101
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Hu D, Xiong C, Wang T, Zhou T, Liang J, Li Y. Modulating Energy Among Foot-Ankle Complex With an Unpowered Exoskeleton Improves Human Walking Economy. IEEE Trans Neural Syst Rehabil Eng 2022; 30:1961-1970. [PMID: 35793296 DOI: 10.1109/tnsre.2022.3188870] [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: 11/10/2022]
Abstract
Over the course of both evolution and development, the human musculoskeletal system has been well shaped for the cushion function of the foot during foot-strike and the impulsive function of the ankle joint during push-off. Nevertheless, an efficient energy interaction between foot structure and ankle joint is still lacking in the human body itself, which may limit the further potential of economical walking. Here we showed the metabolic expenditure of walking can be lessened by an unpowered exoskeleton robot that modulates energy among the foot-ankle complex towards a more effective direction. The unpowered exoskeleton recycles negative mechanical energy of the foot that is normally dissipated in heel-strike, retains the stored energy before mid-stance, and then transfers the energy to the ankle joint to assist the push-off. The modulation process of the exoskeleton consumes no input energy, yet reduces the metabolic cost of walking by 8.19 ± 0.96 % (mean ± s.e.m) for healthy subjects. The electromyography measurements demonstrate the activities of target ankle plantarflexors decreased significantly without added effort for the antagonistic muscle, suggesting the exoskeleton enhanced the subjects' energy efficiency of the foot-ankle complex in a natural manner. Furthermore, the exoskeleton also provides cushion assistance for walking, which leads to significantly decreased activity of the quadriceps muscle during heel-strike. Rather than strengthening the functions of existing biological structures, developing the complementary energy loop that does not exist in the human body itself also shows its potential for gait assistance.
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102
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Koelewijn AD, Selinger JC. Predictive Simulations to Replicate Human Gait Adaptations and Energetics With Exoskeletons. IEEE Trans Neural Syst Rehabil Eng 2022; 30:1931-1940. [PMID: 35797329 DOI: 10.1109/tnsre.2022.3189038] [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: 11/07/2022]
Abstract
Robotic exoskeletons have the potential to restore and enhance human mobility. However, optimally controlling these devices, to work in concert with human users, is challenging. Accurate model simulations of the interaction between exoskeletons and users may expedite the design process and improve control. Here, as a proof of principle, we tested if we could use predictive simulations to replicate human gait adaptations and changes in energy expenditure from an experiment where participants walked with exoskeletons. We recreated a past experimental paradigm, where robotic exoskeletons were used to shift people's energetically optimal step frequency to frequencies higher and lower than normally preferred. To match the experimental controller, we modelled knee-worn exoskeletons that applied resistive torques, either proportional or inversely proportional to step frequency-decreasing or increasing the energy optimal step frequency, respectively. We were able to replicate the experiment, finding higher and lower optimal step frequencies than in natural walking under each respective condition. Our simulated resistive torques and objective landscapes resembled the measured experimental resistive torque and energy landscapes. Individual muscle energetics revealed distinct coordination strategies consistent with each exoskeleton controller condition. Increasing the accuracy of step frequency and energetic predictions was best achieved by increasing the number of virtual participants (varying whole-body anthropometrics), rather than the number of muscle parameter sets (varying muscle anthropometrics). In future, our approach can be used to design controllers in advance of human testing, to help identify reasonable solution spaces or tailor design to individual users.
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103
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Abstract
The exoskeleton is often regarded as a tool for rehabilitation and assistance of human movement. The control schemes were conventionally implemented by developing accurate physical and kinematic models, which often lack robustness to external variational disturbing forces. This paper presents a virtual neuromuscular control for robotic ankle exoskeleton standing balance. The robustness of the proposed method was improved by applying a specific virtual neuromuscular model to estimate the desired ankle torques for ankle exoskeleton standing balance control. In specialty, the proposed control method has two key components, including musculoskeletal mechanics and neural control. A simple version of the ankle exoskeleton was designed, and three sets of comparative experiments were carried out. The experimentation results demonstrated that the proposed virtual neuromuscular control could effectively reduce the wearer’s lower limb muscle activation, and improve the robustness of the different external disturbances.
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104
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Yang C, Yu L, Xu L, Yan Z, Hu D, Zhang S, Yang W. Current developments of robotic hip exoskeleton toward sensing, decision, and actuation: A review. WEARABLE TECHNOLOGIES 2022; 3:e15. [PMID: 38486916 PMCID: PMC10936331 DOI: 10.1017/wtc.2022.11] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 05/22/2022] [Accepted: 06/09/2022] [Indexed: 03/17/2024]
Abstract
The aging population is now a global challenge, and impaired walking ability is a common feature in the elderly. In addition, some occupations such as military and relief workers require extra physical help to perform tasks efficiently. Robotic hip exoskeletons can support ambulatory functions in the elderly and augment human performance in healthy people during normal walking and loaded walking by providing assistive torque. In this review, the current development of robotic hip exoskeletons is presented. In addition, the framework of actuation joints and the high-level control strategy (including the sensors and data collection, the way to recognize gait phase, the algorithms to generate the assist torque) are described. The exoskeleton prototypes proposed by researchers in recent years are organized to benefit the related fields realizing the limitations of the available robotic hip exoskeletons, therefore, this work tends to be an influential factor with a better understanding of the development and state-of-the-art technology.
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Affiliation(s)
- Canjun Yang
- Ningbo Research Institute, Zhejiang University, Ningbo, China
- School of Mechanical Engineering, Zhejiang University, Hangzhou, China
- School of Mechanical and Energy Engineering, NingboTech University, Ningbo, China
| | - Linfan Yu
- Ningbo Research Institute, Zhejiang University, Ningbo, China
- School of Mechanical Engineering, Zhejiang University, Hangzhou, China
| | - Linghui Xu
- Ningbo Research Institute, Zhejiang University, Ningbo, China
- School of Mechanical Engineering, Zhejiang University, Hangzhou, China
| | - Zehao Yan
- Ningbo Research Institute, Zhejiang University, Ningbo, China
- School of Mechanical Engineering, Zhejiang University, Hangzhou, China
| | - Dongming Hu
- School of Mechanical and Energy Engineering, NingboTech University, Ningbo, China
| | - Sheng Zhang
- Ningbo Research Institute, Zhejiang University, Ningbo, China
- School of Mechanical Engineering, Zhejiang University, Hangzhou, China
| | - Wei Yang
- Ningbo Research Institute, Zhejiang University, Ningbo, China
- School of Mechanical Engineering, Zhejiang University, Hangzhou, China
- School of Mechanical and Energy Engineering, NingboTech University, Ningbo, China
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105
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Ben-David C, Ostraich B, Riemer R. Passive Knee Exoskeleton Increases Vertical Jump Height. IEEE Trans Neural Syst Rehabil Eng 2022; 30:1796-1805. [PMID: 35776830 DOI: 10.1109/tnsre.2022.3187056] [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: 11/07/2022]
Abstract
Most exoskeletons are designed to reduce the metabolic costs of performing aerobic tasks such as walking, running, and hopping. This study presents an exoskeleton that boosts vertical jumping-a fast, short movement during which the muscles are exerted at peak capacity. It was hypothesized that a passive exoskeleton would increase vertical jump height without requiring external energy input. The device comprises springs that work in parallel with the muscles of the quadriceps femoris. The springs store mechanical energy during knee flexion (the negative work phase) and release that energy during the subsequent knee extension (the positive work phase), augmenting the muscles. Ten healthy participants were evaluated in two experimental sessions. In the first session, the participants jumped without receiving instructions on how to use the exoskeleton, and the results showed no difference in jump height when jumping with the exoskeleton or jumping without it. In the second session, the participants were instructed to achieve deeper initial squat heights at the start of the jump. This resulted in a 6.4% increase in average jump height compared to jumping without the exoskeleton (each participant performed five jumps for each the two conditions). This is the first time that a passive exoskeleton has been shown to improve the height of a vertical jump from a dead stop.
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106
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Muscle coordination retraining inspired by musculoskeletal simulations reduces knee contact force. Sci Rep 2022; 12:9842. [PMID: 35798755 PMCID: PMC9262899 DOI: 10.1038/s41598-022-13386-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Accepted: 05/24/2022] [Indexed: 11/24/2022] Open
Abstract
Humans typically coordinate their muscles to meet movement objectives like minimizing energy expenditure. In the presence of pathology, new objectives gain importance, like reducing loading in an osteoarthritic joint, but people often do not change their muscle coordination patterns to meet these new objectives. Here we use musculoskeletal simulations to identify simple changes in coordination that can be taught using electromyographic biofeedback, achieving the therapeutic goal of reducing joint loading. Our simulations predicted that changing the relative activation of two redundant ankle plantarflexor muscles—the gastrocnemius and soleus—could reduce knee contact force during walking, but it was unclear whether humans could re-coordinate redundant muscles during a complex task like walking. Our experiments showed that after a single session of walking with biofeedback of summary measures of plantarflexor muscle activation, healthy individuals reduced the ratio of gastrocnemius-to-soleus muscle activation by 25 ± 15% (p = 0.004, paired t test, n = 10). Participants who walked with this “gastrocnemius avoidance” gait pattern reduced late-stance knee contact force by 12 ± 12% (p = 0.029, paired t test, n = 8). Simulation-informed coordination retraining could be a promising treatment for knee osteoarthritis and a powerful tool for optimizing coordination for a variety of rehabilitation and performance applications.
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107
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Adeyeri B, Thomas SA, Arellano CJ. A simple method reveals minimum time required to quantify steady-rate metabolism and net cost of transport for human walking. J Exp Biol 2022; 225:275934. [PMID: 35796105 DOI: 10.1242/jeb.244471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Accepted: 06/29/2022] [Indexed: 11/20/2022]
Abstract
The U-shaped net cost of transport (COT) curve of walking has helped scientists understand the biomechanical basis that underlies energy minimization during walking. However, to produce an individual's net COT curve, data must be analyzed during periods of steady-rate metabolism. Traditionally, studies analyze the last few minutes of a 6-10 min trial, assuming that steady-rate metabolism has been achieved. Yet, it is possible that an individual achieves steady rates of metabolism much earlier. However, there is no consensus on how to objectively quantify steady-rate metabolism across a range of walking speeds. Therefore, we developed a simple slope method to determine the minimum time needed for humans to achieve steady rates of metabolism across slow to fast walking speeds. We hypothesized that a shorter time window could be used to produce a net COT curve that is comparable to the net COT curve created using traditional methods. We analyzed metabolic data from twenty-one subjects who completed several 7-min walking trials ranging from 0.50-2.00 m/s. We partitioned the metabolic data for each trial into moving 1-min, 2-min, and 3 min intervals and calculated their slopes. We statistically compared these slope values to values derived from the last 3-min of the 7-min trial, our 'gold' standard comparison. We found that a minimum of 2 min is required to achieve steady-rate metabolism and that data from 2-4 min yields a net COT curve that is not statistically different from the one derived from experimental protocols that are generally accepted in the field.
