499 results on '"Herr, Hugh"'
Search Results
202. Design, Characterization, and Preliminary Assessment of a Two-Degree-of-Freedom Powered Ankle–Foot Prosthesis.
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Hsieh, Tsung-Han, Song, Hyungeun, Shu, Tony, Qiao, Junqing, Yeon, Seong Ho, Carney, Matthew, Mooney, Luke, Duval, Jean-François, and Herr, Hugh
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PROSTHETICS , *TORQUE control , *BRAIN-computer interfaces , *ROOT-mean-squares , *ANKLE , *PLANTARFLEXION - Abstract
Powered ankle prostheses have been proven to improve the walking economy of people with transtibial amputation. All commercial powered ankle prostheses that are currently available can only perform one-degree-of-freedom motion in a limited range. However, studies have shown that the frontal plane motion during ambulation is associated with balancing. In addition, as more advanced neural interfaces have become available for people with amputation, it is possible to fully recover ankle function by combining neural signals and a robotic ankle. Accordingly, there is a need for a powered ankle prosthesis that can have active control on not only plantarflexion and dorsiflexion but also eversion and inversion. We designed, built, and evaluated a two-degree-of-freedom (2-DoF) powered ankle–foot prosthesis that is untethered and can support level-ground walking. Benchtop tests were conducted to characterize the dynamics of the system. Walking trials were performed with a 77 kg subject that has unilateral transtibial amputation to evaluate system performance under realistic conditions. Benchtop tests demonstrated a step response rise time of less than 50 milliseconds for a torque of 40 N·m on each actuator. The closed-loop torque bandwidth of the actuator is 9.74 Hz. Walking trials demonstrated torque tracking errors (root mean square) of less than 7 N·m. These results suggested that the device can perform adequate torque control and support level-ground walking. This prosthesis can serve as a platform for studying biomechanics related to balance and has the possibility of further recovering the biological function of the ankle–subtalar–foot complex beyond the existing powered ankles. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
203. Accurate Heuristic Terrain Prediction in Powered Lower-Limb Prostheses Using Onboard Sensors.
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Stolyarov, Roman, Carney, Matthew, and Herr, Hugh
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ARTIFICIAL legs , *HEURISTIC , *ARTIFICIAL joints , *PROSTHETICS , *LEG amputation , *MACHINE learning , *RESIDUAL limbs - Abstract
Objective: This study describes the development and offline validation of a heuristic algorithm for accurate prediction of ground terrain in a lower limb prosthesis. This method is based on inference of the ground terrain geometry using estimation of prosthetic limb kinematics during gait with a single integrated inertial measurement unit. Methods: We asked five subjects with below-knee amputations to traverse level ground, stairs, and ramps using a high-range-of-motion powered prosthesis while internal sensor data were remotely logged. We used these data to develop three terrain prediction algorithms. The first two employed state-of-the-art machine learning approaches, while the third was a directly tuned heuristic using thresholds on estimated prosthetic ankle joint translations and ground slope. We compared the performance of these algorithms using resubstitution error for the machine learning algorithms and overall error for the heuristic algorithm. Results: Our optimal machine learning algorithm attained a resubstitution error of $3.4\%$ using 45 features, while our heuristic method attained an overall prediction error of $2.8\%$ using only 5 features derived from estimation of ground slope and horizontal and vertical ankle joint displacement. Compared with pattern recognition, the heuristic performed better on each individual subject, and across both level and non-level strides. Conclusion and significance: These results demonstrate a method for heuristic prediction of ground terrain in a powered prosthesis. The method is more accurate, more interpretable, and less computationally expensive than machine learning methods considered state-of-the-art for intent recognition, and relies only on integrated prosthesis sensors. Finally, the method provides intuitively tunable thresholds to improve performance for specific walking conditions. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
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204. Optogenetic Peripheral Nerve Immunogenicity.
- Author
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Maimon, Benjamin E., Diaz, Maurizio, Revol, Emilie C. M., Schneider, Alexis M., Leaker, Ben, Varela, Claudia E., Srinivasan, Shriya, Weber, Matthew B., and Herr, Hugh M.
- Abstract
Optogenetic technologies have been the subject of great excitement within the scientific community for their ability to demystify complex neurophysiological pathways in the central (CNS) and peripheral nervous systems (PNS). The excitement surrounding optogenetics has also extended to the clinic with a trial for ChR2 in the treatment of retinitis pigmentosa currently underway and additional trials anticipated for the near future. In this work, we identify the cause of loss-of-expression in response to transdermal illumination of an optogenetically active peroneal nerve following an anterior compartment (AC) injection of AAV6-hSyn-ChR2(H134R) with and without a fluorescent reporter. Using Sprague Dawley Rag2
−/− rats and appropriate controls, we discover optogenetic loss-of-expression is chiefly elicited by ChR2-mediated immunogenicity in the spinal cord, resulting in both CNS motor neuron death and ipsilateral muscle atrophy in both low and high Adeno-Associated Virus (AAV) dosages. We further employ pharmacological immunosuppression using a slow-release tacrolimus pellet to demonstrate sustained transdermal optogenetic expression up to 12 weeks. These results suggest that all dosages of AAV-mediated optogenetic expression within the PNS may be unsafe. Clinical optogenetics for both PNS and CNS applications should take extreme caution when employing opsins to treat disease and may require concurrent immunosuppression. Future work in optogenetics should focus on designing opsins with lesser immunogenicity. [ABSTRACT FROM AUTHOR]- Published
- 2018
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205. POWERED ANKLE-FOOT PROSTHESIS IMPROVES METABOLIC DEMAND OF UNILATERAL TRANSTIBIAL AMPUTEES DURING WALKING.
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Herr, Hugh M. and Grabowski, Alena M.
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PROSTHETICS ,ANKLE ,FOOT ,WALKING ,AMPUTEES ,ACCLIMATIZATION - Abstract
The article presents a study on the impact of the use of the Powerfoot powered ankle-foot prosthesis on the metabolic cost during walking. The researchers observed three healthy adult male unilateral transtibial amputees without neurological, pulmonary or cardiovascular disorder. They also used a certified prosthetist to align and adjust the Powerfoot for every subject during the acclimation session. They found that providing biomimetic power at the prosthetic ankle joint improved preferred walking speed and reduced the metabolic cost of transport.
- Published
- 2010
206. METABOLIC ENERGY AND MUSCLE ACTIVITY REQUIRED FOR NORMAL, EXOSKELETAL, AND ADDED WEIGHT HOPPING.
- Author
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Grabowski, Alena M., Briner, Hazel, Shields, Beth, and Herr, Hugh
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METABOLISM ,MUSCLES ,BODY weight ,HOPPING (Locomotion) ,HUMAN locomotion - Abstract
The article discusses a study of metabolic energy and muscle activity needed during normal two-legged, exoskeletal and added weight hopping. The study involved nine recreational runners who hopped to the beat of the metronome at 2.2, 2.4, 2.6, 2.8, 3.0 and 3.2 hertz (Hz). Ground reaction forces and electromyography (EMG) were measured from the lateral gastrocnemius (LG) and soleus (Sol), among others, during the fourth session. Results show less metabolic power demand during exoskeletal hopping.
- Published
- 2010
207. ELASTIC LEG EXOSKELETON REDUCES THE METABOLIC COST OF HOPPING.
- Author
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Grabowski, Alena M. and Herr, Hugh
- Published
- 2009
208. THE EFFECTS OF SPRINT SPEED ON APPARENT STIFFNESS IN UNI-LATERAL TRANS-TIBIAL AMPUTEE SPRINT RUNNERS.
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McGowan, Craig, Grabowski, Alena, McDermott, William, Kram, Rodger, and Herr, Hugh
- Published
- 2009
209. Presentation highlights: Prosthetic and orthotic limbs.
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Herr, Hugh
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PROSTHETICS , *BIOMEDICAL materials - Abstract
Presents the highlights of a presentation on prosthetic and orthotic limbs during the Prosthetics Roundtable in Rockville, Maryland on June 25, 2001. Development of a lower limb prosthetics that simulate the intricate biomechanics of human walking; Details of the development of an artificial knee at Massachusetts Institute of Technology; Key points of the presentation.
