prone to misalignments caused by simplified joint mechanics and incorrect fit or positioning. Those misalignments are a common safety concern as they can cause undesired interaction forces. However, the exact mechanisms and effects of misalignments on the joint load are not yet known. The aim of this study was therefore to investigate the influence of different directions and magnitudes of exoskeleton misalignment on the internal knee joint forces and torques of an artificial leg.
Methods An instrumented leg simulator was used to quantify the changes in knee joint load during the swing phase caused by misalignments of a passive knee brace being manually flexed. This was achieved by an experimenter pulling on a rope attached to the distal end of the knee brace to create a flexion torque. The extension was not actuated but achieved through the weight of the instrumented leg simulator. The investigated types of misalignments are a rotation of the brace around the vertical axis and a translation in anteroposterior as well as proximal/distal direction. Results The amount of misalignment had a significant effect on several directions of knee joint load in the instrumented leg simulator. In general, load on the knee joint increased with increasing misalignment. Specifically, stronger rotational misalignment led to higher forces in mediolateral direction in the knee joint as well as higher ab-/adduction, flexion and internal/external rotation torques. Stronger anteroposterior translational misalignment led to higher mediolateral knee forces as well as higher abduction and flexion/extension torques. Stronger proximal/distal translational misalignment led to higher posterior and tension/compression forces. Conclusions Misalignments of a lower leg exoskeleton can increase internal knee forces and torques during swing to a multiple of those experienced in a well-aligned situation. Despite only taking swing into account, this is supporting the need for carefully considering hazards associated with not only translational but also rotational misalignments during wearable robot development and use. Also, this warrants investigation of misalignment effects in stance, as a target of many exoskeleton applications.
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20
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Personalized fusion of ultrasound and electromyography-derived neuromuscular features increases prediction accuracy of ankle moment during plantarflexion. Biomed Signal Process Control 2022. [DOI: 10.1016/j.bspc.2021.103100] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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21
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Huang TH, Zhang S, Yu S, MacLean MK, Zhu J, Di Lallo A, Jiao C, Bulea TC, Zheng M, Su H. Modeling and Stiffness-Based Continuous Torque Control of Lightweight Quasi-Direct-Drive Knee Exoskeletons for Versatile Walking Assistance. IEEE T ROBOT 2022; 38:1442-1459. [DOI: 10.1109/tro.2022.3170287] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Tzu-Hao Huang
- Laboratory of Biomechatronics and Intelligent Robotics, Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC 27695 USA
| | - Sainan Zhang
- Laboratory of Biomechatronics and Intelligent Robotics, Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC 27695 USA
| | - Shuangyue Yu
- Laboratory of Biomechatronics and Intelligent Robotics, Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC 27695 USA
| | - Mhairi K. MacLean
- Laboratory of Biomechatronics and Intelligent Robotics 57522, Enschede The Netherlands, and also with the Department of Mechanical Engineering, University of Twente 57522, Enschede The Netherlands
| | - Junxi Zhu
- Laboratory of Biomechatronics and Intelligent Robotics, Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC 27695 USA
| | - Antonio Di Lallo
- Laboratory of Biomechatronics and Intelligent Robotics, Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC 27695 USA
| | - Chunhai Jiao
- Laboratory of Biomechatronics and Intelligent Robotics, Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC 27695 USA
| | - Thomas C. Bulea
- Functional and Applied Biomechanics Section, Rehabilitation Medicine Department, Clinical Center, National Institutes of Health, Bethesda, MD 20892 USA
| | - Minghui Zheng
- Department of Mechanical and Aerospace Engineering, University at Buffalo, Buffalo, NY 14260 USA
| | - Hao Su
- Laboratory of Biomechatronics and Intelligent Robotics, Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC 27695 USA
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Sarajchi M, Al-Hares MK, Sirlantzis K. Wearable Lower-Limb Exoskeleton for Children With Cerebral Palsy: A Systematic Review of Mechanical Design, Actuation Type, Control Strategy, and Clinical Evaluation. IEEE Trans Neural Syst Rehabil Eng 2021; 29:2695-2720. [PMID: 34910636 DOI: 10.1109/tnsre.2021.3136088] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Children with a neurological disorder such as cerebral palsy (CP) severely suffer from a reduced quality of life because of decreasing independence and mobility. Although there is no cure yet, a lower-limb exoskeleton (LLE) has considerable potential to help these children experience better mobility during overground walking. The research in wearable exoskeletons for children with CP is still at an early stage. This paper shows that the number of published papers on LLEs assisting children with CP has significantly increased in recent years; however, no research has been carried out to review these studies systematically. To fill up this research gap, a systematic review from a technical and clinical perspective has been conducted, based on the PRISMA guidelines, under three extended topics associated with "lower limb", "exoskeleton", and "cerebral palsy" in the databases Scopus and Web of Science. After applying several exclusion criteria, seventeen articles focused on fifteen LLEs were included for careful consideration. These studies address some consistent positive evidence on the efficacy of LLEs in improving gait patterns in children with CP. Statistical findings show that knee exoskeletons, brushless DC motors, the hierarchy control architecture, and CP children with spastic diplegia are, respectively, the most common mechanical design, actuator type, control strategy, and clinical characteristics for these LLEs. Clinical studies suggest ankle-foot orthosis as the primary medical solution for most CP gait patterns; nevertheless, only one motorized ankle exoskeleton has been developed. This paper shows that more research and contribution are needed to deal with open challenges in these LLEs.