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Affiliation(s)
- Bolatito Adeyeri
- Center for Neuromotor and Biomechanics Research, University of Houston, Houston, TX, USA.,Department of Health and Human Performance, University of Houston, Houston, TX, USA
| | - Shernice A Thomas
- Center for Neuromotor and Biomechanics Research, University of Houston, Houston, TX, USA.,Department of Health and Human Performance, University of Houston, Houston, TX, USA
| | - Christopher J Arellano
- Center for Neuromotor and Biomechanics Research, University of Houston, Houston, TX, USA.,Department of Health and Human Performance, University of Houston, Houston, TX, USA
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108
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Wu M, Qiu Y, Ueda J, Ting LH. A Versatile Emulator for Haptic Communication to Alter Human Gait Parameters. IEEE Robot Autom Lett 2022. [DOI: 10.1109/lra.2022.3182109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Mengnan Wu
- W. H. Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, GA, USA
| | - Yingxin Qiu
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA
| | - Jun Ueda
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA
| | - Lena H. Ting
- W. H. Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, GA, USA
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109
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Almani MN, Saxena S. Recurrent neural networks controlling musculoskeletal models predict motor cortex activity during novel limb movements. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2022; 2022:3350-3356. [PMID: 36086532 DOI: 10.1109/embc48229.2022.9871085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Goal-driven networks trained to perform a task analogous to that performed by biological neural populations are being increasingly utilized as insightful computational models of motor control. The resulting dynamics of the trained networks are then analyzed to uncover the neural strategies employed by the motor cortex to produce movements. However, these networks do not take into account the role of sensory feedback in producing movement, nor do they consider the complex biophysical underpinnings of the underlying musculoskeletal system. Moreover, these models can not be used in context of predictive neuromechanical simulations for hypothesis generation and prediction of neural strategies during novel movements. In this research, we adapt state-of-the-art deep reinforcement learning (DRL) algorithms to train a controller to drive a developed anatomically accurate monkey arm model to track experimentally recorded kinematics. We validate that the trained controller mimics biologically observed neural strategies to produce movement. The trained controller generalizes well to unobserved conditions as well as to perturbation analyses. The recorded firing rates of motor cortex neurons can be predicted from the controller activity with high accuracy even on unseen conditions. Finally, we validate that the trained controller outperforms existing goal-driven and representational models of motor cortex in single neuron decoding accuracy, thus showing the utility of the complex underpinnings of anatomically accurate models in shaping motor cortex neural activity during limb movements. The learned controller can be used for hypothesis generation and prediction of neural strategies during novel movements and unobserved conditions.
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110
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Medrano RL, Thomas GC, Rouse EJ, Gregg RD. Analysis of the Bayesian Gait-State Estimation Problem for Lower-Limb Wearable Robot Sensor Configurations. IEEE Robot Autom Lett 2022; 7:7463-7470. [PMID: 35782346 PMCID: PMC9246062 DOI: 10.1109/lra.2022.3183790] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2023]
Abstract
Many exoskeletons today are primarily tested in controlled, steady-state laboratory conditions that are unrealistic representations of their real-world usage in which walking conditions (e.g., speed, slope, and stride length) change constantly. One potential solution is to detect these changing walking conditions online using Bayesian state estimation to deliver assistance that continuously adapts to the wearer's gait. This paper investigates such an approach in silico, aiming to understand 1) which of the various Bayesian filter assumptions best match the problem, and 2) which gait parameters can be feasibly estimated with different combinations of sensors available to different exoskeleton configurations (pelvis, thigh, shank, and/or foot). Our results suggest that the assumptions of the Extended Kalman Filter are well suited to accurately estimate phase, stride frequency, stride length, and ramp inclination with a wide variety of sparse sensor configurations.
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Affiliation(s)
- Roberto Leo Medrano
- Department of Mechanical Engineering and the Robotics Institute, University of Michigan, Ann Arbor, MI 48109 USA
| | - Gray Cortright Thomas
- Department of Electrical Engineering and Computer Science and the Robotics Institute, University of Michigan, Ann Arbor, MI 48109 USA
| | - Elliott J. Rouse
- Department of Mechanical Engineering and the Robotics Institute, University of Michigan, Ann Arbor, MI 48109 USA
| | - Robert D. Gregg
- Department of Electrical Engineering and Computer Science and the Robotics Institute, University of Michigan, Ann Arbor, MI 48109 USA
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111
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Tomc M, Zadravec M, Olensek A, Matjacic Z. Harnessing Energy of a Treadmill for Push-Off Assistance During Walking: a Proof of Concept study. IEEE Int Conf Rehabil Robot 2022; 2022:1-6. [PMID: 36176127 DOI: 10.1109/icorr55369.2022.9896554] [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: 06/16/2023]
Abstract
Various approaches in ankle exoskeleton design and control have recently been proposed and implemented, but few have been able to produce devices suitable for rehabilitation in clinical environment. In a recent in-silico study, we proposed a novel device: Ankle Exoskeleton using Treadmill Actuation for Push-off assistance (AN-EXTRA-Push). Using a brake and an elastic tendon, it harnesses energy of a moving treadmill during stance phase, then releases it during push-off to aid with plantarflexion torque generation. Simulation studies suggest inherent synchrony between the body's own efforts and ANEXTRA-Push assistance, allowing for intuitive use and simple control of the device. In this contribution we describe a mock-up device and the findings of a proof of concept study. Kinematics, ground reaction forces, interaction forces and EMG signals were measured for one subject walking with AN-EXTRA-Push with different levels of assistance. Using AN-EXTRA-Push did not result in substantial changes in the subject's kinematics and the activity of ankle plantarflexor muscles was successfully reduced. Preliminary results suggest that the concept is promising and appear to confirm the conclusions drawn from our previous simulation study.
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112
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Bacek T, Sun M, Liu H, Chen Z, Kulic D, Oetomo D, Tan Y. Varying Joint Patterns and Compensatory Strategies Can Lead to the Same Functional Gait Outcomes: A Case Study. IEEE Int Conf Rehabil Robot 2022; 2022:1-6. [PMID: 36176172 DOI: 10.1109/icorr55369.2022.9896497] [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: 06/16/2023]
Abstract
This paper analyses joint-space walking mechanisms and redundancies in delivering functional gait outcomes. Multiple biomechanical measures are analysed for two healthy male adults who participated in a multi-factorial study and walked during three sessions. Both participants employed varying intra- and inter-personal compensatory strategies (e.g., vaulting, hip hiking) across walking conditions and exhibited notable gait pattern alterations while keeping task-space (functional) gait parameters invariant. They also preferred various levels of asymmetric step length but kept their symmetric step time consistent and cadence-invariant during free walking. The results demonstrate the importance of an individualised approach and the need for a paradigm shift from functional (task-space) to joint-space gait analysis in attending to (a)typical gaits and delivering human-centred human-robot interaction.
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113
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Foot contact forces can be used to personalize a wearable robot during human walking. Sci Rep 2022; 12:10947. [PMID: 35768457 PMCID: PMC9243054 DOI: 10.1038/s41598-022-14776-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Accepted: 06/13/2022] [Indexed: 11/09/2022] Open
Abstract
Individuals with below-knee amputation (BKA) experience increased physical effort when walking, and the use of a robotic ankle-foot prosthesis (AFP) can reduce such effort. The walking effort could be further reduced if the robot is personalized to the wearer using human-in-the-loop (HIL) optimization of wearable robot parameters. The conventional physiological measurement, however, requires a long estimation time, hampering real-time optimization due to the limited experimental time budget. This study hypothesized that a function of foot contact force, the symmetric foot force-time integral (FFTI), could be used as a cost function for HIL optimization to rapidly estimate the physical effort of walking. We found that the new cost function presents a reasonable correlation with measured metabolic cost. When we employed the new cost function in HIL ankle-foot prosthesis stiffness parameter optimization, 8 individuals with simulated amputation reduced their metabolic cost of walking, greater than 15% (p < 0.02), compared to the weight-based and control-off conditions. The symmetry cost using the FFTI percentage was lower for the optimal condition, compared to all other conditions (p < 0.05). This study suggests that foot force-time integral symmetry using foot pressure sensors can be used as a cost function when optimizing a wearable robot parameter.
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114
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Kim J, Quinlivan BT, Deprey LA, Arumukhom Revi D, Eckert-Erdheim A, Murphy P, Orzel D, Walsh CJ. Reducing the energy cost of walking with low assistance levels through optimized hip flexion assistance from a soft exosuit. Sci Rep 2022; 12:11004. [PMID: 35768486 PMCID: PMC9243082 DOI: 10.1038/s41598-022-14784-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Accepted: 06/13/2022] [Indexed: 11/09/2022] Open
Abstract
As we age, humans see natural decreases in muscle force and power which leads to a slower, less efficient gait. Improving mobility for both healthy individuals and those with muscle impairments/weakness has been a goal for exoskeleton designers for decades. In this work, we discover that significant reductions in the energy cost required for walking can be achieved with almost 50% less mechanical power compared to the state of the art. This was achieved by leveraging human-in-the-loop optimization to understand the importance of individualized assistance for hip flexion, a relatively unexplored joint motion. Specifically, we show that a tethered hip flexion exosuit can reduce the metabolic rate of walking by up to 15.2 ± 2.6%, compared to locomotion with assistance turned off (equivalent to 14.8% reduction compared to not wearing the exosuit). This large metabolic reduction was achieved with surprisingly low assistance magnitudes (average of 89 N, ~ 24% of normal hip flexion torque). Furthermore, the ratio of metabolic reduction to the positive exosuit power delivered was 1.8 times higher than ratios previously found for hip extension and ankle plantarflexion. These findings motivated the design of a lightweight (2.31 kg) and portable hip flexion assisting exosuit, that demonstrated a 7.2 ± 2.9% metabolic reduction compared to walking without the exosuit. The high ratio of metabolic reduction to exosuit power measured in this study supports previous simulation findings and provides compelling evidence that hip flexion may be an efficient joint motion to target when considering how to create practical and lightweight wearable robots to support improved mobility.