- Published
- 2002
210. Powered Ankle--Foot Prosthesis Improves Walking Metabolic Economy.
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Au, Samuel K., Weber, Jeff, and Herr, Hugh
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PROSTHETICS , *ARTIFICIAL implants , *TECHNOLOGICAL innovations , *AUTOMATIC control systems , *METABOLIC regulation , *ORTHOPEDIC apparatus , *ORTHOPEDIC implants - Abstract
At moderate to fast walking speeds, the human ankle provides net positive work at high-mechanical-power output to propel the body upward and forward during the stance period. On the contrary, conventional ankle-foot prostheses exhibit a passive-elastic response during stance, and consequently, cannot provide net work. Clinical studies indicate that transtibial amputees using conventional prostheses have higher gait metabolic rates than normal. Researchers believe that the main cause for these higher rates is due to the inability of conventional prostheses to provide sufficient positive power at terminal stance in the trailing leg to limit heel strike losses of the adjacent leading leg. In this investigation, we evaluate the hypothesis that a powered ankle-foot prosthesis, capable of providing human-like ankle work and power during stance, can decrease the metabolic cost of transport (COT) compared to a conventional passive-elastic prosthesis. To test the hypothesis, a powered prosthesis is built that comprises a unidirectional spring, configured in parallel with a force-controllable actuator with series elasticity. The prosthesis is shown to deliver the high mechanical power and net positive work observed in normal human walking. The rate of oxygen consumption and carbon dioxide production is measured as a determinant of metabolic rate on three unilateral transtibial amputees walking at self-selected speeds. We find that the powered prosthesis decreases the amputee's metabolic COT on average by 14% compared to the conventional passive-elastic prostheses evaluated (Flex-Foot Ceterus® and Freedom Innovations Sierra), even though the powered system is over twofold heavier than the conventional devices. These results highlight the clinical importance of prosthetic interventions that closely mimic the mass distribution, kinetics, and kinematics of the missing limb. [ABSTRACT FROM AUTHOR]
- Published
- 2009
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211. Powered ankle-foot prosthesis to assist level-ground and stair-descent gaits
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Au, Samuel, Berniker, Max, and Herr, Hugh
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ANKLE , *AMPUTEES , *MUSCLES , *PROSTHETICS , *GAIT in humans , *STAIRS , *ARTIFICIAL neural networks - Abstract
The human ankle varies impedance and delivers net positive work during the stance period of walking. In contrast, commercially available ankle-foot prostheses are passive during stance, causing many clinical problems for transtibial amputees, including non-symmetric gait patterns, higher gait metabolism, and poorer shock absorption. In this investigation, we develop and evaluate a myoelectric-driven, finite state controller for a powered ankle-foot prosthesis that modulates both impedance and power output during stance. The system employs both sensory inputs measured local to the external prosthesis, and myoelectric inputs measured from residual limb muscles. Using local prosthetic sensing, we first develop two finite state controllers to produce biomimetic movement patterns for level-ground and stair-descent gaits. We then employ myoelectric signals as control commands to manage the transition between these finite state controllers. To transition from level-ground to stairs, the amputee flexes the gastrocnemius muscle, triggering the prosthetic ankle to plantar flex at terminal swing, and initiating the stair-descent state machine algorithm. To transition back to level-ground walking, the amputee flexes the tibialis anterior muscle, triggering the ankle to remain dorsiflexed at terminal swing, and initiating the level-ground state machine algorithm. As a preliminary evaluation of clinical efficacy, we test the device on a transtibial amputee with both the proposed controller and a conventional passive-elastic control. We find that the amputee can robustly transition between the finite state controllers through direct muscle activation, allowing rapid transitioning from level-ground to stair walking patterns. Additionally, we find that the proposed finite state controllers result in a more biomimetic ankle response, producing net propulsive work during level-ground walking and greater shock absorption during stair descent. The results of this study highlight the potential of prosthetic leg controllers that exploit neural signals to trigger terrain-appropriate, local prosthetic leg behaviors. [Copyright &y& Elsevier]
- Published
- 2008
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212. Ground Reference Points in Legged Locomotion: Definitions, Biological Trajectories and Control Implications.
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Popovic, Marko B., Goswami, Ambarish, and Herr, Hugh
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LOCOMOTION , *ROBOTICS , *BIOMECHANICS , *HUMAN body , *MOMENTUM (Mechanics) , *TRAJECTORIES (Mechanics) , *BIOPHYSICS - Abstract
The zero moment point (ZMP), foot rotation indicator (FRI) and centroidal moment pivot (CMP) are important ground reference points used for motion identification and control in biomechanics and legged robotics. In this paper, we study these reference points for normal human walking, and discuss their applicability in legged machine control. Since the FRI was proposed as an indicator of foot rotation, we hypothesize that the FRI will closely track the ZMP in early single support when the foot remains fiat on the ground, but will then significantly diverge from the ZMP in late single support as the foot rolls during heel-off Additionally, since spin angular momentum has been shown to remain small throughout the walking cycle, we hypothesize that the CMP will never leave the ground support base throughout the entire gait cycle, closely tracking the ZMP We test these hypotheses using a morphologically realistic human model and kinetic and kinematic gait data measured from ten human subjects walking at self-selected speeds. We find that the mean separation distance between the FRI and ZMP during heel-off is within the accuracy of their measurement (0.1% of foot length). Thus, the FRI point is determined not to be an adequate measure of foot rotational acceleration and a modified FRI point is proposed. Finally, we find that the CMP never leaves the ground support base, and the mean separation distance between the CMP and ZMP is small (14% of foot length), highlighting how closely the human body regulates spin angular momentum in level ground walking. [ABSTRACT FROM AUTHOR]
- Published
- 2005
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213. Augmented.
- Author
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WGBH Boston, Public Broadcasting Service publisher, DaSilva, Jason, director, Herr, Hugh, speaker, Middleton, Naomi, producer, and DaSilva, Jason, producer
- Published
- 2022
214. Restoration of bilateral motor coordination from preserved agonist-antagonist coupling in amputation musculature.
- Author
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Shu, Tony, Huang, Shan Shan, Shallal, Christopher, and Herr, Hugh M.
- Subjects
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MOTOR ability , *AMPUTATION , *MYOELECTRIC prosthesis , *SUBTALAR joint , *ARTIFICIAL joints , *RESIDUAL limbs , *BRAIN-computer interfaces , *MATHEMATICAL optimization - Abstract
Background: Neuroprosthetic devices controlled by persons with standard limb amputation often lack the dexterity of the physiological limb due to limitations of both the user's ability to output accurate control signals and the control system's ability to formulate dynamic trajectories from those signals. To restore full limb functionality to persons with amputation, it is necessary to first deduce and quantify the motor performance of the missing limbs, then meet these performance requirements through direct, volitional control of neuroprosthetic devices. Methods: We develop a neuromuscular modeling and optimization paradigm for the agonist-antagonist myoneural interface, a novel tissue architecture and neural interface for the control of myoelectric prostheses, that enables it to generate virtual joint trajectories coordinated with an intact biological joint at full physiologically-relevant movement bandwidth. In this investigation, a baseline of performance is first established in a population of non-amputee control subjects ( n = 8 ). Then, a neuromuscular modeling and optimization technique is advanced that allows unilateral AMI amputation subjects ( n = 5 ) and standard amputation subjects ( n = 4 ) to generate virtual subtalar prosthetic joint kinematics using measured surface electromyography (sEMG) signals generated by musculature within the affected leg residuum. Results: Using their optimized neuromuscular subtalar models under blindfolded conditions with only proprioceptive feedback, AMI amputation subjects demonstrate bilateral subtalar coordination accuracy not significantly different from that of the non-amputee control group (Kolmogorov-Smirnov test, P ≥ 0.052 ) while standard amputation subjects demonstrate significantly poorer performance (Kolmogorov-Smirnov test, P < 0.001 ). Conclusions: These results suggest that the absence of an intact biological joint does not necessarily remove the ability to produce neurophysical signals with sufficient information to reconstruct physiological movements. Further, the seamless manner in which virtual and intact biological joints are shown to coordinate reinforces the theory that desired movement trajectories are mentally formulated in an abstract task space which does not depend on physical limb configurations. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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215. Neural interfacing architecture enables enhanced motor control and residual limb functionality postamputation.