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Sanjeevi N, Singh Y, Vashista V. Recent advances in lower-extremity exoskeletons in promoting performance restoration. CURRENT OPINION IN BIOMEDICAL ENGINEERING 2021. [DOI: 10.1016/j.cobme.2021.100338] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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Zhang Q, Fragnito N, Myers A, Sharma N. Plantarflexion Moment Prediction during the Walking Stance Phase with an sEMG-Ultrasound Imaging-Driven Model. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2021; 2021:6267-6272. [PMID: 34892546 DOI: 10.1109/embc46164.2021.9630046] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Many rehabilitative exoskeletons use non-invasive surface electromyography (sEMG) to measure human volitional intent. However, signals from adjacent muscle groups interfere with sEMG measurements. Further, the inability to measure sEMG signals from deeply located muscles may not accurately measure the volitional intent. In this work, we combined sEMG and ultrasound (US) imaging-derived signals to improve the prediction accuracy of voluntary ankle effort. We used a multivariate linear model (MLM) that combines sEMG and US signals for ankle joint net plantarflexion (PF) moment prediction during the walking stance phase. We hypothesized that the proposed sEMG-US imaging-driven MLM would result in more accurate net PF moment prediction than sEMG-driven and US imaging-driven MLMs. Synchronous measurements including reflective makers coordinates, ground reaction forces, sEMG signals of lateral/medial gastrocnemius (LGS/MGS), and soleus (SOL) muscles, and US imaging of LGS and SOL muscles were collected from five able-bodied participants walking on a treadmill at multiple speeds. The ankle joint net PF moment benchmark was calculated based on inverse dynamics, while the net PF moment prediction was determined by the sEMG-US imaging-driven, sEMG-driven, and US imaging-driven MLMs. The findings show that the sEMG-US imaging-driven MLM can significantly improve the prediction of net PF moment during the walking stance phase at multiple speeds. Potentially, the proposed sEMG-US imaging-driven MLM can be used as a superior joint motion intent model in advanced and intelligent control strategies for rehabilitative exoskeletons.
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Knee Exoskeletons Design Approaches to Boost Strength Capability: A Review. APPLIED SCIENCES-BASEL 2021. [DOI: 10.3390/app11219990] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
There are different devices to increase the strength capacity of people with walking problems. These devices can be classified into exoskeletons, orthotics, and braces. This review aims to identify the state of the art in the design of these medical devices, based on an analysis of patents and literature. However, there are some difficulties in processing the records due to the lack of filters and standardization in the names, generating discrepancies between the search engines, among others. Concerning the patents, 74 patents were analyzed using search engines such as Google Patents, Derwent, The Lens, Patentscope, and Espacenet over the past ten years. A bibliometric analysis was performed using 63 scientific reports from Web of Science and The Lens in the same period for scientific communications. The results show a trend to use the mechanical design of exoskeletons based on articulated rigid structures and elements that provide force to move the structure. These are generally two types: (a) elastic elements and (b) electromechanical elements. The United States accounts for 32% of the technological patents reviewed. The results suggest that the use of exoskeletons or orthoses customized to the users’ needs will continue to increase over the years due to the worldwide growth in disability, particularly related to mobility difficulties and technologies related to the combined use of springs and actuators.
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Thomas GC, Campbell O, Nichols N, Brissonneau N, He B, James J, Paine N, Sentis L. Formulating and Deploying Strength Amplification Controllers for Lower-Body Walking Exoskeletons. Front Robot AI 2021; 8:720231. [PMID: 34646867 PMCID: PMC8502972 DOI: 10.3389/frobt.2021.720231] [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: 06/03/2021] [Accepted: 08/30/2021] [Indexed: 11/18/2022] Open
Abstract
Augmenting the physical strength of a human operator during unpredictable human-directed (volitional) movements is a relevant capability for several proposed exoskeleton applications, including mobility augmentation, manual material handling, and tool operation. Unlike controllers and augmentation systems designed for repetitive tasks (e.g., walking), we approach physical strength augmentation by a task-agnostic method of force amplification—using force/torque sensors at the human–machine interface to estimate the human task force, and then amplifying it with the exoskeleton. We deploy an amplification controller that is integrated into a complete whole-body control framework for controlling exoskeletons that includes human-led foot transitions, inequality constraints, and a computationally efficient prioritization. A powered lower-body exoskeleton is used to demonstrate behavior of the control framework in a lab environment. This exoskeleton can assist the operator in lifting an unknown backpack payload while remaining fully backdrivable.