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Affiliation(s)
- Jinsoo Kim
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Boston, 02134, USA
| | - Brendan T Quinlivan
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Boston, 02134, USA
| | - Lou-Ana Deprey
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Boston, 02134, USA
- School of Life Sciences, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland
| | - Dheepak Arumukhom Revi
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Boston, 02134, USA
- Department of Mechanical Engineering, Boston University, Boston, 02215, USA
- College of Health and Rehabilitation Sciences: Sargent College, Boston University, Boston, 02215, USA
| | - Asa Eckert-Erdheim
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Boston, 02134, USA
| | - Patrick Murphy
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Boston, 02134, USA
| | - Dorothy Orzel
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Boston, 02134, USA
| | - Conor J Walsh
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Boston, 02134, USA.
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115
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A dual-drive four joint time-sharing control walking power-assisted flexible exoskeleton robot system. ROBOTICA 2022. [DOI: 10.1017/s0263574722000704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Abstract
Exoskeleton robot can assist people and reduce energy consumption when they walk with heavy weight, so as to protect their health and travel longer distances. This work analyzes the cross gait during walking and designs a dual-drive four joint time-sharing assistance exoskeleton system, which controls the four joints through two motors to realize the assistance to the wearer’s movement process. The control curve and adaptive control algorithm are designed to help different people with various walking gaits and speeds, the effectiveness of exoskeleton system is proved by testing metabolism. When the exoskeleton wearer carries 25 kg weight (load equal to 36% of body mass) and travels at the average speed of 5 km/h, the metabolic rate of the exoskeleton wearers decreases by an average of 7.79%, the reduction magnitude is comparable to the effect of taking off 7.33 kg during walking.
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116
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Fang Y, Orekhov G, Lerner ZF. Adaptive ankle exoskeleton gait training demonstrates acute neuromuscular and spatiotemporal benefits for individuals with cerebral palsy: A pilot study. Gait Posture 2022; 95:256-263. [PMID: 33248858 PMCID: PMC8110598 DOI: 10.1016/j.gaitpost.2020.11.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 10/05/2020] [Accepted: 11/04/2020] [Indexed: 02/02/2023]
Abstract
BACKGROUND Gait abnormalities from neuromuscular conditions like cerebral palsy (CP) limit mobility and negatively affect quality of life. Increasing walking speed and stride length are essential clinical goals in the treatment of gait disorders from CP. RESEARCH QUESTION How does over-ground gait training with an untethered ankle exoskeleton providing adaptive assistance affect mobility-related spatiotemporal outcomes and lower-extremity muscle activity in people with CP? METHODS A diverse cohort of individuals with CP (n = 6, age 9-31, Gross Motor Function Classification System Level I - III) completed four over-ground training sessions (98 ± 17 min of assisted walking) and received pre- and post-training assessments. On both assessments, participants walked over-ground with and without the exoskeleton while we recorded spatiotemporal outcomes and muscle activity. We used two-tailed paired t-tests to compare all parameters pre- and post-training, and between assisted and unassisted conditions. RESULTS Following training, walking speed increased 0.24 m/s (p = 0.006) and stride length increased 0.17 m (p = 0.013) during unassisted walking, while walking speed increased 0.28 m/s (p = 0.023) and stride length increased 0.15 m (p = 0.002) during exoskeleton-assisted walking. Exoskeleton training improved stride-to-stride repeatability of soleus and vastus lateralis muscle activation by up to 51 % (p ≤ 0.046), while the amount of integrated stance-phase muscle activity was similar across visits and conditions. Relative to baseline, post-training walking with the exoskeleton resulted in a soleus activity pattern that was 39 % more similar to the typical pattern from unimpaired individuals (p < 0.001). SIGNIFICANCE This study demonstrates acute spatiotemporal and neuromuscular benefits from over-ground training with adaptive ankle exoskeleton assistance, and provides rationale for completion of a longer randomized controlled training protocol.
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Affiliation(s)
- Ying Fang
- Department of Mechanical Engineering, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - Greg Orekhov
- Department of Mechanical Engineering, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - Zachary F. Lerner
- Department of Mechanical Engineering, Northern Arizona University, Flagstaff, AZ 86011, USA,Department of Orthopedics, the University of Arizona College of Medicine-Phoenix, Phoenix, AZ 85004, USA
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117
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Durandau G, Rampeltshammer WF, Kooij HVD, Sartori M. Neuromechanical Model-Based Adaptive Control of Bilateral Ankle Exoskeletons: Biological Joint Torque and Electromyogram Reduction Across Walking Conditions. IEEE T ROBOT 2022. [DOI: 10.1109/tro.2022.3170239] [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)
- Guillaume Durandau
- Department of Biomechanical Engineering, Technical Medical Centre, University of Twente, Enschede, NB, The Netherlands
| | - Wolfgang F. Rampeltshammer
- Department of Biomechanical Engineering, Technical Medical Centre, University of Twente, Enschede, NB, The Netherlands
| | - Herman van der Kooij
- Department of Biomechanical Engineering, Technical Medical Centre, University of Twente, Enschede, NB, The Netherlands
| | - Massimo Sartori
- Department of Biomechanical Engineering, Technical Medical Centre, University of Twente, Enschede, NB, The Netherlands
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118
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Wade L, Birch J, Farris DJ. Walking with increasing acceleration is achieved by tuning ankle torque onset timing and rate of torque development. JOURNAL OF THE ROYAL SOCIETY, INTERFACE 2022; 19:20220035. [PMID: 35765807 PMCID: PMC9240669 DOI: 10.1098/rsif.2022.0035] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Understanding the mechanics of torque production about the ankle during accelerative gait is key to designing effective clinical and rehabilitation practices, along with developing functional robotics and wearable assistive technologies. We aimed to explore how torque and work about the ankle is produced as walking acceleration increases from 0 to 100% maximal acceleration. We hypothesized that as acceleration increased, greater work about the ankle would not be solely due to ramping up plantar flexor torque, and instead would be a product of adjustments to relative timing of ankle torque and angular displacement. Fifteen healthy participants performed walking without acceleration (constant speed), as well as low, moderate and maximal accelerations, while motion capture and ground reaction force data were recorded. We employed vector coding in a novel application to overcome limitations of previously employed evaluation methods. As walking acceleration increased, there was reduced negative work and increased positive work about the ankle. Furthermore, early stance dorsiflexion had reducing plantar flexor torque due to delayed plantar flexor torque onset as acceleration increased, while mid-stance ankle plantar flexor torque was substantially increased with minimal ankle dorsiflexion, irrespective of acceleration magnitude. Assistive devices need to account for these changes during accelerative walking to facilitate functional gait.
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Affiliation(s)
- Logan Wade
- Department for Health, University of Bath, Bath, UK.,Centre for Analysis of Motion, Entertainment Research and Applications, University of Bath, Bath, UK.,School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Jonathon Birch
- School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, Queensland, Australia.,Sport and Health Sciences, University of Exeter, Exeter, UK
| | - Dominic James Farris
- School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, Queensland, Australia.,Sport and Health Sciences, University of Exeter, Exeter, UK
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119
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Lora-Millan JS, Moreno JC, Rocon E. Coordination Between Partial Robotic Exoskeletons and Human Gait: A Comprehensive Review on Control Strategies. Front Bioeng Biotechnol 2022; 10:842294. [PMID: 35694226 PMCID: PMC9174608 DOI: 10.3389/fbioe.2022.842294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 04/28/2022] [Indexed: 12/02/2022] Open
Abstract
Lower-limb robotic exoskeletons have become powerful tools to assist or rehabilitate the gait of subjects with impaired walking, even when they are designed to act only partially over the locomotor system, as in the case of unilateral or single-joint exoskeletons. These partial exoskeletons require a proper method to synchronize their assistive actions and ensure correct inter-joint coordination with the user’s gait. This review analyzes the state of the art of control strategies to coordinate the assistance provided by these partial devices with the actual gait of the wearers. We have analyzed and classified the different approaches independently of the hardware implementation, describing their basis and principles. We have also reviewed the experimental validations of these devices for impaired and unimpaired walking subjects to provide the reader with a clear view of their technology readiness level. Eventually, the current state of the art and necessary future steps in the field are summarized and discussed.
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Affiliation(s)
- Julio S. Lora-Millan
- Centre for Automation and Robotics, Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Madrid, CSIC-UPM, Madrid, Spain
- Electronic Technology Department, Universidad Rey Juan Carlos, Madrid, Spain
| | - Juan C. Moreno
- Neural Rehabilitation Group, Cajal Institute, Spanish National Research Council (CSIC), Madrid, Spain
| | - E. Rocon
- Centre for Automation and Robotics, Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Madrid, CSIC-UPM, Madrid, Spain
- *Correspondence: E. Rocon,
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120
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Miller DE, Tan GR, Farina EM, Sheets-Singer AL, Collins SH. Characterizing the relationship between peak assistance torque and metabolic cost reduction during running with ankle exoskeletons. J Neuroeng Rehabil 2022; 19:46. [PMID: 35549977 PMCID: PMC9096774 DOI: 10.1186/s12984-022-01023-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Accepted: 04/26/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Reducing the energy cost of running with exoskeletons could improve enjoyment, reduce fatigue, and encourage participation among novice and ageing runners. Previously, tethered ankle exoskeleton emulators with offboard motors were used to greatly reduce the energy cost of running with powered ankle plantarflexion assistance. Through a process known as "human-in-the-loop optimization", the timing and magnitude of assistance torque was optimized to maximally reduce metabolic cost. However, to achieve the maximum net benefit in energy cost outside of the laboratory environment, it is also necessary to consider the tradeoff between the magnitude of device assistance and the metabolic penalty of carrying a heavier, more powerful exoskeleton. METHODS In this study, tethered ankle exoskeleton emulators were used to characterize the effect of peak assistance torque on metabolic cost during running. Three recreational runners participated in human-in-the-loop optimization at four fixed peak assistance torque levels to obtain their energetically optimal assistance timing parameters at each level. RESULTS We found that the relationship between metabolic rate and peak assistance torque was nearly linear but with diminishing returns at higher torque magnitudes, which is well-approximated by an asymptotic exponential function. At the highest assistance torque magnitude of 0.8 Nm/kg, participants' net metabolic rate was 24.8 ± 2.3% (p = 4e-6) lower than running in the unpowered devices. Optimized timing of peak assistance torque was as late as allowed during stance (80% of stance) and optimized timing of torque removal was at toe-off (100% of stance); similar assistance timing was preferred across participants and torque magnitudes. CONCLUSIONS These results allow exoskeleton designers to predict the energy cost savings for candidate devices with different assistance torque capabilities, thus informing the design of portable ankle exoskeletons that maximize net metabolic benefit.