- Author
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Srinivasan, Shriya S., Gutierrez-Arango, Samantha, Chia-En Teng, Ashley, Israel, Erica, Hyungeun Song, Bailey, Zachary Keith, Carty, Matthew J., Freed, Lisa E., and Herr, Hugh M.
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RESIDUAL limbs , *BRAIN-computer interfaces , *LEG amputation , *MYOELECTRIC prosthesis , *PHANTOM limbs , *AMPUTEES , *TUBERCULOSIS patients - Abstract
Despite advancements in prosthetic technologies, patients with amputation today suffer great diminution in mobility and quality of life. We have developed a modified below-knee amputation (BKA) procedure that incorporates agonist-antagonist myoneural interfaces (AMIs), which surgically preserve and couple agonist-antagonist muscle pairs for the subtalar and ankle joints. AMIs are designed to restore physiological neuromuscular dynamics, enable bidirectional neural signaling, and offer greater neuroprosthetic controllability compared to traditional amputation techniques. In this prospective, nonrandomized, unmasked study design, 15 subjects with AMI below-knee amputation (AB) were matched with 7 subjects who underwent a traditional below-knee amputation (TB). AB subjects demonstrated significantly greater control of their residual limb musculature, production of more differentiable efferent control signals, and greater precision of movement compared to TB subjects (P < 0.008). This may be due to the presence of greater proprioceptive inputs facilitated by the significantly higher fascicle strains resulting from coordinated muscle excursion in AB subjects (P < 0.05). AB subjects reported significantly greater phantom range of motion postamputation (AB: 12.47 ± 2.41, TB: 10.14 ± 1.45 degrees) when compared to TB subjects (P < 0.05). Furthermore, AB subjects also reported less pain (12.25 ± 5.37) than TB subjects (17.29 ± 10.22) and a significant reduction when compared to their preoperative baseline (P < 0.05). Compared with traditional amputation, the construction of AMIs during amputation confers the benefits of enhanced physiological neuromuscular dynamics, proprioception, and phantom limb perception. Subjects' activation of the AMIs produces more differentiable electromyography (EMG) for myoelectric prosthesis control and demonstrates more positive clinical outcomes. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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216. A Framework for Measuring the Time-Varying Shape and Full-Field Deformation of Residual Limbs Using 3-D Digital Image Correlation.
- Author
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Solav, Dana, Moerman, Kevin M., Jaeger, Aaron M., and Herr, Hugh M.
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DIGITAL image correlation , *RESIDUAL limbs , *ARTIFICIAL limbs , *THREE-dimensional imaging , *LEG amputation , *WEARABLE technology - Abstract
Effective prosthetic socket design following lower limb amputation depends upon the accurate characterization of the shape of the residual limb as well as its volume and shape fluctuations. Objective: This study proposes a novel framework for the measurement and analysis of residual limb shape and deformation, using a high-resolution and low-cost system. Methods: A multi-camera system was designed to capture sets of simultaneous images of the entire residuum surface. The images were analyzed using a specially developed open-source three-dimensional digital image correlation (3D-DIC) toolbox, to obtain the accurate time-varying shapes as well as the full-field deformation and strain maps on the residuum skin surface. Measurements on a transtibial amputee residuum were obtained during knee flexions, muscle contractions, and swelling upon socket removal. Results: It was demonstrated that 3D-DIC can be employed to quantify with high resolution time-varying residuum shapes, deformations, and strains. Additionally, the enclosed volumes and cross-sectional areas were computed and analyzed. Conclusion: This novel low-cost framework provides a promising solution for the in vivo evaluation of residuum shapes and strains, as well as has the potential for characterizing the mechanical properties of the underlying soft tissues. Significance: These data may be used to inform data-driven computational algorithms for the design of prosthetic sockets, as well as of other wearable technologies mechanically interfacing with the skin. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
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217. Chapter 19 - A new frontier for orthotics and prosthetics: application of dielectric elastomer actuators to bionics
- Author
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Mulgaonkar, Amit P., Kornbluh, Roy, and Herr, Hugh
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218. Correction to: Restoration of bilateral motor coordination from preserved agonist-antagonist coupling in amputation musculature.
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Shu, Tony, Huang, Shan Shan, Shallal, Christopher, and Herr, Hugh M.
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MOTOR ability , *AMPUTATION , *COUPLES - Abstract
An amendment to this paper has been published and can be accessed via the original article. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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219. Development and Evaluation of a Powered Artificial Gastrocnemius for Transtibial Amputee Gait
- Author
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Michael Frederick Eilenberg, Jiun-Yih Kuan, Hugh M. Herr, Massachusetts Institute of Technology. Department of Mechanical Engineering, Massachusetts Institute of Technology. Media Laboratory, Eilenberg, Michael Frederick, Kuan, Jiun-Yih, and Herr, Hugh M
- Subjects
musculoskeletal diseases ,030506 rehabilitation ,medicine.medical_specialty ,General Computer Science ,Article Subject ,Computer science ,lcsh:Mechanical engineering and machinery ,medicine.medical_treatment ,Amputee gait ,Knee flexion ,Work (physics) ,Prosthesis ,03 medical and health sciences ,Gastrocnemius muscle ,0302 clinical medicine ,Physical medicine and rehabilitation ,medicine.anatomical_structure ,Control and Systems Engineering ,Knee orthosis ,medicine ,lcsh:TJ1-1570 ,Treadmill ,Ankle ,0305 other medical science ,030217 neurology & neurosurgery - Abstract
Existing robotic transtibial prostheses provide only ankle joint actuation and do not restore biarticular function of the gastrocnemius muscle. This paper presents the first powered biarticular transtibial prosthesis, which is a combination of a commercial powered ankle-foot prosthesis and a motorized robotic knee orthosis. The orthosis is controlled to emulate the human gastrocnemius based on neuromuscular models of matched nonamputees. Together with the ankle-foot prosthesis, the devices provide biarticular actuation. We evaluate differences between this biarticular condition and a monoarticular condition with the orthosis behaving as a free-joint. Six participants with transtibial amputation walk with the prosthesis on a treadmill while motion, force, and metabolic data are collected and analyzed for differences between conditions. The biarticular prosthesis reduces affected-side biological knee flexion moment impulse and hip positive work during late-stance knee flexion, compared to the monoarticular condition. The data do not support our hypothesis that metabolism decreases for all participants, but some participants demonstrate large metabolic reductions with the biarticular condition. These preliminary results suggest that a powered artificial gastrocnemius may be capable of providing large metabolic reductions compared to a monoarticular prosthesis, but further study is warranted to determine an appropriate controller for achieving more consistent metabolic benefits., United States. National Aeronautics and Space Administration (Grant NNX12AM16G)
- Published
- 2018
- Full Text
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220. Biomechanic and Energetic Effects of a Quasi-Passive Artificial Gastrocnemius on Transtibial Amputee Gait
- Author
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Michael Frederick Eilenberg, Hugh M. Herr, Ken Endo, Massachusetts Institute of Technology. Computer Science and Artificial Intelligence Laboratory, Massachusetts Institute of Technology. Media Laboratory, Program in Media Arts and Sciences (Massachusetts Institute of Technology), Massachusetts Institute of Technology. Biomechatronics Group, Eilenberg, Michael Frederick, Endo, Ken, and Herr, Hugh M
- Subjects
musculoskeletal diseases ,030506 rehabilitation ,medicine.medical_specialty ,Article Subject ,General Computer Science ,Computer science ,lcsh:Mechanical engineering and machinery ,medicine.medical_treatment ,Knee flexion ,Amputee gait ,Isometric exercise ,Metabolic cost ,Prosthesis ,03 medical and health sciences ,Gastrocnemius muscle ,0302 clinical medicine ,medicine.anatomical_structure ,Physical medicine and rehabilitation ,Control and Systems Engineering ,Knee orthosis ,medicine ,lcsh:TJ1-1570 ,Ankle ,0305 other medical science ,030217 neurology & neurosurgery - Abstract
State-of-the-art transtibial prostheses provide only ankle joint actuation and thus do not provide the biarticular function of the amputated gastrocnemius muscle. We develop a prosthesis that actuates both knee and ankle joints and then evaluate the incremental effects of this prosthesis as compared to ankle actuation alone. The prosthesis employs a quasi-passive clutched-spring knee orthosis, approximating the largely isometric behavior of the biological gastrocnemius, and utilizes a commercial powered ankle-foot prosthesis for ankle joint functionality. Two participants with unilateral transtibial amputation walk with this prosthesis on an instrumented treadmill, while motion, force, and metabolic data are collected. Data are analyzed to determine differences between the biarticular condition with the activation of the knee orthosis and the monoarticular condition with the orthosis behaving as a free-joint. As hypothesized, the biarticular system is shown to reduce both affected-side knee and hip moment impulse and positive mechanical work in both participants during the late stance knee flexion phase of walking, compared to the monoarticular condition. The metabolic cost of walking is also reduced for both participants. These very preliminary results suggest that biarticular functionality may provide benefits beyond even those of the most advanced monoarticular prostheses., Massachusetts Institute of Technology. Media Laboratory
- Published
- 2017
221. Human Leg Model Predicts Muscle Forces, States, and Energetics during Walking
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Hugh M. Herr, Jared Markowitz, Massachusetts Institute of Technology. Media Laboratory, Markowitz, Jared John, and Herr, Hugh M.