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Affiliation(s)
- Gray C Thomas
- Department of Electrical Engineering and Computer Science, The University of Michigan, Ann Arbor, MI, United States
| | | | | | - Nicolas Brissonneau
- The Human Centered Robotics Lab, The University of Texas at Austin, Austin, TX, United States
| | - Binghan He
- The Human Centered Robotics Lab, The University of Texas at Austin, Austin, TX, United States
| | | | | | - Luis Sentis
- The Human Centered Robotics Lab, The University of Texas at Austin, Austin, TX, United States
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Bacek T, Moltedo M, Serrien B, Langlois K, Vanderborght B, Lefeber D, Rodriguez-Guerrero C. Human Musculoskeletal and Energetic Adaptations to Unilateral Robotic Knee Gait Assistance. IEEE Trans Biomed Eng 2021; 69:1141-1150. [PMID: 34559629 DOI: 10.1109/tbme.2021.3114737] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE This paper aims to analyse the human musculoskeletal and energetic adaptation mechanisms when physically interacting with a unilateral knee orthosis during treadmill walking. METHODS Test subjects participated in two walking trials, whereby the orthosis was controlled to deliver five predefined torque profiles of different duration (as % of a gait cycle). The adaptations to assistive torques of different duration were analysed in terms of gait parameters, metabolic effort, and muscle activity. RESULTS Orthotic assistances kinematic effects remain local to the assisted leg and joint, unlike the muscles spanning the knee joint, which engage in a balancing-out action to retain stability. Duration of assistive torque significantly affects only the timing of the knee joints peak flexion angle in the stance phase, while the observed joint kinematics and muscle activity demonstrate different recovery times upon changing robotic support (washout effects). CONCLUSION Human body adaptations to external robotic knee joint assistance during walking take place on multiple levels and to a different extent in a joint effort to keep the gait stable. SIGNIFICANCE This paper provides important insights into the human bodys multiple adaptation mechanisms in the presence of external robotic assistance.
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Zhang Q, Iyer A, Sun Z, Kim K, Sharma N. A Dual-Modal Approach Using Electromyography and Sonomyography Improves Prediction of Dynamic Ankle Movement: A Case Study. IEEE Trans Neural Syst Rehabil Eng 2021; 29:1944-1954. [PMID: 34428143 DOI: 10.1109/tnsre.2021.3106900] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
For decades, surface electromyography (sEMG) has been a popular non-invasive bio-sensing technology for predicting human joint motion. However, cross-talk, interference from adjacent muscles, and its inability to measure deeply located muscles limit its performance in predicting joint motion. Recently, ultrasound (US) imaging has been proposed as an alternative non-invasive technology to predict joint movement due to its high signal-to-noise ratio, direct visualization of targeted tissue, and ability to access deep-seated muscles. This paper proposes a dual-modal approach that combines US imaging and sEMG for predicting volitional dynamic ankle dorsiflexion movement. Three feature sets: 1) a uni-modal set with four sEMG features, 2) a uni-modal set with four US imaging features, and 3) a dual-modal set with four dominant sEMG and US imaging features, together with measured ankle dorsiflexion angles, were used to train multiple machine learning regression models. The experimental results from a seated posture and five walking trials at different speeds, ranging from 0.50 m/s to 1.50 m/s, showed that the dual-modal set significantly reduced the prediction root mean square errors (RMSEs). Compared to the uni-modal sEMG feature set, the dual-modal set reduced RMSEs by up to 47.84% for the seated posture and up to 77.72% for the walking trials. Similarly, when compared to the US imaging feature set, the dual-modal set reduced RMSEs by up to 53.95% for the seated posture and up to 58.39% for the walking trials. The findings show that potentially the dual-modal sensing approach can be used as a superior sensing modality to predict human intent of a continuous motion and implemented for volitional control of clinical rehabilitative and assistive devices.
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Russell F, Takeda Y, Kormushev P, Vaidyanathan R, Ellison P. Stiffness Modulation in a Humanoid Robotic Leg and Knee. IEEE Robot Autom Lett 2021. [DOI: 10.1109/lra.2021.3062355] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Bessler J, Prange-Lasonder GB, Schaake L, Saenz JF, Bidard C, Fassi I, Valori M, Lassen AB, Buurke JH. Safety Assessment of Rehabilitation Robots: A Review Identifying Safety Skills and Current Knowledge Gaps. Front Robot AI 2021; 8:602878. [PMID: 33937345 PMCID: PMC8080797 DOI: 10.3389/frobt.2021.602878] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 01/28/2021] [Indexed: 11/19/2022] Open
Abstract
The assessment of rehabilitation robot safety is a vital aspect of the development process, which is often experienced as difficult. There are gaps in best practices and knowledge to ensure safe usage of rehabilitation robots. Currently, safety is commonly assessed by monitoring adverse events occurrence. The aim of this article is to explore how safety of rehabilitation robots can be assessed early in the development phase, before they are used with patients. We are suggesting a uniform approach for safety validation of robots closely interacting with humans, based on safety skills and validation protocols. Safety skills are an abstract representation of the ability of a robot to reduce a specific risk or deal with a specific hazard. They can be implemented in various ways, depending on the application requirements, which enables the use of a single safety skill across a wide range of applications and domains. Safety validation protocols have been developed that correspond to these skills and consider domain-specific conditions. This gives robot users and developers concise testing procedures to prove the mechanical safety of their robotic system, even when the applications are in domains with a lack of standards and best practices such as the healthcare domain. Based on knowledge about adverse events occurring in rehabilitation robot use, we identified multi-directional excessive forces on the soft tissue level and musculoskeletal level as most relevant hazards for rehabilitation robots and related them to four safety skills, providing a concrete starting point for safety assessment of rehabilitation robots. We further identified a number of gaps which need to be addressed in the future to pave the way for more comprehensive guidelines for rehabilitation robot safety assessments. Predominantly, besides new developments of safety by design features, there is a strong need for reliable measurement methods as well as acceptable limit values for human-robot interaction forces both on skin and joint level.