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Affiliation(s)
- Delaney E Miller
- Department of Mechanical Engineering, Stanford University, Stanford, CA, USA.
| | - Guan Rong Tan
- Department of Mechanical Engineering, Stanford University, Stanford, CA, USA
| | - Emily M Farina
- Sports Research Laboratory, Nike Inc., Beaverton, OR, USA
| | | | - Steven H Collins
- Department of Mechanical Engineering, Stanford University, Stanford, CA, USA
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121
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Huang J, Cao Y, Wang YW. Adaptive proxy-based sliding mode control for a class of second-order nonlinear systems and its application to pneumatic muscle actuators. ISA TRANSACTIONS 2022; 124:395-402. [PMID: 33032793 DOI: 10.1016/j.isatra.2020.09.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 09/22/2020] [Accepted: 09/23/2020] [Indexed: 06/11/2023]
Abstract
The human-centered robotic systems demand safe and robust controllers in many applications. This paper proposes an adaptive proxy-based sliding mode control approach for a class of typical second-order nonlinear systems. A new PID-type virtual coupling is designed between a virtual proxy and the physical object. Considering the unknown bound of lumped disturbances, an adaptation law is applied to online adjust the gain of a sign function which ensures the proxy to track the reference accurately. By using the Lyapunov theorem, the closed-loop system stability is proved. Both simulations and experiments are conducted to verify the proposed method based on a real-world pneumatic muscle actuator control platform. The results show that the proposed adaptive proxy-based sliding mode control approach presents better tracking accuracy, safety, and robustness than the conventional PID control and sliding mode control.
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Affiliation(s)
- Jian Huang
- Key Laboratory of Ministry of Education for Image Processing and Intelligent Control, School of Artificial Intelligence and Automation, Huazhong University of Science and Technology, Wuhan, China.
| | - Yu Cao
- Key Laboratory of Ministry of Education for Image Processing and Intelligent Control, School of Artificial Intelligence and Automation, Huazhong University of Science and Technology, Wuhan, China.
| | - Yan-Wu Wang
- Key Laboratory of Ministry of Education for Image Processing and Intelligent Control, School of Artificial Intelligence and Automation, Huazhong University of Science and Technology, Wuhan, China.
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122
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Miller-Jackson TM, Natividad RF, Lim DYL, Hernandez-Barraza L, Ambrose JW, Yeow RCH. A Wearable Soft Robotic Exoskeleton for Hip Flexion Rehabilitation. Front Robot AI 2022; 9:835237. [PMID: 35572371 PMCID: PMC9096701 DOI: 10.3389/frobt.2022.835237] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Accepted: 03/21/2022] [Indexed: 11/13/2022] Open
Abstract
Leg motion is essential to everyday tasks, yet many face a daily struggle due to leg motion impairment. Traditional robotic solutions for lower limb rehabilitation have arisen, but they may bare some limitations due to their cost. Soft robotics utilizes soft, pliable materials which may afford a less costly robotic solution. This work presents a soft-pneumatic-actuator-driven exoskeleton for hip flexion rehabilitation. An array of soft pneumatic rotary actuators is used for torque generation. An analytical model of the actuators is validated and used to determine actuator parameters for the target application of hip flexion. The performance of the assembly is assessed, and it is found capable of the target torque for hip flexion, 19.8 Nm at 30°, requiring 86 kPa to reach that torque output. The assembly exhibits a maximum torque of 31 Nm under the conditions tested. The full exoskeleton assembly is then assessed with healthy human subjects as they perform a set of lower limb motions. For one motion, the Leg Raise, a muscle signal reduction of 43.5% is observed during device assistance, as compared to not wearing the device. This reduction in muscle effort indicates that the device is effective in providing hip flexion assistance and suggests that pneumatic-rotary-actuator-driven exoskeletons are a viable solution to realize more accessible options for those who suffer from lower limb immobility.
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Affiliation(s)
- Tiana M. Miller-Jackson
- Evolution Innovation Lab, Advanced Robotics Centre, National University of Singapore, Singapore
- Department of Biomedical Engineering, National University of Singapore, Singapore
| | - Rainier F. Natividad
- Evolution Innovation Lab, Advanced Robotics Centre, National University of Singapore, Singapore
- Department of Biomedical Engineering, National University of Singapore, Singapore
| | - Daniel Yuan Lee Lim
- Evolution Innovation Lab, Advanced Robotics Centre, National University of Singapore, Singapore
- Department of Biomedical Engineering, National University of Singapore, Singapore
| | - Luis Hernandez-Barraza
- Evolution Innovation Lab, Advanced Robotics Centre, National University of Singapore, Singapore
- Department of Biomedical Engineering, National University of Singapore, Singapore
| | - Jonathan W. Ambrose
- Evolution Innovation Lab, Advanced Robotics Centre, National University of Singapore, Singapore
- Department of Biomedical Engineering, National University of Singapore, Singapore
| | - Raye Chen-Hua Yeow
- Evolution Innovation Lab, Advanced Robotics Centre, National University of Singapore, Singapore
- Department of Biomedical Engineering, National University of Singapore, Singapore
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123
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Kang I, Molinaro DD, Choi G, Camargo J, Young AJ. Subject-Independent Continuous Locomotion Mode Classification for Robotic Hip Exoskeleton Applications. IEEE Trans Biomed Eng 2022; 69:3234-3242. [PMID: 35389859 DOI: 10.1109/tbme.2022.3165547] [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: 11/10/2022]
Abstract
Autonomous lower-limb exoskeletons must modulate assistance based on locomotion mode (e.g., ramp or stair ascent) to adapt to the corresponding changes in human biological joint dynamics. However, current mode classification strategies for exoskeletons often require user-specific tuning, have a slow update rate, and rely on additional sensors outside of the exoskeleton sensor suite. In this study, we introduce a deep convolutional neural network-based locomotion mode classifier for hip exoskeleton applications using an open-source gait biomechanics dataset with various wearable sensors. Our approach removed the limitations of previous systems as it is 1) subject-independent (i.e., no user-specific data), 2) capable of continuously classifying for smooth and seamless mode transitions, and 3) only utilizes minimal wearable sensors native to a conventional hip exoskeleton. We optimized our model, based on several important factors contributing to overall performance, such as transition label timing, model architecture, and sensor placement, which provides a holistic understanding of mode classifier design. Our optimized DL model showed a 3.13% classification error (steady-state: 0.80 ± 0.38% and transitional: 6.49 ± 1.42%), outperforming other machine learning-based benchmarks commonly practiced in the field (p<0.05). Furthermore, our multi-modal analysis indicated that our model can maintain high performance in different settings such as to unseen slopes on stairs or ramps. Thus, our study presents a novel locomotion mode framework, capable of advancing robotic exoskeleton applications towards assisting community ambulation.
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124
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Shetty VS, Lee UH, Ingraham KA, Rouse EJ. A Data Driven Approach for Predicting Preferred Ankle Stiffness of a Quasi-Passive Prosthesis. IEEE Robot Autom Lett 2022. [DOI: 10.1109/lra.2022.3144790] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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125
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Miskovic L, Dezman M, Petric T. Pneumatic Quasi-Passive Variable Stiffness Mechanism for Energy Storage Applications. IEEE Robot Autom Lett 2022. [DOI: 10.1109/lra.2022.3141211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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126
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Li K, Tucker M, Gehlhar R, Yue Y, Ames AD. Natural Multicontact Walking for Robotic Assistive Devices via Musculoskeletal Models and Hybrid Zero Dynamics. IEEE Robot Autom Lett 2022. [DOI: 10.1109/lra.2022.3149568] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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127
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Zhong B, Guo K, Yu H, Zhang M. Toward Gait Symmetry Enhancement via a Cable-Driven Exoskeleton Powered by Series Elastic Actuators. IEEE Robot Autom Lett 2022. [DOI: 10.1109/lra.2021.3130639] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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128
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Liu W, Zhong J, Wu R, Fylstra BL, Si J, Huang HH. Inferring Human-Robot Performance Objectives During Locomotion Using Inverse Reinforcement Learning and Inverse Optimal Control. IEEE Robot Autom Lett 2022. [DOI: 10.1109/lra.2022.3143579] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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129
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130
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Matsiko A. Robotic assistive technologies get more personal. Sci Robot 2022; 7:eabo5528. [PMID: 35353600 DOI: 10.1126/scirobotics.abo5528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Personalized and adaptive control systems can improve the efficacy of assistive technologies in rehabilitation.
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Affiliation(s)
- Amos Matsiko
- Amos Matsiko is a Senior Editor at Science Robotics.
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131
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Ingraham KA, Remy CD, Rouse EJ. The role of user preference in the customized control of robotic exoskeletons. Sci Robot 2022; 7:eabj3487. [PMID: 35353602 DOI: 10.1126/scirobotics.abj3487] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
User preference is a promising objective for the control of robotic exoskeletons because it may capture the multifactorial nature of exoskeleton use. However, to use it, we must first understand its characteristics in the context of exoskeleton control. Here, we systematically measured the control preferences of individuals wearing bilateral ankle exoskeletons during walking. We investigated users' repeatability identifying their preferences and how preference changes with walking speed, device exposure, and between individuals with different technical backgrounds. Twelve naive and 12 knowledgeable nondisabled participants identified their preferred assistance in repeated trials by simultaneously self-tuning the magnitude and timing of peak torque. They were blinded to the control parameters and relied solely on their perception of the assistance to guide their tuning. We found that participants' preferences ranged from 7.9 to 19.4 newton-meters and 54.1 to 59.2 percent of the gait cycle. Across trials, participants repeatably identified their preferences with a mean standard deviation of 1.7 newton-meters and 1.5 percent of the gait cycle. Within a trial, participants converged on their preference in 105 seconds. As the experiment progressed, naive users preferred higher torque magnitude. At faster walking speeds, these individuals were more precise at identifying the magnitude of their preferred assistance. Knowledgeable users preferred higher torque than naive users. These results highlight that although preference is a dynamic quantity, individuals can reliably identify their preferences. This work motivates strategies for the control of lower limb exoskeletons in which individuals customize assistance according to their unique preferences and provides meaningful insight into how users interact with exoskeletons.