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0301 basic medicine ,Male ,Muscle Physiology ,Computer science ,Physiology ,Kinematics ,Electromyography ,Walking ,Tendons ,Medicine and Health Sciences ,Biomechanics ,Human leg ,Musculoskeletal System ,Gait ,lcsh:QH301-705.5 ,Ecology ,medicine.diagnostic_test ,Physics ,Classical Mechanics ,Gait cycle ,Metabolic efficiency ,Tendon ,Biomechanical Phenomena ,medicine.anatomical_structure ,Bioassays and Physiological Analysis ,Computational Theory and Mathematics ,Connective Tissue ,Modeling and Simulation ,Physical Sciences ,Anatomy ,Muscle Electrophysiology ,Algorithms ,Research Article ,Muscle Contraction ,Optimization ,Adult ,Research and Analysis Methods ,Models, Biological ,Pelvis ,03 medical and health sciences ,Cellular and Molecular Neuroscience ,Motion ,Young Adult ,Control theory ,Genetics ,medicine ,Torque ,Humans ,Computer Simulation ,Muscle, Skeletal ,Molecular Biology ,Ecology, Evolution, Behavior and Systematics ,Simulation ,Leg ,Hip ,Biological Locomotion ,Electrophysiological Techniques ,Biology and Life Sciences ,Computational Biology ,Bayes Theorem ,Metabolic cost ,Joints (Anatomy) ,030104 developmental biology ,Biological Tissue ,lcsh:Biology (General) ,Musculoskeletal Mechanics ,Energy Metabolism ,Mathematics - Abstract
Humans employ a high degree of redundancy in joint actuation, with different combinations of muscle and tendon action providing the same net joint torque. Both the resolution of these redundancies and the energetics of such systems depend on the dynamic properties of muscles and tendons, particularly their force-length relations. Current walking models that use stock parameters when simulating muscle-tendon dynamics tend to significantly overestimate metabolic consumption, perhaps because they do not adequately consider the role of elasticity. As an alternative, we posit that the muscle-tendon morphology of the human leg has evolved to maximize the metabolic efficiency of walking at self-selected speed. We use a data-driven approach to evaluate this hypothesis, utilizing kinematic, kinetic, electromyographic (EMG), and metabolic data taken from five participants walking at self-selected speed. The kinematic and kinetic data are used to estimate muscle-tendon lengths, muscle moment arms, and joint moments while the EMG data are used to estimate muscle activations. For each subject we perform an optimization using prescribed skeletal kinematics, varying the parameters that govern the force-length curve of each tendon as well as the strength and optimal fiber length of each muscle while seeking to simultaneously minimize metabolic cost and maximize agreement with the estimated joint moments. We find that the metabolic cost of transport (MCOT) values of our participants may be correctly matched (on average 0.36±0.02 predicted, 0.35±0.02 measured) with acceptable joint torque fidelity through application of a single constraint to the muscle metabolic budget. The associated optimal muscle-tendon parameter sets allow us to estimate the forces and states of individual muscles, resolving redundancies in joint actuation and lending insight into the potential roles and control objectives of the muscles of the leg throughout the gait cycle., Author Summary Neuromuscular systems often employ redundancy in joint actuation, with different combinations of muscle and tendon action producing the same net joint torque. Both the resolution of these redundancies and the energetics of such systems depend strongly on the force-length relations of muscles and tendons. Many human walking models fail to properly account for elasticity by failing to scale muscle-tendon parameters for different individuals, relying instead on stock values taken from cadaver studies. This can result in inaccurate estimates of metabolic consumption as well as of the forces and states of individual muscles. Instead we estimate muscle-tendon parameters using a data-driven optimization procedure, testing the hypothesis that the human leg has evolved to maximize the metabolic efficiency of walking at self-selected speed. We find that the experimentally observed metabolic consumption can be matched with reasonable joint torque fidelity through the addition of a single constraint on the per-muscle metabolic budget. The associated muscle-tendon parameter sets were used to compute muscle force and state estimates, lending insight into potential roles and control objectives of the major muscles of the leg throughout the gait cycle.
- Published
- 2015
222. Design and Testing of a Bionic Dancing Prosthesis
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Robert W. Emerson, Nathan C. Villagaray-Carski, Elliott J. Rouse, Hugh M. Herr, Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology. Media Laboratory, Program in Media Arts and Sciences (Massachusetts Institute of Technology), Rouse, Elliott J., Villagaray-Carski, Nathan C., and Herr, Hugh M.
- Subjects
Adult ,Bionics ,medicine.medical_specialty ,Activities of daily living ,Dance ,medicine.medical_treatment ,lcsh:Medicine ,Motor Activity ,Prosthesis Design ,Prosthesis ,Amputation, Surgical ,medicine ,Daily living ,Humans ,Dancing ,lcsh:Science ,Multidisciplinary ,Work (physics) ,lcsh:R ,Biomechanics ,medicine.anatomical_structure ,Amputation ,Physical therapy ,lcsh:Q ,Female ,Ankle ,Psychology ,Research Article - Abstract
Traditionally, prosthetic leg research has focused on improving mobility for activities of daily living. Artistic expression such as dance, however, is not a common research topic and consequently prosthetic technology for dance has been severely limited for the disabled. This work focuses on investigating the ankle joint kinetics and kinematics during a Latin-American dance to provide unique motor options for disabled individuals beyond those of daily living. The objective of this study was to develop a control system for a bionic ankle prosthesis that outperforms conventional prostheses when dancing the rumba. The biomechanics of the ankle joint of a non-amputee, professional dancer were acquired for the development of the bionic control system. Subsequently, a professional dancer who received a traumatic transtibial amputation in April 2013 tested the bionic dance prosthesis and a conventional, passive prosthesis for comparison. The ability to provide similar torque-angle behavior of the biological ankle was assessed to quantify the biological realism of the prostheses. The bionic dancing prosthesis overlapped with 37 ± 6% of the non-amputee ankle torque and ankle angle data, compared to 26 ± 2% for the conventional, passive prosthesis, a statistically greater overlap (p = 0.01). This study lays the foundation for quantifying unique, expressive activity modes currently unavailable to individuals with disabilities. Future work will focus on an expansion of the methods and types of dance investigated in this work., Massachusetts Institute of Technology. Media Laboratory
- Published
- 2015
223. Autonomous exoskeleton reduces metabolic cost of human walking
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Elliott J. Rouse, Luke M. Mooney, Hugh M. Herr, Massachusetts Institute of Technology. Department of Mechanical Engineering, Massachusetts Institute of Technology. Media Laboratory, Program in Media Arts and Sciences (Massachusetts Institute of Technology), Mooney, Luke M., Rouse, Elliott J., and Herr, Hugh M.