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Affiliation(s)
- Jule Bessler
- Roessingh Research and Development, Enschede, Netherlands.,Department of Biomedical Signals and Systems, University of Twente, Enschede, Netherlands
| | - Gerdienke B Prange-Lasonder
- Roessingh Research and Development, Enschede, Netherlands.,Department of Biomechanical Engineering, University of Twente, Enschede, Netherlands
| | | | - José F Saenz
- Fraunhofer Institute for Factory Operation and Automation, Magdeburg, Germany
| | | | - Irene Fassi
- National Research Council of Italy, Milan, Italy
| | | | - Aske Bach Lassen
- Department of Robot Technology, Danish Technological Institute, Odense, Denmark
| | - Jaap H Buurke
- Roessingh Research and Development, Enschede, Netherlands.,Department of Biomedical Signals and Systems, University of Twente, Enschede, Netherlands
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Sarkisian SV, Ishmael MK, Lenzi T. Self-Aligning Mechanism Improves Comfort and Performance With a Powered Knee Exoskeleton. IEEE Trans Neural Syst Rehabil Eng 2021; 29:629-640. [PMID: 33684041 DOI: 10.1109/tnsre.2021.3064463] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Misalignments between powered exoskeleton joints and the user's anatomical joints are inevitable due to difficulty locating the anatomical joint axis, non-constant location of the anatomical joint axis, and soft-tissue deformations. Self-aligning mechanisms have been proposed to prevent spurious forces and torques on the user's limb due to misalignments. Several exoskeletons have been developed with self-aligning mechanisms based on theoretical models. However, there is no experimental evidence demonstrating the efficacy of self-aligning mechanisms in lower-limb exoskeletons. Here we show that a lightweight and compact self-aligning mechanism improves the user's comfort and performance while using a powered knee exoskeleton. Experiments were conducted with 14 able-bodied subjects with the self-aligning mechanism locked and unlocked. Our results demonstrate up to 15.3% increased comfort and 38% improved performance when the self-aligning mechanism was unlocked. Not surprisingly, the spurious forces and torques were reduced by up to 97% when the self-aligning mechanism was unlocked. This study demonstrates the efficacy of self-aligning mechanisms in improving comfort and performance for sit-to-stand and position tracking tasks with a powered knee exoskeleton.
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McGrath R, Bodt B, Sergi F. Robot-Aided Training of Propulsion During Walking: Effects of Torque Pulses Applied to the Hip and Knee Joints During Stance. IEEE Trans Neural Syst Rehabil Eng 2020; 28:2923-2932. [PMID: 33232239 DOI: 10.1109/tnsre.2020.3039962] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
We sought to evaluate the effects of the application of torque pulses to the hip and knee joint via a robotic exoskeleton in the context of training propulsion during walking. Based on our previous study, we formulated a set of conditions of torque pulses applied to the hip and knee joint associated with changes in push-off posture, a component of propulsion. In this work, we quantified the effects of hip/knee torque pulses on metrics of propulsion, specifically hip extension (HE) and normalized propulsive impulse (NPI), in two experiments. In the first experiment, we exposed 16 participants to sixteen conditions of torque pulses during single strides to observe the immediate effects of pulse application. In the second experiment, we exposed 16 participants to a subset of those conditions for 200 strides to quantify short-term adaptation effects. During pulse application, NPI aligned with the expected modulation of push-off posture, while HE was modulated in the opposite direction. The timing of the applied pulses, early or late stance, was crucial, as the effects were often in the opposite direction when changing timing condition. Extension torque applied at late stance increased HE in both experiments - range of change in HE: (2.9 ± 0.4 deg, 7.7 ± 1.0 deg), . The same conditions resulted in a negative change in NPI only in the single pulse experiment - change in NPI for knee torque: -3.0 ± 0.4 ms, - and no significant change for hip torque. Also, knee extension and flexion torque during early and late stance, respectively, increased NPI during single pulse application - range of change in NPI: (3.8, 4.6) ± 0.8 ms, . During repeated pulse application, NPI increased for late stance flexion torque - range of change in NPI: (4.5 ± 0.7 ms, 4.8 ± 0.8 ms), , but not late stance extension torque. After exposure, we observed positive after-effects in HE in three conditions - range of change in HE: (2.0 ± 0.3 deg, 3.7 ± 0.7 deg) - and significant positive after-effects in NPI for early stance flexion torques - change in NPI: (2.7 ± 0.6 ms, ). These results indicate that positive propulsive after-effects can be achieved through repeated exposure to torque pulses.
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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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Lee H, Kim SH, Park HS. A Fully Soft and Passive Assistive Device to Lower the Metabolic Cost of Sit-to-Stand. Front Bioeng Biotechnol 2020; 8:966. [PMID: 32923435 PMCID: PMC7456876 DOI: 10.3389/fbioe.2020.00966] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 07/27/2020] [Indexed: 11/13/2022] Open
Abstract
Various assistive devices like exoskeletons have been developed to aid the growing number of disabled people. Recent studies have started to explore using soft rather than rigid components to create lightweight and unobtrusive systems that can be more easily adopted by the general population. However, there is a tradeoff between compliance and power in these systems. We investigated the physiological benefits of using an inconspicuous, soft and passive assistive device which would avoid bulkiness, heaviness and user discomfort. We chose to assist the sit-to-stand (STS) maneuver because it is a common activity of daily living (ADL). STS is also recognized as one of the most challenging ADLs due to the high knee torque required, and the primary limiting factor is known to be knee extensor strength. Thus, the objective of this research was to develop and evaluate an unobtrusive knee assist wear called X-tights that could aid knee extension during STS using only soft and passive components. This was accomplished by routing elastic bands across the lower extremity. Thirty-one healthy participants performed STS tests with and without the X-tights, while metabolic cost and muscle activity were recorded. Metabolic power significantly decreased, by 3.2 ± 1.5% (P = 0.04), when utilizing the X-tights during the STS, while there was no statistically significant differences in muscle activity. The present work introduces a new soft and passive assist wear that can be worn inconspicuously under normal clothing, and we demonstrate promising results for the future development and integration of soft assistive technology for daily life.