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Affiliation(s)
- K A Ingraham
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, USA.,Robotics Institute, University of Michigan, Ann Arbor, MI, USA
| | - C D Remy
- Institute for Nonlinear Mechanics, University of Stuttgart, Stuttgart, Germany
| | - E J Rouse
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, USA.,Robotics Institute, University of Michigan, Ann Arbor, MI, USA
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132
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Peng X, Acosta-Sojo Y, Wu MI, Stirling L. Actuation Timing Perception of a Powered Ankle Exoskeleton and its Associated Ankle Angle Changes During Walking. IEEE Trans Neural Syst Rehabil Eng 2022; 30:869-877. [PMID: 35333715 DOI: 10.1109/tnsre.2022.3162213] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Robotic ankle exoskeletons have the potential to extend human ability, and actuation timing serves as one of the critical parameters in its controller design. While many experiments have investigated the optimal actuation timing values to achieve different objective functions (e.g. minimizing metabolic cost), studies on users' perception of control parameters are gaining interest as it gives information on people's comfort, coordination, and trust in using devices, as well as providing foundations on how the sensorimotor system detects the exoskeleton behavior changes. The purpose of this study was to evaluate people's sensitivity to changes in exoskeleton actuation timing and its associated exoskeleton ankle angle changes during walking. Participants (n=15) with little or no prior experience with ankle exoskeletons were recruited and performed a psychophysical experiment to characterize their just-noticeable difference (JND) thresholds for actuation timing. Participants wore a bilateral active ankle exoskeleton and compared pairs of torque profiles with different actuation timings and low peak torque (0.225 Nm/kg) while walking on the treadmill. The mean timing JND across participants was 2.8±0.6% stride period. Individuals exhibited different sensitivity towards actuation timing, and their associated exoskeleton ankle angle changes also varied. The variance in ankle angle changes might be explained by their differences in ankle stiffness and different ankle torques provided during walking. The results provide insights into how people perceive the changes in exoskeleton control parameters and show individual differences in exoskeleton usage. The actuation timing JND found in this study can also help determine the necessary controller precision.
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133
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Lee IC, Fylstra BL, Liu M, Lenzi T, Huang H. Is there a trade-off between economy and task goal variability in transfemoral amputee gait? J Neuroeng Rehabil 2022; 19:29. [PMID: 35300696 PMCID: PMC8932056 DOI: 10.1186/s12984-022-01004-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 02/22/2022] [Indexed: 11/11/2022] Open
Abstract
BACKGROUND Energy cost minimization has been widely accepted to regulate gait. Optimization principles have been frequently used to explain how individuals adapt their gait pattern. However, there have been rare attempts to account for the role of variability in this optimization process. Motor redundancy can enable individuals to perform tasks reliably while achieving energy optimization. However, we do not know how the non-goal-equivalent and goal-equivalent variability is regulated. In this study, we investigated how unilateral transfemoral amputees regulate step and stride variability based on the task to achieve energy economy. METHODS Nine individuals with unilateral transfemoral amputation walked on a treadmill at speeds of 0.6, 0.8, 1.0, 1.2 and 1.4 m/s using their prescribed passive prostheses. We calculated the step-to-step and stride-to-stride variability and applied goal equivalent manifold (GEM) based control to decompose goal-equivalent and non-goal-equivalent manifold. To quantify the energy economy, the energy recovery rate (R) was calculated based on potential energy and kinetic energy. Comparisons were made between GEM variabilities and commonly used standard deviation measurements. A linear regression model was used to investigate the trade-off between R and GEM variabilities. RESULTS Our analysis shows greater variability along the goal-equivalent manifold compared to the non-goal-equivalent manifold (p < 0.001). Moreover, our analysis shows lower energy recovery rate for amputee gait compared to nonamputee gait (at least 20% less at faster walking speed). We found a negative relationship between energy recovery rate and non-goal-equivalent variability. Compared to the standard deviation measurements, the variability decomposed using GEM reflected the preferred walking speed and the limitation of the passive prosthetic device. CONCLUSION Individuals with amputation cleverly leverage task redundancy, regulating step and stride variability to the GEM. This result suggests that task redundancy enables unilateral amputees to benefit from motor variability in terms of energy economy. The differences observed between prosthetic step and intact step support the development of prosthetic limbs capable of enhancing positive work during the double support phase and of powered prosthesis controllers that allow for variability along the task space while minimizing variability that interferes with the task goal. This study provides a different perspective on amputee gait analysis and challenges the field to think differently about the role of variability.
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Affiliation(s)
- I-Chieh Lee
- Joint Department of Biomedical Engineering, North Carolina State University and University of North Carolina at Chapel Hill, Raleigh, NC, 27606, USA.
| | - Bretta L Fylstra
- Joint Department of Biomedical Engineering, North Carolina State University and University of North Carolina at Chapel Hill, Raleigh, NC, 27606, USA
| | - Ming Liu
- Joint Department of Biomedical Engineering, North Carolina State University and University of North Carolina at Chapel Hill, Raleigh, NC, 27606, USA
| | - Tommaso Lenzi
- Department of Mechanical Engineering and Robotics Center, The University of Utah, Salt Lake City, UT, USA
| | - He Huang
- Joint Department of Biomedical Engineering, North Carolina State University and University of North Carolina at Chapel Hill, Raleigh, NC, 27606, USA
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134
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Antonellis P, Mohammadzadeh Gonabadi A, Myers SA, Pipinos II, Malcolm P. Metabolically efficient walking assistance using optimized timed forces at the waist. Sci Robot 2022; 7:eabh1925. [PMID: 35294219 DOI: 10.1126/scirobotics.abh1925] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The metabolic rate of walking can be reduced by applying a constant forward force at the center of mass. It has been shown that the metabolically optimal constant force magnitude minimizes propulsion ground reaction force at the expense of increased braking. This led to the hypothesis that selectively assisting propulsion could lead to greater benefits. We used a robotic waist tether to evaluate the effects of forward forces with different timings and magnitudes. Here, we show that it is possible to reduce the metabolic rate of healthy participants by 48% with a greater efficiency ratio of metabolic cost reduction per unit of net aiding work compared with other assistive robots. This result was obtained using a sinusoidal force profile with peak timing during the middle of the double support. The same timing could also reduce the metabolic rate in patients with peripheral artery disease. A model explains that the optimal force profile accelerates the center of mass into the inverted pendulum movement during single support. Contrary to the hypothesis, the optimal force timing did not entirely coincide with propulsion. Within the field of wearable robotics, there is a trend to use devices to mimic biological torque or force profiles. Such bioinspired actuation can have relevant benefits; however, our results demonstrate that this is not necessarily optimal for reducing metabolic rate.
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Affiliation(s)
- Prokopios Antonellis
- Department of Biomechanics and Center for Research in Human Movement Variability, University of Nebraska at Omaha, 6160 University Drive South, Omaha, NE 68182, USA.,Department of Neurology, School of Medicine, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, OP-32, Portland, OR 97239, USA
| | - Arash Mohammadzadeh Gonabadi
- Department of Biomechanics and Center for Research in Human Movement Variability, University of Nebraska at Omaha, 6160 University Drive South, Omaha, NE 68182, USA.,Rehabilitation Engineering Center, Institute for Rehabilitation Science and Engineering, Madonna Rehabilitation Hospital, 5401 South Street, Lincoln, NE 68506, USA
| | - Sara A Myers
- Department of Biomechanics and Center for Research in Human Movement Variability, University of Nebraska at Omaha, 6160 University Drive South, Omaha, NE 68182, USA.,Department of Surgery and Research Service, Veterans Affairs Nebraska-Western Iowa Medical Center, Omaha, NE 68105, USA
| | - Iraklis I Pipinos
- Department of Surgery and Research Service, Veterans Affairs Nebraska-Western Iowa Medical Center, Omaha, NE 68105, USA.,Department of Surgery, University of Nebraska Medical Center, 982500 Nebraska Medical Center, Omaha, NE 68198, USA
| | - Philippe Malcolm
- Department of Biomechanics and Center for Research in Human Movement Variability, University of Nebraska at Omaha, 6160 University Drive South, Omaha, NE 68182, USA
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135
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De Bock S, Rossini M, Lefeber D, Rodriguez-Guerrero C, Geeroms J, Meeusen R, De Pauw K. An Occupational Shoulder Exoskeleton Reduces Muscle Activity and Fatigue During Overhead Work. IEEE Trans Biomed Eng 2022; 69:3008-3020. [PMID: 35290183 DOI: 10.1109/tbme.2022.3159094] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Objective. This paper assesses the effect of a passive shoulder exoskeleton prototype, Exo4Work, on muscle activity, muscle fatigue and subjective experience during simulated occupational overhead and non-overhead work. Methods. Twenty-two healthy males performed six simulated industrial tasks with and without Exo4Work exoskeleton in a randomized counterbalanced cross-over design. During these tasks electromyography, heart rate, metabolic cost, subjective parameters and performance parameters were acquired. The effect of the exoskeleton and the body side on these parameters was investigated. Results. Anterior deltoid activity and fatigue reduced up to 16% and 41%, respectively, during isometric overhead work, and minimized hindrance of the device during non-overhead tasks. Wearing the exoskeleton increased feelings of frustration and increased discomfort in the areas where the exoskeleton and the body interfaced. The assistive effect of the exoskeleton was less prominent during dynamic tasks. Conclusion. This exoskeleton may reduce muscle activity and delay development of muscle fatigue in an overhead working scenario. For dynamic applications, the exoskeleton's assistive profile, which mimics the gravitational torque of the arm, is potentially sub-optimal. Significance. This evaluation paper is the first to report reduced muscle fatigue and activity when working with an occupational shoulder exoskeleton providing one third of the gravitational torque of the arm during overhead work. These results stress the potential of occupational shoulder exoskeletons in overhead working situations and may direct towards longitudinal field experiments. Additionally, this experiment may stimulate future work to further investigate the effect of different assistive profiles.
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136
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Eden J, Bräcklein M, Ibáñez J, Barsakcioglu DY, Di Pino G, Farina D, Burdet E, Mehring C. Principles of human movement augmentation and the challenges in making it a reality. Nat Commun 2022; 13:1345. [PMID: 35292665 PMCID: PMC8924218 DOI: 10.1038/s41467-022-28725-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2021] [Accepted: 02/04/2022] [Indexed: 12/23/2022] Open
Abstract
Augmenting the body with artificial limbs controlled concurrently to one's natural limbs has long appeared in science fiction, but recent technological and neuroscientific advances have begun to make this possible. By allowing individuals to achieve otherwise impossible actions, movement augmentation could revolutionize medical and industrial applications and profoundly change the way humans interact with the environment. Here, we construct a movement augmentation taxonomy through what is augmented and how it is achieved. With this framework, we analyze augmentation that extends the number of degrees-of-freedom, discuss critical features of effective augmentation such as physiological control signals, sensory feedback and learning as well as application scenarios, and propose a vision for the field.