- Subjects
0209 industrial biotechnology ,Engineering ,medicine.medical_specialty ,Orthotic Devices ,Short Report ,Health Informatics ,02 engineering and technology ,Walking ,Prosthesis Design ,03 medical and health sciences ,Autonomous ,020901 industrial engineering & automation ,0302 clinical medicine ,Physical medicine and rehabilitation ,medicine ,Humans ,Treadmill ,Human locomotion ,Mechanical energy ,business.industry ,Rehabilitation ,Robotics ,Gait cycle ,Metabolic cost ,Orthotic device ,Exoskeleton ,Power ,Artificial intelligence ,Metabolic ,business ,Energy Metabolism ,030217 neurology & neurosurgery ,Ankle Joint - Abstract
Background: Passive exoskeletons that assist with human locomotion are often lightweight and compact, but are unable to provide net mechanical power to the exoskeletal wearer. In contrast, powered exoskeletons often provide biologically appropriate levels of mechanical power, but the size and mass of their actuator/power source designs often lead to heavy and unwieldy devices. In this study, we extend the design and evaluation of a lightweight and powerful autonomous exoskeleton evaluated for loaded walking in (J Neuroeng Rehab 11:80, 2014) to the case of unloaded walking conditions. Findings: The metabolic energy consumption of seven study participants (85 ± 12 kg body mass) was measured while walking on a level treadmill at 1.4 m/s. Testing conditions included not wearing the exoskeleton and wearing the exoskeleton, in both powered and unpowered modes. When averaged across the gait cycle, the autonomous exoskeleton applied a mean positive mechanical power of 26 ± 1 W (13 W per ankle) with 2.12 kg of added exoskeletal foot-shank mass (1.06 kg per leg). Use of the leg exoskeleton significantly reduced the metabolic cost of walking by 35 ± 13 W, which was an improvement of 10 ± 3% (p = 0.023) relative to the control condition of not wearing the exoskeleton. Conclusions: The results of this study highlight the advantages of developing lightweight and powerful exoskeletons that can comfortably assist the body during walking., National Science Foundation (U.S.). Graduate Research Fellowship (Award 1122374)
- Published
- 2014
224. Autonomous exoskeleton reduces metabolic cost of human walking during load carriage
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Elliott J. Rouse, Hugh M. Herr, Luke M. Mooney, Harvard University--MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology. Department of Mechanical Engineering, Program in Media Arts and Sciences (Massachusetts Institute of Technology), Mooney, Luke M., Rouse, Elliott Jay, and Herr, Hugh M.
- Subjects
Male ,medicine.medical_specialty ,Engineering ,Orthotic Devices ,Powered exoskeleton ,Health Informatics ,Walking ,medicine.disease_cause ,Prosthesis Design ,Weight-bearing ,Weight-Bearing ,Young Adult ,Physical medicine and rehabilitation ,11. Sustainability ,medicine ,Humans ,Treadmill ,Muscle, Skeletal ,Mechanical energy ,business.industry ,Research ,Rehabilitation ,Robotics ,Orthotic device ,Exoskeleton ,Biomechanical Phenomena ,medicine.anatomical_structure ,Physical therapy ,Artificial intelligence ,Ankle ,business ,Energy Metabolism ,human activities - Abstract
Background: Many soldiers are expected to carry heavy loads over extended distances, often resulting in physical and mental fatigue. In this study, the design and testing of an autonomous leg exoskeleton is presented. The aim of the device is to reduce the energetic cost of loaded walking. In addition, we present the Augmentation Factor, a general framework of exoskeletal performance that unifies our results with the varying abilities of previously developed exoskeletons. Methods: We developed an autonomous battery powered exoskeleton that is capable of providing substantial levels of positive mechanical power to the ankle during the push-off region of stance phase. We measured the metabolic energy consumption of seven subjects walking on a level treadmill at 1.5 m/s, while wearing a 23 kg vest. Results: During the push-off portion of the stance phase, the exoskeleton applied positive mechanical power with an average across the gait cycle equal to 23 ± 2 W (11.5 W per ankle). Use of the autonomous leg exoskeleton significantly reduced the metabolic cost of walking by 36 ± 12 W, which was an improvement of 8 ± 3% (p = 0.025) relative to the control condition of not wearing the exoskeleton. Conclusions: In the design of leg exoskeletons, the results of this study highlight the importance of minimizing exoskeletal power dissipation and added limb mass, while providing substantial positive power during the walking gait cycle., National Science Foundation (U.S.) (Graduate Research Fellowship award number 1122374), United States. National Aeronautics and Space Administration (NASA award number NNX12AR09G), United States. Dept. of Defense (Award number 119–000245)
- Published
- 2014
225. Proportional EMG control of ankle plantar flexion in a powered transtibial prosthesis
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Jing Wang, Hugh M. Herr, Oliver Alan Kannape, Massachusetts Institute of Technology. Media Laboratory, Program in Media Arts and Sciences (Massachusetts Institute of Technology), Kannape, Oliver Alan, Wang, Jing, and Herr, Hugh M.
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musculoskeletal diseases ,Male ,medicine.medical_specialty ,medicine.medical_treatment ,0206 medical engineering ,B121 ,Artificial Limbs ,02 engineering and technology ,Electromyography ,Prosthesis Design ,Prosthesis ,Plantar flexion ,03 medical and health sciences ,0302 clinical medicine ,Amputees ,medicine ,Humans ,Range of Motion, Articular ,Muscle, Skeletal ,medicine.diagnostic_test ,business.industry ,Work (physics) ,Robotics ,musculoskeletal system ,020601 biomedical engineering ,Gait ,Biomechanical Phenomena ,B900 ,Preferred walking speed ,body regions ,medicine.anatomical_structure ,Gait analysis ,Physical therapy ,Ankle ,business ,human activities ,030217 neurology & neurosurgery - Abstract
The human calf muscle generates 80% of the mechanical work to walk throughout stance-phase, powered plantar flexion. Powered plantar flexion is not only important for walking energetics, but also to minimize the impact on the leading leg at heel-strike. For unilateral transtibial amputees, it has recently been shown that knee load on the leading, intact limb decreases as powered plantar flexion in the trailing prosthetic ankle increases. Not surprisingly, excessive loads on the leading, intact knee are believed to be causative of knee osteoarthritis, a leading secondary impairment in lowerextremity amputees. In this study, we hypothesize that a transtibial amputee can learn how to control a powered anklefoot prosthesis using a volitional electromyographic (EMG) control to directly modulate ankle powered plantar flexion. We here present preliminary data, and find that an amputee participant is able to modulate toe-off angle, net ankle work and peak power across a broad range of walking speeds by volitionally modulating calf EMG activity. The modulation of these key gait parameters is shown to be comparable to the dynamical response of the same powered prosthesis controlled intrinsically (No EMG), suggesting that transtibial amputees can achieve an adequate level of powered plantar flexion controllability using direct volitional EMG control., United States. Dept. of Defense (award number 6920559), United States. Dept. of Defense (award number 6920877), Swiss National Science Foundation (grant PBELP3_140656)
- Published
- 2013
226. Clutchable series-elastic actuator: design of a robotic knee prosthesis for minimum energy consumption
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Ernesto C. Martinez-Villalpando, Hugh M. Herr, Luke M. Mooney, Elliott J. Rouse, Massachusetts Institute of Technology. Department of Mechanical Engineering, Massachusetts Institute of Technology. Media Laboratory, Rouse, Elliott Jay, Mooney, Luke M., Martinez-Villalpando, Ernesto C., and Herr, Hugh M.