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Affiliation(s)
- Hangil Lee
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, South Korea
| | - Seok Hee Kim
- Exercise Physiology, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, South Korea
| | - Hyung-Soon Park
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, South Korea
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Zhang Q, Iyer A, Kim K, Sharma N. Evaluation of Non-Invasive Ankle Joint Effort Prediction Methods for Use in Neurorehabilitation Using Electromyography and Ultrasound Imaging. IEEE Trans Biomed Eng 2020; 68:1044-1055. [PMID: 32759078 DOI: 10.1109/tbme.2020.3014861] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVE Reliable measurement of voluntary human effort is essential for effective and safe interaction between the wearer and an assistive robot. Existing voluntary effort prediction methods that use surface electromyography (sEMG) are susceptible to prediction inaccuracies due to non-selectivity in measuring muscle responses. This technical challenge motivates an investigation into alternative non-invasive effort prediction methods that directly visualize the muscle response and improve effort prediction accuracy. The paper is a comparative study of ultrasound imaging (US)-derived neuromuscular signals and sEMG signals for their use in predicting isometric ankle dorsiflexion moment. Furthermore, the study evaluates the prediction accuracy of model-based and model-free voluntary effort prediction approaches that use these signals. METHODS The study evaluates sEMG signals and three US imaging-derived signals: pennation angle, muscle fascicle length, and echogenicity and three voluntary effort prediction methods: linear regression (LR), feedforward neural network (FFNN), and Hill-type neuromuscular model (HNM). RESULTS In all the prediction methods, pennation angle and fascicle length significantly improve the prediction accuracy of dorsiflexion moment, when compared to echogenicity. Also, compared to LR, both FFNN and HNM improve dorsiflexion moment prediction accuracy. CONCLUSION The findings indicate FFNN or HNM approach and using pennation angle or fascicle length predict human ankle movement intent with higher accuracy. SIGNIFICANCE The accurate ankle effort prediction will pave the path to safe and reliable robotic assistance in patients with drop foot.
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Knee-Assistive Robotic Exoskeleton (KARE-1) Using a Conditionally Singular Mechanism for Industrial Field Applications. APPLIED SCIENCES-BASEL 2020. [DOI: 10.3390/app10155141] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
With the aging demographic of today’s society, the need for robotic exoskeletons is expected to increase as they can compensate for declining physical strength in the physically impaired. In this study, an assistive robotic exoskeleton for the knee joint with fairly low energy consumption is proposed for industrial applications. The knee-assistive robotic exoskeleton (KARE-1) was designed to support a human body during production line tasks. The KARE-1 is based on a four-bar link mechanism with a rotary actuator and gas spring to accommodate a high power-to-weight ratio. By taking advantage of the utilized singular configuration of the four-bar linkage, this novel design is able to efficiently support the weight of the human body. The selected singular configuration allows this device to support the knee joint in the load-bearing stages of static sitting as well as during the motion between standing and sitting. The proposed device is further able to move freely along with the knee during walking movements. The proposed design was verified through a series of numerical simulations and through human subject testing at an industrial workplace.
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37
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Hidayah R, Bishop L, Jin X, Chamarthy S, Stein J, Agrawal SK. Gait Adaptation Using a Cable-Driven Active Leg Exoskeleton (C-ALEX) With Post-Stroke Participants. IEEE Trans Neural Syst Rehabil Eng 2020; 28:1984-1993. [PMID: 32746320 DOI: 10.1109/tnsre.2020.3009317] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Individuals with chronic hemiparesis post-stroke exhibit gait impairments that require functional rehabilitation through training. Exoskeletal robotic assistive devices can provide a user with continuous assistance but impose movement restrictions. There are currently devices that allow unrestricted movement but provide assistance only intermittently at specific points of the gait cycle. Our design, a cable-driven active leg exoskeleton (C-ALEX), allows the user both unrestricted movement and continuous force assistance throughout the gait cycle to assist the user in new walking patterns. In this study, we assessed the ability of C-ALEX to induce a change in the walking patterns of ten post-stroke participants using a single-session training protocol. The ability of C-ALEX to accurately provide forces and torques in the desired directions was also evaluated to compare its design performance to traditional rigid-link designs. Participants were able to reach 91% ± 12% of their target step length and 89% ± 13% of their target step height. The achieved step parameters differed significantly from participant baselines ( ). To quantify the performance, the forces in each cable's out of the plane movements were evaluated relative to the in-plane desired cable tension magnitudes. This corresponded to an error of under 2Nm in the desired controlled joint torques. This error magnitude is low compared to the system command torques and typical adult biological torques during walking (2-4%). These results point to the utility of using non-restrictive cable-driven architectures in gait retraining, in which future focus can be on rehabilitating gait pathologies seen in stroke survivors.