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Affiliation(s)
- Jonathan Eden
- Department of Bioengineering, Imperial College of Science, Technology and Medicine, London, UK
| | - Mario Bräcklein
- Department of Bioengineering, Imperial College of Science, Technology and Medicine, London, UK
| | - Jaime Ibáñez
- Department of Bioengineering, Imperial College of Science, Technology and Medicine, London, UK
- BSICoS, IIS Aragón, Universidad de Zaragoza, Zaragoza, Spain
- Department of Clinical and Movement Neurosciences, Institute of Neurology, University College London, London, UK
| | | | - Giovanni Di Pino
- NEXT: Neurophysiology and Neuroengineering of Human-Technology Interaction Research Unit, Università Campus Bio-Medico di Roma, Rome, Italy
| | - Dario Farina
- Department of Bioengineering, Imperial College of Science, Technology and Medicine, London, UK
| | - Etienne Burdet
- Department of Bioengineering, Imperial College of Science, Technology and Medicine, London, UK.
| | - Carsten Mehring
- Bernstein Center Freiburg, University of Freiburg, Freiburg im Breisgau, 79104, Germany
- Faculty of Biology, University of Freiburg, Freiburg im Breisgau, 79104, Germany
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137
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Application of Wearable Sensors in Actuation and Control of Powered Ankle Exoskeletons: A Comprehensive Review. SENSORS 2022; 22:s22062244. [PMID: 35336413 PMCID: PMC8954890 DOI: 10.3390/s22062244] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 02/28/2022] [Accepted: 03/08/2022] [Indexed: 02/06/2023]
Abstract
Powered ankle exoskeletons (PAEs) are robotic devices developed for gait assistance, rehabilitation, and augmentation. To fulfil their purposes, PAEs vastly rely heavily on their sensor systems. Human–machine interface sensors collect the biomechanical signals from the human user to inform the higher level of the control hierarchy about the user’s locomotion intention and requirement, whereas machine–machine interface sensors monitor the output of the actuation unit to ensure precise tracking of the high-level control commands via the low-level control scheme. The current article aims to provide a comprehensive review of how wearable sensor technology has contributed to the actuation and control of the PAEs developed over the past two decades. The control schemes and actuation principles employed in the reviewed PAEs, as well as their interaction with the integrated sensor systems, are investigated in this review. Further, the role of wearable sensors in overcoming the main challenges in developing fully autonomous portable PAEs is discussed. Finally, a brief discussion on how the recent technology advancements in wearable sensors, including environment—machine interface sensors, could promote the future generation of fully autonomous portable PAEs is provided.
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138
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Lee J, Huber ME, Hogan N. Gait Entrainment to Torque Pulses from a Hip Exoskeleton Robot. IEEE Trans Neural Syst Rehabil Eng 2022; 30:656-667. [PMID: 35286261 DOI: 10.1109/tnsre.2022.3155770] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Robot-aided locomotor rehabilitation has proven challenging. To facilitate progress, it is important to first understand the neuro-mechanical dynamics and control of unimpaired human locomotion. Our previous studies found that human gait entrained to periodic torque pulses at the ankle when the pulse period was close to preferred stride duration. Moreover, synchronized gait exhibited constant phase relation with the pulses so that the robot provided mechanical assistance. To test the generality of mechanical gait entrainment, this study characterized unimpaired human subjects' responses to periodic torque pulses during overground walking. The intervention was applied by a hip exoskeleton robot, Samsung GEMS-H. Gait entrainment was assessed based on the time-course of the phase at which torque pulses occurred within each stride. Experiments were conducted for two consecutive days to evaluate whether the second day elicited more entrainment. Whether entrainment was affected by the difference between pulse period and preferred stride duration was also assessed. Results indicated that the intervention evoked gait entrainment that occurred more often when the period of perturbation was closer to subjects' preferred stride duration, but the difference between consecutive days was insignificant. Entrainment was accompanied by convergence of pulse phase to a similar value across all conditions, where the robot maximized mechanical assistance. Clear evidence of motor adaptation indicated the potential of the intervention for rehabilitation. This study quantified important aspects of the nonlinear neuro-mechanical dynamics underlying unimpaired human walking, which will inform the development of effective approaches to robot-aided locomotor rehabilitation, exploiting natural dynamics in a minimally-encumbering way.
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139
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Visual guidance can help with the use of a robotic exoskeleton during human walking. Sci Rep 2022; 12:3881. [PMID: 35273244 PMCID: PMC8913727 DOI: 10.1038/s41598-022-07736-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Accepted: 02/15/2022] [Indexed: 11/29/2022] Open
Abstract
Walking is an important activity that supports the health-related quality of life, and for those who need assistance, robotic devices are available to help. Recent progress in wearable robots has identified the importance of customizing the assistance provided by the robot to the individual, resulting in robot adaptation to the human. However, current implementations minimize the role of human adaptation to the robot, for example, by the users modifying their movements based on the provided robot assistance. This study investigated the effect of visual feedback to guide the users in adapting their movements in response to wearable robot assistance. The visual feedback helped the users reduce their metabolic cost of walking without any changes in robot assistance in a given time. In a case with the initially metabolic expensive (IMExp) exoskeleton condition, both training methods helped reduce the metabolic cost of walking. The results suggest that visual feedback training is helpful to use the exoskeleton for various conditions. Without feedback, the training is helpful only for the IMExp exoskeleton condition. This result suggests visual feedback training can be useful to facilitate the use of non-personalized, generic assistance, where the assistance is not tuned for each user, in a relatively short time.
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140
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Medrano RL, Thomas GC, Rouse EJ. Can humans perceive the metabolic benefit provided by augmentative exoskeletons? J Neuroeng Rehabil 2022; 19:26. [PMID: 35219335 PMCID: PMC8881941 DOI: 10.1186/s12984-022-01002-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Accepted: 02/15/2022] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND The purpose of augmentative exoskeletons is to help people exceed the limitations of their human bodies, but this cannot be realized unless people choose to use these exciting technologies. Although human walking efficiency has been highly optimized over generations, exoskeletons have been able to consistently improve this efficiency by 10-15%. However, despite these measurable improvements, exoskeletons today remain confined to the laboratory. To achieve widespread adoption, exoskeletons must not only exceed the efficiency of human walking, but also provide a perceivable benefit to their wearers. METHODS In this study, we quantify the perceptual threshold of the metabolic efficiency benefit provided during exoskeleton-assisted locomotion. Ten participants wore bilateral ankle exoskeletons during continuous walking. The assistance provided by the exoskeletons was varied in 2 min intervals while participants provided feedback on their metabolic rate. These data were aggregated and used to estimate the perceptual threshold. RESULTS Participants were able to detect a change in their metabolic rate of 22.7% (SD: 17.0%) with 75% accuracy. This indicates that in the short term and on average, wearers cannot yet reliably perceive the metabolic benefits of today's augmentative exoskeletons. CONCLUSIONS If wearers cannot perceive the benefits provided by these technologies, it will negatively affect their impact, including long-term adoption and product viability. Future exoskeleton researchers and designers can use these methods and results to inform the development of exoskeletons that reach their potential.
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Affiliation(s)
- Roberto Leo Medrano
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, 48109 USA
- Robotics Institute, University of Michigan, 48109 Ann Arbor, USA
| | - Gray Cortright Thomas
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, 48109 USA
- Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, 48109 USA
- Robotics Institute, University of Michigan, 48109 Ann Arbor, USA
| | - Elliott J. Rouse
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, 48109 USA
- Robotics Institute, University of Michigan, 48109 Ann Arbor, USA
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141
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Bayón C, Keemink AQL, van Mierlo M, Rampeltshammer W, van der Kooij H, van Asseldonk EHF. Cooperative ankle-exoskeleton control can reduce effort to recover balance after unexpected disturbances during walking. J Neuroeng Rehabil 2022; 19:21. [PMID: 35172846 PMCID: PMC8851842 DOI: 10.1186/s12984-022-01000-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 02/02/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND In the last two decades, lower-limb exoskeletons have been developed to assist human standing and locomotion. One of the ongoing challenges is the cooperation between the exoskeleton balance support and the wearer control. Here we present a cooperative ankle-exoskeleton control strategy to assist in balance recovery after unexpected disturbances during walking, which is inspired on human balance responses. METHODS We evaluated the novel controller in ten able-bodied participants wearing the ankle modules of the Symbitron exoskeleton. During walking, participants received unexpected forward pushes with different timing and magnitude at the pelvis level, while being supported (Exo-Assistance) or not (Exo-NoAssistance) by the robotic assistance provided by the controller. The effectiveness of the assistive strategy was assessed in terms of (1) controller performance (Detection Delay, Joint Angles, and Exerted Ankle Torques), (2) analysis of effort (integral of normalized Muscle Activity after perturbation onset); and (3) Analysis of center of mass COM kinematics (relative maximum COM Motion, Recovery Time and Margin of Stability) and spatio-temporal parameters (Step Length and Swing Time). RESULTS In general, the results show that when the controller was active, it was able to reduce participants' effort while keeping similar ability to counteract and withstand the balance disturbances. Significant reductions were found for soleus and gastrocnemius medialis activity of the stance leg when comparing Exo-Assistance and Exo-NoAssistance walking conditions. CONCLUSIONS The proposed controller was able to cooperate with the able-bodied participants in counteracting perturbations, contributing to the state-of-the-art of bio-inspired cooperative ankle exoskeleton controllers for supporting dynamic balance. In the future, this control strategy may be used in exoskeletons to support and improve balance control in users with motor disabilities.