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Engineering ,business.industry ,Work (physics) ,Energy consumption ,Robotics ,Walking ,Models, Theoretical ,Prosthesis Design ,Energy storage ,Elasticity ,Biomechanical Phenomena ,Mechanism (engineering) ,Energy Transfer ,Torque ,Control theory ,Spring (device) ,Humans ,Clutch ,Actuator ,business ,Knee Prosthesis - Abstract
The cyclic and often linear torque-angle relationship of locomotion presents the opportunity to innovate on the design of traditional series-elastic actuators (SEAs). In this paper, a novel modification to the SEA architecture was proposed by adding a clutch in parallel with the motor within the SEA—denoted as a CSEA. This addition permits bimodal dynamics where the system is characterized by an SEA when the clutch is disengaged and a passive spring when the clutch is engaged. The purpose of the parallel clutch was to provide the ability to store energy in a tuned series spring, while requiring only reactionary torque from the clutch. Thus, when the clutch is engaged, a tuned elastic relationship can be achieved with minimal electrical energy consumption. The state-based model of the CSEA is introduced and the implementation of the CSEA mechanism in a powered knee prosthesis is detailed. The series elasticity was optimized to fit the spring-like torqueangle relationship of early stance phase knee flexion and extension during level ground walking. In simulation, the CSEA knee required 70% less electrical energy than a traditional SEA. Future work will focus on the mechanical implementation of the CSEA knee and an empirical demonstration of reduced electrical energy consumption during walking., United States. Dept. of Defense (National Defense Science and Engineering Graduate Fellowship Award 1122374)
- Published
- 2013
227. The biomechanics and energetics of human running using an elastic knee exoskeleton
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Grant Elliott, Hugh M. Herr, Gregory S. Sawicki, Andrew Marecki, Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology. Department of Mechanical Engineering, Massachusetts Institute of Technology. Media Laboratory, Program in Media Arts and Sciences (Massachusetts Institute of Technology), Herr, Hugh M., Elliott, Grant, and Marecki, Andrew
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musculoskeletal diseases ,medicine.medical_specialty ,Engineering ,Electromyography ,Orthotics ,Running ,Physical medicine and rehabilitation ,medicine ,Humans ,Torque ,Knee ,Analysis of Variance ,medicine.diagnostic_test ,business.industry ,Biomechanics ,Stiffness ,musculoskeletal system ,Brace ,Biomechanical Phenomena ,Exoskeleton ,Gait analysis ,Physical therapy ,medicine.symptom ,Knee Prosthesis ,business ,human activities - Abstract
While the effects of series compliance on running biomechanics are well documented, the effects of parallel compliance are known only for the simpler case of hopping. As many practical exoskeletal and orthotic designs act in parallel with the leg, it is desirable to understand the effects of such an intervention. Spring-like forces offer a natural choice of perturbation for running, as they are both biologically motivated and energetically inexpensive to implement. To this end, we investigate the hypothesis that the addition of an external elastic element at the knee during the stance phase of running results in a reduction in knee extensor activation so that total joint quasi-stiffness is maintained. An exoskeletal knee brace consisting of an elastic element engaged by a clutch is used to provide this stance phase extensor torque. Motion capture of five subjects is used to investigate the consequences of running with this device. No significant change in leg stiffness or total knee stiffness is observed due to the activation of the clutched parallel knee spring. However, this pilot data suggests differing responses between casual runners and competitive long-distance runners, whose total knee torque is increased by the device. Such a relationship between past training and effective utilization of an external force is suggestive of limitations on the applicability of assistive devices.
- Published
- 2013
228. Continuously-variable series-elastic actuator
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Luke M. Mooney, Hugh M. Herr, Massachusetts Institute of Technology. Department of Mechanical Engineering, Massachusetts Institute of Technology. Media Laboratory, Program in Media Arts and Sciences (Massachusetts Institute of Technology), Mooney, Luke M., and Herr, Hugh M.
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Engineering ,business.industry ,Signal Processing, Computer-Assisted ,Energy consumption ,Prosthesis Design ,Elasticity ,Physics::Geophysics ,Exoskeleton ,Computer Science::Robotics ,Energy conservation ,Control theory ,Robot ,Torque ,business ,Actuator ,Monte Carlo Method ,Physics::Atmospheric and Oceanic Physics ,Mechanical energy ,Efficient energy use - Abstract
Actuator efficiency is an important factor in the design of powered leg prostheses, orthoses, exoskeletons, and legged robots. A continuously-variable series-elastic actuator (CV-SEA) is presented as an efficient actuator for legged locomotion. The CV-SEA implements a continuously-variable transmission (CVT) between a motor and series elastic element. The CVT reduces the torque seen at the motor and allows the motor to operate in speed regimes of higher efficiency, while the series-elastic element efficiently stores and releases mechanical energy, reducing motor work requirements for actuator applications where an elastic response is sought. An energy efficient control strategy for the CV-SEA was developed using a Monte-Carlo minimization method that randomly generates transmission profiles and converges on those that minimize the electrical energy consumption of the motor. The CV-SEA is compared to a standard SEA and an infinitely variable series elastic actuator (IV-SEA). Simulations suggest that a CV-SEA will require less energy that an SEA or IV-SEA when used in a knee prosthesis during level-ground walking., United States. Dept. of Defense (award number W81XWH-09-2-0143), National Science Foundation (U.S.) (Graduate Research Fellowship award number 1122374)
- Published
- 2013
229. A method to determine the optimal features for control of a powered lower-limb prostheses
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M Todd Farrell, Hugh M. Herr, Massachusetts Institute of Technology. Media Laboratory. Biomechatronics Group, Massachusetts Institute of Technology. Media Laboratory, Program in Media Arts and Sciences (Massachusetts Institute of Technology), Farrell, Matthew T., and Herr, Hugh M.
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Engineering ,medicine.medical_specialty ,Leg ,Modalities ,business.industry ,Electromyography ,Feature extraction ,Amputation Stumps ,Terrain ,Artificial Limbs ,Biofeedback, Psychology ,Robotics ,Actigraphy ,Artificial limbs ,Lower limb ,Amputees ,Therapy, Computer-Assisted ,Physical therapy ,medicine ,Humans ,Computer vision ,Artificial intelligence ,business ,Control (linguistics) ,Feature combination - Abstract
Lower-limb prostheses are rapidly advancing with greater computing power and sensing modalities. This paper is an attempt to begin exploring the trade-off between extrinsic and intrinsic control modalities. In this case, between electromyographic (extrinsic) and several internal sensors that can be used for intrinsic control. We propose a method that will identify the particular features, taken from two trans-femoral amputee and one trans-tibial amputee, during locomotion on varying terrain, that perfectly discriminate between locomotion modes. From this we are able to identify the source of the discriminability from a large-set of features that does not depend on the type of amputation. Also, we comment on the use of this algorithm in selecting the most discriminatory and least encumbering sensor/feature combination for transitions when the ground underneath the foot is unknown for trans-tibial amputees.
- Published
- 2011
230. Human Leg Model Predicts Ankle Muscle-Tendon Morphology, State, Roles and Energetics in Walking
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Hugh M. Herr, Emery N. Brown, Pavitra Krishnaswamy, Harvard University--MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology. Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology. Media Laboratory, Program in Media Arts and Sciences (Massachusetts Institute of Technology), Brown, Emery N., Krishnaswamy, Pavitra, and Herr, Hugh M.