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Park EJ, Akbas T, Eckert-Erdheim A, Sloot LH, Nuckols RW, Orzel D, Schumm L, Ellis TD, Awad LN, Walsh CJ. A hinge-free, non-restrictive, lightweight tethered exosuit for knee extension assistance during walking. ACTA ACUST UNITED AC 2020; 2:165-175. [PMID: 33748694 DOI: 10.1109/tmrb.2020.2989321] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
In individuals with motor impairments such as those post-stroke or with cerebral palsy, the function of the knee extensors may be affected during walking, resulting in decreased mobility. We have designed a lightweight, hinge-free wearable robot combining soft textile exosuit components with integrated rigid components, which assists knee extension when needed but is otherwise highly transparent to the wearer. The exosuit can apply a wide range of assistance profiles using a flexible multi-point reference trajectory generator. Additionally, we implemented a controller safety limit to address the risk of hyperextension stemming from the hinge-free design. The exosuit was evaluated on six healthy participants walking uphill and downhill on a treadmill at a 10° slope with a set of joint power-inspired assistance profiles. A comparison of sagittal plane joint angles between no exosuit and exosuit unpowered conditions validated the device transparency. With positive power assistance, we observed reduction in average positive knee biological power during uphill walking (left: 17.5 ± 3.21%, p = 0.005; right: 23.2 ± 3.54%, p = 0.008). These initial findings show promise for the assistive capability of the device and its potential to improve the quality of gait and increase mobility in clinical populations.
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Affiliation(s)
- Evelyn J Park
- School of Engineering and Applied Sciences and the Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138 USA
| | - Tunc Akbas
- School of Engineering and Applied Sciences and the Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138 USA
| | - Asa Eckert-Erdheim
- School of Engineering and Applied Sciences and the Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138 USA
| | - Lizeth H Sloot
- Institute for Computer Engineering (ZITI) at Heidelberg University, Heidelberg, Germany
| | - Richard W Nuckols
- School of Engineering and Applied Sciences and the Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138 USA
| | - Dorothy Orzel
- School of Engineering and Applied Sciences and the Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138 USA
| | - Lexine Schumm
- School of Engineering and Applied Sciences and the Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138 USA
| | - Terry D Ellis
- Department of Physical Therapy & Athletic Training, Sargent College, Boston University, Boston, MA 02215 USA
| | - Louis N Awad
- Department of Physical Therapy & Athletic Training, Sargent College, Boston University, Boston, MA 02215 USA
| | - Conor J Walsh
- School of Engineering and Applied Sciences and the Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138 USA
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Wan X, Liu Y, Akiyama Y, Yamada Y. Monitoring Contact Behavior During Assisted Walking With a Lower Limb Exoskeleton. IEEE Trans Neural Syst Rehabil Eng 2020; 28:869-877. [PMID: 32167901 DOI: 10.1109/tnsre.2020.2979986] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Interaction forces between a robotic cuff and the skin during assisted walking with a lower limb exoskeleton may cause skin injuries over time, such as blisters and ulcers. This study proposes a sensing cuff that can monitor the contact behavior between the exoskeleton and skin during assisted walking, and a functional test and assisted walking experiments were conducted to evaluate the performance of the proposed device. The functional test of the sensing cuff showed good performance of capturing the contact behavior for safety evaluation. The walking experiment involved subjects walking on a treadmill with a lower limb exoskeleton under different conditions (i.e., walking speed and clothing), and the sensing cuff attached to the exoskeleton measured the interaction forces and slip velocity. The magnitude of shear force in the movement direction peaked near the beginning and within 40 - 50% of the gait cycle. The contact safety of the lower limb exoskeleton during assisted walking was then evaluated based on the calculated shear stress. The designed sensing cuff could provide sufficient information regarding contact behavior and contact safety during assisted walking.
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Akiyama Y, Fukui Y, Okamoto S, Yamada Y. Effects of exoskeletal gait assistance on the recovery motion following tripping. PLoS One 2020; 15:e0229150. [PMID: 32092091 PMCID: PMC7039667 DOI: 10.1371/journal.pone.0229150] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Accepted: 01/30/2020] [Indexed: 11/30/2022] Open
Abstract
Physical assistant robots improve the user’s ability to walk. However, they also potentially affect recovery motion following tripping. The assist algorithm should not interfere with the recovery motion, and should enhance the ability of the user to recover after tripping. Thus, in this study, we investigated the recovery motion affected by the assist robot after tripping. We compared the recovery motion with different reaction algorithms. Principal component analysis revealed the effects of the reaction algorithm. Correspondingly, principal components were related to the recovery motion during two steps following tripping. Specifically, the effects of the reaction algorithm were related to a principal component that represented the motion of the second step after tripping and that increased the margin of stability. Furthermore, the margin of stability became significantly large when the assistive torque was applied during the recovery motion. The result of this study suggests that the assist robot can potentially enhances the recovery motion of its user following tripping.