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Affiliation(s)
- Cristina Bayón
- Department of Biomechanical Engineering, University of Twente, Enschede, The Netherlands
| | - Arvid Q. L. Keemink
- Department of Biomechanical Engineering, University of Twente, Enschede, The Netherlands
| | - Michelle van Mierlo
- Department of Biomechanical Engineering, University of Twente, Enschede, The Netherlands
| | | | - Herman van der Kooij
- Department of Biomechanical Engineering, University of Twente, Enschede, The Netherlands
- Department of BioMechanical Engineering, Delft University of Technology, Delft, The Netherlands
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142
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Tomc M, Matjačić Z. Harnessing Energy of a Treadmill for Push-Off Assistance During Walking: In-Silico Feasibility Study. Front Bioeng Biotechnol 2022; 10:832087. [PMID: 35252141 PMCID: PMC8889039 DOI: 10.3389/fbioe.2022.832087] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Accepted: 01/31/2022] [Indexed: 11/13/2022] Open
Abstract
Regaining efficient push-off is a crucial step in restitution of walking ability in impaired individuals. Inspired by the elastic nature of ankle plantarflexor muscle-tendon complex, we propose a novel rehabilitation device: Ankle Exoskeleton using Treadmill Actuation for Push-off assistance (AN-EXTRA-Push). Using a brake and an elastic tendon, it harnesses energy of a moving treadmill during stance phase, then releases it during push-off to aid with plantarflexion torque generation. We studied the feasibility of such a device and explored some key design and control parameters. A parameter sweep of three key parameters (brake engagement timing, brake disengagement timing and elastic tendon stiffness) was conducted in-silico. Results suggest that such a device is feasible and might inherently possess some features that simplify its control. Brake engagement timing and elastic tendon stiffness values determine the level of exoskeleton assistance. Our study affirms that timing of assistive torque is crucial, especially the timing of assistance termination which is determined by brake disengagement timing. Insights acquired by this study should serve as a basis for designing an experimental device and conducting studies on effects of AN-EXTRA-Push in humans.
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Affiliation(s)
- Matej Tomc
- Research and Development Unit, University Rehabilitation Institute Republic of Slovenia, Ljubljana, Slovenia
- Laboratory of Robotics, Faculty of Electrical Engineering, University of Ljubljana, Ljubljana, Slovenia
- *Correspondence: Matej Tomc,
| | - Zlatko Matjačić
- Research and Development Unit, University Rehabilitation Institute Republic of Slovenia, Ljubljana, Slovenia
- Laboratory of Robotics, Faculty of Electrical Engineering, University of Ljubljana, Ljubljana, Slovenia
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143
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Abstract
Summary
The knee joint plays a significant role in ground clearness, which is a crucial subtask of normal walking and avoiding falls. While post-stroke survivors are often faced with muscle weakness during walking, which leads to inadequate knee flexion. The lack of ground clearance caused by inadequate knee flexion will severely impede walking, increase metabolic exertion, and increase the risk of falls. A compliant exoskeleton robot possesses more favorable edges than other rigid ones in lightweight, safety, sense of comfort, and so on. We developed a new type of soft exoskeleton robot to assist the knee joint to achieve desired movements with Bowden cable transmitting force and torque. With the agonist–antagonist driving method, like a group of muscles working, we have explored dual-motors structure to realize the knee flexion function. It has built a standard dynamic model to analyze stability and realize the control law. We have conducted simulation and prototype experiments to verify the feasibility and usefulness of our method. The results show that the device can compensate for the lack of the knee joint driving force and realize the reference movement. Finally, we concluded that our method is a desirable way, and the scheme could improve the knee flexion ability and clearing ground.
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144
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Kao PC, Pierro MA. Motor adaptation to cognitive challenges and walking perturbations in healthy young adults. Gait Posture 2022; 92:167-175. [PMID: 34856525 DOI: 10.1016/j.gaitpost.2021.11.030] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2021] [Revised: 11/13/2021] [Accepted: 11/22/2021] [Indexed: 02/02/2023]
Abstract
BACKGROUND Cognitive-walking interference is manifested when simultaneously performing a cognitive task while walking. However, majority of the dual-task walking paradigms incorporated relatively short testing trials and were focused on posing a cognitive challenge by adding a secondary cognitive task but not introducing walking perturbations. RESEARCH QUESTION How do healthy young adults adapt to concurrent cognitive challenges and walking perturbations in terms of task prioritization and adaptation strategies to control walking stability? METHODS Eighteen healthy young participants walked with and without (1) continuous treadmill platform sways (Perturbed and Unperturbed walking), and (2) performing one of the cognitive tasks: visual and auditory Stroop tasks, Clock task, Paced Auditory Serial Addition Test (PASAT), and walk only. Primary outcome measures included cognitive task performance, mediolateral dynamic margins of stability (MOSML), M-L local dynamic stability, stride time variability and the dual-task interference (DTI) on these measures. RESULTS Gait adjustments made during Perturbed walking did not improve walking stability but instead, showing more local instability and greater gait variability (all p < 0.001) than Unperturbed walking. Participants increased average MOSML during Clock and PASAT compared to Walk Only for both Perturbed and Unperturbed walking (THSD, p < 0.05). Participants had significantly less DTI on stride time variability during Unperturbed walking than during Perturbed walking (p < 0.001). Participants also had significantly greater DTI on PASAT performance during Perturbed than during Unperturbed walking (THSD, p < 0.05) SIGNIFICANCE: Participants prioritized the walking task under a more challenging walking condition although the adjustments made during Perturbed walking were not sufficient to maintain a similar level of walking stability as Unperturbed walking. Adjustments to the cognitive-walking challenges were differed by the type of cognitive tasks. The current findings suggest that cognitive tasks involving both working memory and information processing or visuospatial recognition or attention have greater impact on gait especially during the perturbed walking condition.
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Affiliation(s)
- Pei-Chun Kao
- Department of Physical Therapy and Kinesiology, University of Massachusetts Lowell, Lowell, MA, United States; New England Robotics Validation and Experimentation (NERVE) Center, University of Massachusetts Lowell, Lowell, MA, United States.
| | - Michaela A Pierro
- Biomedical Engineering and Biotechnology Program, University of Massachusetts Lowell, Lowell, MA, United States; Delsys Inc., Natick, MA, United States
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145
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Waterval NFJ, Brehm MA, Harlaar J, Nollet F. Energy cost optimized dorsal leaf ankle-foot-orthoses reduce impact forces on the contralateral leg in people with unilateral plantar flexor weakness. Gait Posture 2022; 92:71-76. [PMID: 34826696 DOI: 10.1016/j.gaitpost.2021.11.023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 11/09/2021] [Accepted: 11/16/2021] [Indexed: 02/02/2023]
Abstract
BACKGROUND In individuals with unilateral plantar flexor weakness, the second peak of the vertical ground reaction force (GRF) is decreased. This leads to a higher ground reaction force, e.g. impact, of the contralateral leg, potentially explaining quadriceps muscle and/or knee joint pain. Energy cost optimized dorsal leaf ankle-foot-orthoses (AFOs) may increase the push-off ground reaction force, which in turn could lead to lower impact forces on the contralateral leg. RESEARCH QUESTIONS 1) Are impact forces increased in the contralateral leg of people with unilateral plantar flexor weakness compared to healthy subjects? 2) Do energy cost optimized AFOs reduce impact forces and improve leg impact symmetry compared to walking without AFO in people with unilateral plantar flexor weakness? METHODS Nine subjects with unilateral plantar flexor weakness were provided a dorsal leaf AFO with a stiffness primarily optimized for energy cost. Using 3D gait analyses peak vertical GRF during loading response with and without AFO, and the symmetry between the legs in peak GRF were calculated. Peak GRF and symmetry were compared with reference data of 23 healthy subjects. RESULTS The contralateral leg showed a significant higher peak vertical GRF (12.0 ± 0.9 vs 11.2 ± 0.6 N/kg, p = 0.005) compared to healthy reference data. When walking with AFO, the peak vertical GRF of the contralateral leg significantly reduced (from 12.0 ± 0.9 to 11.4 ± 0.7 N/kg, p = 0.017) and symmetry improved compared to no AFO (from 0.93 ± 0.06 to 1.01 ± 0.05, p < 0.001). CONCLUSION In subjects with unilateral plantar flexor weakness, impact force on the contralateral leg was increased when compared to healthy subjects and dorsal leaf AFOs optimized for energy cost substantially reduced this force and improved impact symmetry when compared to walking without AFO. This indicates that dorsal leaf AFOs may reduce pain resulting from increased impact forces during gait in the contralateral leg in people with unilateral plantar flexor weakness.
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Affiliation(s)
- N F J Waterval
- Amsterdam UMC, University of Amsterdam, Rehabilitation Medicine, Amsterdam Movement Sciences, Meibergdreef 9, Amsterdam, The Netherlands.
| | - M A Brehm
- Amsterdam UMC, University of Amsterdam, Rehabilitation Medicine, Amsterdam Movement Sciences, Meibergdreef 9, Amsterdam, The Netherlands
| | - J Harlaar
- Department of Biomechanical Engineering, Delft University of Technology, Delft, The Netherlands; Department of Orthopaedics, Erasmus Medical Center, Rotterdam, Netherlands
| | - F Nollet
- Amsterdam UMC, University of Amsterdam, Rehabilitation Medicine, Amsterdam Movement Sciences, Meibergdreef 9, Amsterdam, The Netherlands
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146
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Febrer-Nafría M, Fregly BJ, Font-Llagunes JM. Evaluation of Optimal Control Approaches for Predicting Active Knee-Ankle-Foot-Orthosis Motion for Individuals With Spinal Cord Injury. Front Neurorobot 2022; 15:748148. [PMID: 35140596 PMCID: PMC8818856 DOI: 10.3389/fnbot.2021.748148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Accepted: 12/08/2021] [Indexed: 11/13/2022] Open
Abstract
Gait restoration of individuals with spinal cord injury can be partially achieved using active orthoses or exoskeletons. To improve the walking ability of each patient as much as possible, it is important to personalize the parameters that define the device actuation. This study investigates whether using an optimal control-based predictive simulation approach to personalize pre-defined knee trajectory parameters for an active knee-ankle-foot orthosis (KAFO) used by spinal cord injured (SCI) subjects could potentially be an alternative to the current trial-and-error approach. We aimed to find the knee angle trajectory that produced an improved orthosis-assisted gait pattern compared to the one with passive support (locked knee). We collected experimental data from a healthy subject assisted by crutches and KAFOs (with locked knee and with knee flexion assistance) and from an SCI subject assisted by crutches and KAFOs (with locked knee). First, we compared different cost functions and chose the one that produced results closest to experimental locked knee walking for the healthy subject (angular coordinates mean RMSE was 5.74°). For this subject, we predicted crutch-orthosis-assisted walking imposing a pre-defined knee angle trajectory for different maximum knee flexion parameter values, and results were evaluated against experimental data using that same pre-defined knee flexion trajectories in the real device. Finally, using the selected cost function, gait cycles for different knee flexion assistance were predicted for an SCI subject. We evaluated changes in four clinically relevant parameters: foot clearance, stride length, cadence, and hip flexion ROM. Simulations for different values of maximum knee flexion showed variations of these parameters that were consistent with experimental data for the healthy subject (e.g., foot clearance increased/decreased similarly in experimental and predicted motions) and were reasonable for the SCI subject (e.g., maximum parameter values were found for moderate knee flexion). Although more research is needed before this method can be applied to choose optimal active orthosis controller parameters for specific subjects, these findings suggest that optimal control prediction of crutch-orthosis-assisted walking using biomechanical models might be used in place of the trial-and-error method to select the best maximum knee flexion angle during gait for a specific SCI subject.