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Male ,Models, Anatomic ,02 engineering and technology ,Kinematics ,Electromyography ,Walking ,0302 clinical medicine ,Gait (human) ,Neuroscience/Motor Systems ,Human leg ,lcsh:QH301-705.5 ,Gait ,Computational Biology/Systems Biology ,Ecology ,medicine.diagnostic_test ,Biomechanics ,3. Good health ,Biomechanical Phenomena ,medicine.anatomical_structure ,Computational Theory and Mathematics ,Modeling and Simulation ,Algorithms ,Research Article ,Biophysics/Theory and Simulation ,Computer Science/Systems and Control Theory ,medicine.medical_specialty ,0206 medical engineering ,Musculoskeletal Physiological Phenomena ,Models, Biological ,03 medical and health sciences ,Cellular and Molecular Neuroscience ,Gastrocnemius muscle ,Physical medicine and rehabilitation ,Genetics ,medicine ,Humans ,Neuroscience/Theoretical Neuroscience ,Molecular Biology ,Ecology, Evolution, Behavior and Systematics ,Simulation ,Leg ,Computational Biology ,Bayes Theorem ,020601 biomedical engineering ,lcsh:Biology (General) ,Ankle ,030217 neurology & neurosurgery ,Mathematics - Abstract
A common feature in biological neuromuscular systems is the redundancy in joint actuation. Understanding how these redundancies are resolved in typical joint movements has been a long-standing problem in biomechanics, neuroscience and prosthetics. Many empirical studies have uncovered neural, mechanical and energetic aspects of how humans resolve these degrees of freedom to actuate leg joints for common tasks like walking. However, a unifying theoretical framework that explains the many independent empirical observations and predicts individual muscle and tendon contributions to joint actuation is yet to be established. Here we develop a computational framework to address how the ankle joint actuation problem is resolved by the neuromuscular system in walking. Our framework is founded upon the proposal that a consideration of both neural control and leg muscle-tendon morphology is critical to obtain predictive, mechanistic insight into individual muscle and tendon contributions to joint actuation. We examine kinetic, kinematic and electromyographic data from healthy walking subjects to find that human leg muscle-tendon morphology and neural activations enable a metabolically optimal realization of biological ankle mechanics in walking. This optimal realization (a) corresponds to independent empirical observations of operation and performance of the soleus and gastrocnemius muscles, (b) gives rise to an efficient load-sharing amongst ankle muscle-tendon units and (c) causes soleus and gastrocnemius muscle fibers to take on distinct mechanical roles of force generation and power production at the end of stance phase in walking. The framework outlined here suggests that the dynamical interplay between leg structure and neural control may be key to the high walking economy of humans, and has implications as a means to obtain insight into empirically inaccessible features of individual muscle and tendons in biomechanical tasks., National Institutes of Health (U.S.) (NIH Pioneer Award DP1 OD003646), Massachusetts Institute of Technology. Media Laboratory (Consortia Account 2736448), Massachusetts Institute of Technology. Media Laboratory (Consortia Account 6895867)
- Published
- 2011
231. Exoskeletons and orthoses: classification, design challenges and future directions
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Hugh M. Herr, Harvard University--MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology. Media Laboratory, Herr, Hugh M., and Program in Media Arts and Sciences (Massachusetts Institute of Technology)
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Bionics ,Leg ,Orthotic Devices ,medicine.medical_specialty ,Engineering ,business.industry ,Rehabilitation ,Health Informatics ,Equipment Design ,Orthotic device ,lcsh:RC321-571 ,Exoskeleton ,Weight-Bearing ,Physical medicine and rehabilitation ,Arm ,Physical Endurance ,Commentary ,medicine ,Humans ,Engineering ethics ,business ,lcsh:Neurosciences. Biological psychiatry. Neuropsychiatry ,Locomotion ,Residual limb - Abstract
For over a century, technologists and scientists have actively sought the development of exoskeletons and orthoses designed to augment human economy, strength, and endurance. While there are still many challenges associated with exoskeletal and orthotic design that have yet to be perfected, the advances in the field have been truly impressive. In this commentary, I first classify exoskeletons and orthoses into devices that act in series and in parallel to a human limb, providing a few examples within each category. This classification is then followed by a discussion of major design challenges and future research directions critical to the field of exoskeletons and orthoses., Massachusetts Institute of Technology. Media Laboratory
- Published
- 2009
232. 3D Ultrasound Shear Wave Elastography for Musculoskeletal Tissue Assessment Under Compressive Load: A Feasibility Study.
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Ranger BJ, Moerman KM, Feigin M, Herr HM, and Anthony BW
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- Humans, Elasticity Imaging Techniques methods, Feasibility Studies, Phantoms, Imaging, Imaging, Three-Dimensional methods
- Abstract
Given its real-time capability to quantify mechanical tissue properties, ultrasound shear wave elastography holds significant promise in clinical musculoskeletal imaging. However, existing shear wave elastography methods fall short in enabling full-limb analysis of 3D anatomical structures under diverse loading conditions, and may introduce measurement bias due to sonographer-applied force on the transducer. These limitations pose numerous challenges, particularly for 3D computational biomechanical tissue modeling in areas like prosthetic socket design. In this feasibility study, a clinical linear ultrasound transducer system with integrated shear wave elastography capabilities was utilized to scan both a calibrated phantom and human limbs in a water tank imaging setup. By conducting 2D and 3D scans under varying compressive loads, this study demonstrates the feasibility of volumetric ultrasound shear wave elastography of human limbs. Our preliminary results showcase a potential method for evaluating 3D spatially varying tissue properties, offering future extensions to computational biomechanical modeling of tissue for various clinical scenarios., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
- Published
- 2024
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233. Variable-stiffness prosthesis improves biomechanics of walking across speeds compared to a passive device.
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Rogers-Bradley E, Yeon SH, Landis C, Lee DRC, and Herr HM
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- Humans, Biomechanical Phenomena, Male, Female, Adult, Middle Aged, Walking Speed physiology, Gait physiology, Amputees rehabilitation, Artificial Limbs, Walking physiology, Prosthesis Design
- Abstract
Ankle push-off power plays an important role in healthy walking, contributing to center-of-mass acceleration, swing leg dynamics, and accounting for 45% of total leg power. The majority of existing passive energy storage and return prostheses for people with below-knee (transtibial) amputation are stiffer than the biological ankle, particularly at slower walking speeds. Additionally, passive devices provide insufficient levels of energy return and push-off power, negatively impacting biomechanics of gait. Here, we present a clinical study evaluating the kinematics and kinetics of walking with a microprocessor-controlled, variable-stiffness ankle-foot prosthesis (945 g) compared to a standard low-mass passive prosthesis (Ottobock Taleo, 463 g) with 7 study participants having unilateral transtibial amputation. By modulating prosthesis stiffness under computer control across walking speeds, we demonstrate that there exists a stiffness that increases prosthetic-side energy return, peak power, and center-of-mass push-off work, and decreases contralateral limb peak ground reaction force compared to the standard passive prosthesis across all evaluated walking speeds. We demonstrate a significant increase in center-of-mass push-off work of 26.1%, 26.2%, 29.6% and 29.9% at 0.75 m/s, 1.0 m/s, 1.25 m/s, and 1.5 m/s, respectively, and a significant decrease in contralateral limb ground reaction force of 3.1%, 3.9%, and 3.2% at 1.0 m/s, 1.25 m/s, and 1.5 m/s, respectively. This study demonstrates the potential for a quasi-passive microprocessor-controlled variable-stiffness prosthesis to increase push-off power and energy return during gait at a range of walking speeds compared to a passive device of a fixed stiffness., (© 2024. The Author(s).)
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- 2024
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234. Continuous neural control of a bionic limb restores biomimetic gait after amputation.