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Affiliation(s)
- Yasuhiro Akiyama
- Department of Mechanical Systems Engineering, Nagoya University, Nagoya, Aichi, Japan
- * E-mail:
| | - Yusuke Fukui
- Department of Mechanical Systems Engineering, Nagoya University, Nagoya, Aichi, Japan
| | - Shogo Okamoto
- Department of Mechanical Systems Engineering, Nagoya University, Nagoya, Aichi, Japan
| | - Yoji Yamada
- Department of Mechanical Systems Engineering, Nagoya University, Nagoya, Aichi, Japan
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Duong TTH, Zhang H, Lynch TS, Zanotto D. Improving the Accuracy of Wearable Sensors for Human Locomotion Tracking Using Phase-Locked Regression Models. IEEE Int Conf Rehabil Robot 2020; 2019:145-150. [PMID: 31374621 DOI: 10.1109/icorr.2019.8779428] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The trend toward soft wearable robotic systems creates a compelling need for new and reliable sensor systems that do not require a rigid mounting frame. Despite the growing use of inertial measurement units (IMUs) in motion tracking applications, sensor drift and IMU-to-segment misalignment still represent major problems in applications requiring high accuracy. This paper proposes a novel 2-step calibration method which takes advantage of the periodic nature of human locomotion to improve the accuracy of wearable inertial sensors in measuring lower-limb joint angles. Specifically, the method was applied to the determination of the hip joint angles during walking tasks. The accuracy and precision of the calibration method were accessed in a group of N =8 subjects who walked with a custom-designed inertial motion capture system at 85% and 115% of their comfortable pace, using an optical motion capture system as reference. In light of its low computational complexity and good accuracy, the proposed approach shows promise for embedded applications, including closed-loop control of soft wearable robotic systems.
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Jamwal PK, Hussain S, Ghayesh MH. Robotic orthoses for gait rehabilitation: An overview of mechanical design and control strategies. Proc Inst Mech Eng H 2020; 234:444-457. [PMID: 31916511 DOI: 10.1177/0954411919898293] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The application of robotic devices in providing physiotherapies to post-stroke patients and people suffering from incomplete spinal cord injuries is rapidly expanding. It is crucial to provide valid rehabilitation for people who are experiencing abnormality in their gait performance; therefore, design and development of newer robotic devices for the purpose of facilitating patients' recovery is being actively researched. In order to advance the traditional gait treatment among patients, exoskeletons and orthoses were introduced over the last two decades. This article presents a thorough review of existing robotic gait rehabilitation devices. The latest advancements in the mechanical design, types of control and actuation are also covered. The study comprehends discussions on robotic rehabilitation devices developed both for the training on treadmill and over-ground training. The assist-as-needed strategy for the gait training is particularly emphasized while reviewing various control strategies applied to these robotic devices. This study further reviews experimental investigations and clinical assessments of different control strategies and mechanism designs of robotic gait rehabilitation devices using experimental and clinical trials.
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Affiliation(s)
- Prashant K Jamwal
- Department of Electrical and Computer Engineering, Nazarbayev University, Astana, Kazakhstan
| | - Shahid Hussain
- Human-Centred Technology Research Centre, Faculty of Science and Technology, University of Canberra, Canberra, ACT, Australia
| | - Mergen H Ghayesh
- School of Mechanical Engineering, The University of Adelaide, Adelaide, SA, Australia
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Zhang Q, Kim K, Sharma N. Prediction of Ankle Dorsiflexion Moment by Combined Ultrasound Sonography and Electromyography. IEEE Trans Neural Syst Rehabil Eng 2020; 28:318-327. [DOI: 10.1109/tnsre.2019.2953588] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Andrade RM, Sapienza S, Bonato P. Development of a "transparent operation mode" for a lower-limb exoskeleton designed for children with cerebral palsy. IEEE Int Conf Rehabil Robot 2019; 2019:512-517. [PMID: 31374681 DOI: 10.1109/icorr.2019.8779432] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Robot-assisted rehabilitation in children and young adults with Cerebral Palsy (CP) is expected to lead to neuroplasticity and reduce the burden of motor impairments. For a lower-limb exoskeleton to perform well in this context, it is essential that the robot be "transparent" to the user and produce torques only when voluntarily-generated motor outputs deviate significantly from the target trajectory. However, the development of transparent operation modes and assistance-as-need control schema are still open problems with several implementation challenges. This paper presents a theoretical approach and provides a discussion of the key issues pertinent to designing a transparent operation mode for a lower-limb exoskeleton suitable for children and young adults with CP. Based on the dynamics of exoskeletons as well as friction models and human-robot interaction models, we propose a control strategy aimed to minimize human-machine interaction forces when subjects generate motor outputs that match the target trajectory. The material is presented as a conceptual framework that can be generalized to other exoskeleton systems for overground walking.