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Affiliation(s)
- Míriam Febrer-Nafría
- Biomechanical Engineering Lab, Department of Mechanical Engineering and Research Centre for Biomedical Engineering, Universitat Politècnica de Catalunya, Barcelona, Spain
- Health Technologies and Innovation, Institut de Recerca Sant Joan de Déu, Esplugues de Llobregat, Spain
| | - Benjamin J Fregly
- Deptartment of Mechanical Engineering, Rice University, Houston, TX, United States
| | - Josep M Font-Llagunes
- Biomechanical Engineering Lab, Department of Mechanical Engineering and Research Centre for Biomedical Engineering, Universitat Politècnica de Catalunya, Barcelona, Spain
- Health Technologies and Innovation, Institut de Recerca Sant Joan de Déu, Esplugues de Llobregat, Spain
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147
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A Portable Waist-Loaded Soft Exosuit for Hip Flexion Assistance with Running. MICROMACHINES 2022; 13:mi13020157. [PMID: 35208282 PMCID: PMC8874989 DOI: 10.3390/mi13020157] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 01/16/2022] [Accepted: 01/20/2022] [Indexed: 12/10/2022]
Abstract
The soft exosuit is an emerging robotics, which has been proven to considerably reduce the metabolic consumption of human walking and running. However, compared to walking, relatively few soft exosuits have been studied for running. Many soft exosuits used for running are worn on the back and with a heavy weight load, which may cause instability while running and potentially increase metabolic consumption. Therefore, reducing the weight of the whole soft exosuit system as much as possible and keeping the soft exosuit close to the center of gravity, may improve running stability and further reduce metabolic consumption. In this paper, a portable waist-loaded soft exosuit, the weight of which is almost entirely concentrated at the waist, is shown to assist hip flexion during running, and justifies choosing to assist hip flexion while running. As indicated by the experiments of motion flexibility, wearing the waist-loaded soft exosuit can assist in performing many common and complex motions. The metabolic consumption experiments proved that the portable waist-loaded soft exosuit reduces the metabolic consumption rate of wearers when jogging on the treadmill at 6 km per hour by 7.79% compared with locomotion without the exosuit. Additionally, at the running speed of 8 km per hour, using the waist-loaded soft exosuit can reduce metabolic consumption rate by 4.74%. Similarly, at the running speed of 10 km per hour, it also can be reduced by 6.12%. It is demonstrated that assisting hip flexion for running is also a reasonable method, and wearing the waist-loaded soft exosuit can keep human motion flexibility and reduce metabolic consumption.
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148
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Chang CH, Casas J, Brose SW, Duenas VH. Closed-Loop Torque and Kinematic Control of a Hybrid Lower-Limb Exoskeleton for Treadmill Walking. Front Robot AI 2022; 8:702860. [PMID: 35127833 PMCID: PMC8811381 DOI: 10.3389/frobt.2021.702860] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Accepted: 11/08/2021] [Indexed: 11/13/2022] Open
Abstract
Restoring and improving the ability to walk is a top priority for individuals with movement impairments due to neurological injuries. Powered exoskeletons coupled with functional electrical stimulation (FES), called hybrid exoskeletons, exploit the benefits of activating muscles and robotic assistance for locomotion. In this paper, a cable-driven lower-limb exoskeleton is integrated with FES for treadmill walking at a constant speed. A nonlinear robust controller is used to activate the quadriceps and hamstrings muscle groups via FES to achieve kinematic tracking about the knee joint. Moreover, electric motors adjust the knee joint stiffness throughout the gait cycle using an integral torque feedback controller. For the hip joint, a robust sliding-mode controller is developed to achieve kinematic tracking using electric motors. The human-exoskeleton dynamic model is derived using Lagrangian dynamics and incorporates phase-dependent switching to capture the effects of transitioning from the stance to the swing phase, and vice versa. Moreover, low-level control input switching is used to activate individual muscles and motors to achieve flexion and extension about the hip and knee joints. A Lyapunov-based stability analysis is developed to ensure exponential tracking of the kinematic and torque closed-loop error systems, while guaranteeing that the control input signals remain bounded. The developed controllers were tested in real-time walking experiments on a treadmill in three able-bodied individuals at two gait speeds. The experimental results demonstrate the feasibility of coupling a cable-driven exoskeleton with FES for treadmill walking using a switching-based control strategy and exploiting both kinematic and force feedback.
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Affiliation(s)
- Chen-Hao Chang
- Department of Mechanical and Aerospace Engineering, Syracuse University, Syracuse, NY, United States
| | - Jonathan Casas
- Department of Mechanical and Aerospace Engineering, Syracuse University, Syracuse, NY, United States
| | - Steven W. Brose
- Department of Physical Medicine and Rehabilitation, SUNY Upstate Medical University, Syracuse, NY, United States
- Spinal Cord Injury and Disabilities Service, Syracuse VA Medical Center, Syracuse, NY, United States
| | - Victor H. Duenas
- Department of Mechanical and Aerospace Engineering, Syracuse University, Syracuse, NY, United States
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149
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Wang W, Chen J, Ding J, Zhang J, Liu J. Improving Walking Economy With an Ankle Exoskeleton Prior to Human-in-the-Loop Optimization. Front Neurorobot 2022; 15:797147. [PMID: 35082609 PMCID: PMC8784531 DOI: 10.3389/fnbot.2021.797147] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 12/06/2021] [Indexed: 12/05/2022] Open
Abstract
Lower limb robotic exoskeletons have shown the capability to enhance human locomotion for healthy individuals or to assist motion rehabilitation and daily activities for patients. Recent advances in human-in-the-loop optimization that allowed for assistance customization have demonstrated great potential for performance improvement of exoskeletons. In the optimization process, subjects need to experience multiple types of assistance patterns, thus, leading to a long evaluation time. Besides, some patterns may be uncomfortable for the wearers, thereby resulting in unpleasant optimization experiences and inaccurate outcomes. In this study, we investigated the effectiveness of a series of ankle exoskeleton assistance patterns on improving walking economy prior to optimization. We conducted experiments to systematically evaluate the wearers' biomechanical and physiological responses to different assistance patterns on a lightweight cable-driven ankle exoskeleton during walking. We designed nine patterns in the optimization parameters range which varied peak torque magnitude and peak torque timing independently. Results showed that metabolic cost of walking was reduced by 17.1 ± 7.6% under one assistance pattern. Meanwhile, soleus (SOL) muscle activity was reduced by 40.9 ± 19.8% with that pattern. Exoskeleton assistance changed maximum ankle dorsiflexion and plantarflexion angle and reduced biological ankle moment. Assistance pattern with 48% peak torque timing and 0.75 N·m·kg−1 peak torque magnitude was effective in improving walking economy and can be selected as an initial pattern in the optimization procedure. Our results provided a preliminary understanding of how humans respond to different assistances and can be used to guide the initial assistance pattern selection in the optimization.
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Affiliation(s)
- Wei Wang
- College of Artificial Intelligence, Institute of Robotics and Automatic Information System, Nankai University, Tianjin, China
- Tianjin Key Laboratory of Intelligent Robotics, Nankai University, Tianjin, China
| | - Jianyu Chen
- College of Artificial Intelligence, Institute of Robotics and Automatic Information System, Nankai University, Tianjin, China
- Tianjin Key Laboratory of Intelligent Robotics, Nankai University, Tianjin, China
| | - Jianquan Ding
- College of Artificial Intelligence, Institute of Robotics and Automatic Information System, Nankai University, Tianjin, China
- Tianjin Key Laboratory of Intelligent Robotics, Nankai University, Tianjin, China
| | - Juanjuan Zhang
- College of Artificial Intelligence, Institute of Robotics and Automatic Information System, Nankai University, Tianjin, China
- Tianjin Key Laboratory of Intelligent Robotics, Nankai University, Tianjin, China
- *Correspondence: Juanjuan Zhang
| | - Jingtai Liu
- College of Artificial Intelligence, Institute of Robotics and Automatic Information System, Nankai University, Tianjin, China
- Tianjin Key Laboratory of Intelligent Robotics, Nankai University, Tianjin, China
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Coupled exoskeleton assistance simplifies control and maintains metabolic benefits: A simulation study. PLoS One 2022; 17:e0261318. [PMID: 34986191 PMCID: PMC8730392 DOI: 10.1371/journal.pone.0261318] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Accepted: 11/30/2021] [Indexed: 11/19/2022] Open
Abstract
Assistive exoskeletons can reduce the metabolic cost of walking, and recent advances in exoskeleton device design and control have resulted in large metabolic savings. Most exoskeleton devices provide assistance at either the ankle or hip. Exoskeletons that assist multiple joints have the potential to provide greater metabolic savings, but can require many actuators and complicated controllers, making it difficult to design effective assistance. Coupled assistance, when two or more joints are assisted using one actuator or control signal, could reduce control dimensionality while retaining metabolic benefits. However, it is unknown which combinations of assisted joints are most promising and if there are negative consequences associated with coupled assistance. Since designing assistance with human experiments is expensive and time-consuming, we used musculoskeletal simulation to evaluate metabolic savings from multi-joint assistance and identify promising joint combinations. We generated 2D muscle-driven simulations of walking while simultaneously optimizing control strategies for simulated lower-limb exoskeleton assistive devices to minimize metabolic cost. Each device provided assistance either at a single joint or at multiple joints using massless, ideal actuators. To assess if control could be simplified for multi-joint exoskeletons, we simulated different control strategies in which the torque provided at each joint was either controlled independently or coupled between joints. We compared the predicted optimal torque profiles and changes in muscle and total metabolic power consumption across the single joint and multi-joint assistance strategies. We found multi-joint devices-whether independent or coupled-provided 50% greater metabolic savings than single joint devices. The coupled multi-joint devices were able to achieve most of the metabolic savings produced by independently-controlled multi-joint devices. Our results indicate that device designers could simplify multi-joint exoskeleton designs by reducing the number of torque control parameters through coupling, while still maintaining large reductions in metabolic cost.
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