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Li J, Zuo S, Xu C, Zhang L, Dong M, Tao C, Ji R. Influence of a Compatible Design on Physical Human-Robot Interaction Force: a Case Study of a Self-Adapting Lower-Limb Exoskeleton Mechanism. J INTELL ROBOT SYST 2019. [DOI: 10.1007/s10846-019-01063-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Yandell MB, Tacca JR, Zelik KE. Design of a Low Profile, Unpowered Ankle Exoskeleton That Fits Under Clothes: Overcoming Practical Barriers to Widespread Societal Adoption. IEEE Trans Neural Syst Rehabil Eng 2019; 27:712-723. [PMID: 30872237 PMCID: PMC6592282 DOI: 10.1109/tnsre.2019.2904924] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Here, we present the design of a novel unpowered ankle exoskeleton that is low profile, lightweight, quiet, and low cost to manufacture, intrinsically adapts to different walking speeds, and does not restrict non-sagittal joint motion; while still providing assistive ankle torque that can reduce demands on the biological calf musculature. This paper is an extension of the previously-successful ankle exoskeleton concept by Collins, Wiggin, and Sawicki. We created a device that blends the torque assistance of the prior exoskeleton with the form-factor benefits of clothing. Our design integrates a low profile under-the-foot clutch and a soft conformal shank interface, coupled by an ankle assistance spring that operates in parallel with the user's calf muscles. We fabricated and characterized technical performance of a prototype through benchtop testing and then validated device functionality in two gait analysis case studies. To our knowledge, this is the first ankle plantarflexion assistance exoskeleton that could be feasibly worn under typical daily clothing, without restricting ankle motion, and without components protruding substantially from the shoe, leg, waist, or back. Our new design highlights the potential for performance-enhancing exoskeletons that are inexpensive, unobtrusive, and can be used on a wide scale to benefit a broad range of individuals throughout society, such as the elderly, individuals with impaired plantarflexor muscle strength, or recreational users. In summary, this paper demonstrates how an unpowered ankle exoskeleton could be redesigned to more seamlessly integrate into daily life, while still providing performance benefits for common locomotion tasks.
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Zhang Y, Nolan KJ, Zanotto D. Oscillator-Based Transparent Control of an Active/Semiactive Ankle-Foot Orthosis. IEEE Robot Autom Lett 2019. [DOI: 10.1109/lra.2018.2886400] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Enhanced neural network control of lower limb rehabilitation exoskeleton by add-on repetitive learning. Neurocomputing 2019. [DOI: 10.1016/j.neucom.2018.09.085] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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The Effects on Muscle Activity and Discomfort of Varying Load Carriage With and Without an Augmentation Exoskeleton. APPLIED SCIENCES-BASEL 2018. [DOI: 10.3390/app8122638] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Load carriage is a key risk factor for Muscular Skeletal Disorders (MSDs). As one way to decrease such injuries, some exoskeletons have been developed for regular load carriage. We examined the ergonomic potential of an augmentation exoskeleton. Nine subjects completed eight trials of carrying tasks, using four loading levels (0, 15, 30, and 45 kg) and two carrying conditions (with and without the exoskeleton). Electromyography (EMG) and the extended NASA-TLX rating scales were investigated and analyzed by linear mixed modeling and two-way ANOVA methods. Noraxon MR3.8, SPSS19.0, and MATLAB R2014b software were adapted. The results show that most of the muscle mean activities increased significantly (p < 0.05) with exoskeleton assistance. However, the interactive effects illustrate a decreasing trend with increase of load level. The mean discomfort rating scale values were generally higher, but subjects generally preferred using the exoskeleton in heavier loading tasks. The exoskeleton can effectively augment the performance of humans in heavy load carriage. The main reasons for higher muscle activity are from inflexible structures and inharmonious human–robot interactions. In order to decrease the MSD risks and increase comfort, optimal human–robot control strategies and adaptable kinematic design should be improved.
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Gordon DFN, Henderson G, Vijayakumar S. Effectively Quantifying the Performance of Lower-Limb Exoskeletons Over a Range of Walking Conditions. Front Robot AI 2018; 5:61. [PMID: 33644121 PMCID: PMC7904313 DOI: 10.3389/frobt.2018.00061] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Accepted: 05/07/2018] [Indexed: 11/13/2022] Open
Abstract
Exoskeletons and other wearable robotic devices have a wide range of potential applications, including assisting patients with walking pathologies, acting as tools for rehabilitation, and enhancing the capabilities of healthy humans. However, applying these devices effectively in a real-world setting can be challenging, as the optimal design features and control commands for an exoskeleton are highly dependent on the current user, task and environment. Consequently, robust metrics and methods for quantifying exoskeleton performance are required. This work presents an analysis of walking data collected for healthy subjects walking with an active pelvis exoskeleton over three assistance scenarios and five walking contexts. Spatial and temporal, kinematic, kinetic and other novel dynamic gait metrics were compared to identify which metrics exhibit desirable invariance properties, and so are good candidates for use as a stability metric over varying walking conditions. Additionally, using a model-based approach, the average metabolic power consumption was calculated for a subset of muscles crossing the hip, knee and ankle joints, and used to analyse how the energy-reducing properties of an exoskeleton are affected by changes in walking context. The results demonstrated that medio-lateral centre of pressure displacement and medio-lateral margin of stability exhibit strong invariance to changes in walking conditions. This suggests that these dynamic gait metrics are optimised in human gait and are potentially suitable metrics for optimising in an exoskeleton control paradigm. The effectiveness of the exoskeleton at reducing human energy expenditure was observed to increase when walking on an incline, where muscles aiding in hip flexion were assisted, but decrease when walking at a slow speed. These results underline the need for adaptive control algorithms for exoskeletons if they are to be used in varied environments.
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Affiliation(s)
- Daniel F. N. Gordon
- Institute of Perception, Action, and Behaviour, School of Informatics, University of Edinburgh, Edinburgh, United Kingdom
| | - Graham Henderson
- Institute of Perception, Action, and Behaviour, School of Informatics, University of Edinburgh, Edinburgh, United Kingdom
| | - Sethu Vijayakumar
- Institute of Perception, Action, and Behaviour, School of Informatics, University of Edinburgh, Edinburgh, United Kingdom
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