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Song H, Hsieh TH, Yeon SH, Shu T, Nawrot M, Landis CF, Friedman GN, Israel EA, Gutierrez-Arango S, Carty MJ, Freed LE, and Herr HM
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- Humans, Male, Middle Aged, Adult, Female, Muscle, Skeletal innervation, Walking, Leg surgery, Artificial Limbs, Gait physiology, Amputation, Surgical, Amputees, Bionics, Biomimetics methods
- Abstract
For centuries scientists and technologists have sought artificial leg replacements that fully capture the versatility of their intact biological counterparts. However, biological gait requires coordinated volitional and reflexive motor control by complex afferent and efferent neural interplay, making its neuroprosthetic emulation challenging after limb amputation. Here we hypothesize that continuous neural control of a bionic limb can restore biomimetic gait after below-knee amputation when residual muscle afferents are augmented. To test this hypothesis, we present a neuroprosthetic interface consisting of surgically connected, agonist-antagonist muscles including muscle-sensing electrodes. In a cohort of seven leg amputees, the interface is shown to augment residual muscle afferents by 18% of biologically intact values. Compared with a matched amputee cohort without the afferent augmentation, the maximum neuroprosthetic walking speed is increased by 41%, enabling equivalent peak speeds to persons without leg amputation. Further, this level of afferent augmentation enables biomimetic adaptation to various walking speeds and real-world environments, including slopes, stairs and obstructed pathways. Our results suggest that even a small augmentation of residual muscle afferents restores biomimetic gait under continuous neuromodulation in individuals with leg amputation., (© 2024. The Author(s).)
- Published
- 2024
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235. Closed-loop optogenetic neuromodulation enables high-fidelity fatigue-resistant muscle control.
- Author
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Herrera-Arcos G, Song H, Yeon SH, Ghenand O, Gutierrez-Arango S, Sinha S, and Herr H
- Subjects
- Animals, Humans, Electric Stimulation instrumentation, Muscle Contraction physiology, Robotics instrumentation, Male, Equipment Design, Neural Prostheses, Nonlinear Dynamics, Optogenetics methods, Optogenetics instrumentation, Muscle Fatigue physiology, Muscle, Skeletal physiology
- Abstract
Closed-loop neuroprostheses show promise in restoring motion in individuals with neurological conditions. However, conventional activation strategies based on functional electrical stimulation (FES) fail to accurately modulate muscle force and exhibit rapid fatigue because of their unphysiological recruitment mechanism. Here, we present a closed-loop control framework that leverages physiological force modulation under functional optogenetic stimulation (FOS) to enable high-fidelity muscle control for extended periods of time (>60 minutes) in vivo. We first uncovered the force modulation characteristic of FOS, showing more physiological recruitment and significantly higher modulation ranges (>320%) compared with FES. Second, we developed a neuromuscular model that accurately describes the highly nonlinear dynamics of optogenetically stimulated muscle. Third, on the basis of the optogenetic model, we demonstrated real-time control of muscle force with improved performance and fatigue resistance compared with FES. This work lays the foundation for fatigue-resistant neuroprostheses and optogenetically controlled biohybrid robots with high-fidelity force modulation.
- Published
- 2024
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236. Non-pyrogenicity and biocompatibility of parylene-coated magnetic bead implants.
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Taylor CR, Nott JK, Ratnasena NH, Cohen JM, and Herr HM
- Abstract
Clinical grade magnetic bead implants have important applications in interfacing with the human body, providing contactless mechanical attachment or wireless communication through human tissue. We recently developed a new strategy, magnetomicrometry, that uses magnetic bead implants as passive communication devices to wirelessly sense muscle tissue lengths. We manufactured clinical-grade magnetic bead implants and verified their biocompatibility via intramuscular implantation, cytotoxicity, sensitization, and intracutaneous irritation testing. In this work, we test the pyrogenicity of the magnetic bead implants via a lagomorph model, and we test the biocompatibility of the magnetic bead implants via a full chemical characterization and toxicological risk assessment. Further, we test the cleaning, sterilization, and dry time of the devices that are used to deploy these magnetic bead implants. We find that the magnetic bead implants are non-pyrogenic and biocompatible, with the insertion device determined to be safe to clean, sterilize, and dry in a healthcare setting. These results provide confidence for the safe use of these magnetic bead implants in humans., Competing Interests: Authors JN and NR were employed by the company RQM+. Author JC was employed by the company Gradient Corp. Authors CT and HH have filed patents on the magnetomicrometry concept entitled “Method for neuromechanical and neuroelectromagnetic mitigation of limb pathology” (PCT/US18/55053) and on implementation strategies for magnetomicrometry entitled “Magnetomicrometric advances in robotic control” (PCT/US2021/056092)., (Copyright © 2024 Taylor, Nott, Ratnasena, Cohen and Herr.)
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- 2024
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237. Resting state neurophysiology of agonist-antagonist myoneural interface in persons with transtibial amputation.
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Chicos L, Rangaprakash D, Barry R, and Herr H
- Abstract
The agonist-antagonist myoneural interface (AMI) is a novel amputation surgery that preserves sensorimotor signaling mechanisms of the central-peripheral nervous systems. Our first neuroimaging study investigating AMI subjects ( Srinivasan et al., Sci. Transl. Med. 2020 ) focused on task-based neural signatures, and showed evidence of proprioceptive feedback to the central nervous system. The study of resting state neural activity helps non-invasively characterize the neural patterns that prime task response. In this first study on resting state fMRI in AMI subjects, we compared resting state functional connectivity in patients with transtibial AMI (n=12) and traditional (n=7) amputations, as well as biologically intact control subjects (n=10). We hypothesized that the AMI surgery will induce functional network reorganization that significantly differs from the traditional amputation surgery and also more closely resembles the neural configuration of controls. We found AMI subjects to have lower connectivity with salience and motor seed regions compared to traditional amputees. Additionally, with connections affected in traditional amputees, AMI subjects exhibited a connectivity pattern more closely resembling controls. Lastly, sensorimotor connectivity in amputee cohorts was significantly associated with phantom sensation (R
2 =0.7, p =0.0008). These findings provide researchers and clinicians with a critical mechanistic understanding of the effects of the AMI surgery on the brain at rest, spearheading future research towards improved prosthetic control and embodiment., Competing Interests: Conflicts of interest The authors report no competing interests.- Published
- 2023
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238. Constitutive parameter identification of transtibial residual limb soft tissue using ultrasound indentation and shear wave elastography.
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Ranger BJ, Moerman KM, Anthony BW, and Herr HM
- Subjects
- Humans, Finite Element Analysis, Prosthesis Design, Ultrasonography, Disease Progression, Elasticity Imaging Techniques
- Abstract
Finite element analysis (FEA) can be used to evaluate applied interface pressures and internal tissue strains for computational prosthetic socket design. This type of framework requires realistic patient-specific limb geometry and constitutive properties. In recent studies, indentations and inverse FEA with MRI-derived 3D patient geometries were used for constitutive parameter identification. However, long computational times and use of specialized equipment presents challenges for clinical, deployment. In this study, we present a novel approach for constitutive parameter identification using a combination of FEA, ultrasound indentation, and shear wave elastography. Local shear modulus measurement using elastography during an ultrasound indentation experiment has particular significance for biomechanical modeling of the residual limb since there are known regional dependencies of soft tissue properties such as varying levels of scarring and atrophy. Beyond prosthesis design, this work has broader implications to the fields of muscle health and monitoring of disease progression., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)
- Published
- 2023
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239. Untethered muscle tracking using magnetomicrometry.
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Taylor CR, Yeon SH, Clark WH, Clarrissimeaux EG, O'Donnell MK, Roberts TJ, and Herr HM
- Abstract
Muscle tissue drives nearly all movement in the animal kingdom, providing power, mobility, and dexterity. Technologies for measuring muscle tissue motion, such as sonomicrometry, fluoromicrometry, and ultrasound, have significantly advanced our understanding of biomechanics. Yet, the field lacks the ability to monitor muscle tissue motion for animal behavior outside the lab. Towards addressing this issue, we previously introduced magnetomicrometry, a method that uses magnetic beads to wirelessly monitor muscle tissue length changes, and we validated magnetomicrometry via tightly-controlled in situ testing. In this study we validate the accuracy of magnetomicrometry against fluoromicrometry during untethered running in an in vivo turkey model. We demonstrate real-time muscle tissue length tracking of the freely-moving turkeys executing various motor activities, including ramp ascent and descent, vertical ascent and descent, and free roaming movement. Given the demonstrated capacity of magnetomicrometry to track muscle movement in untethered animals, we feel that this technique will enable new scientific explorations and an improved understanding of muscle function., Competing Interests: CT, SY, and HH have filed patents on the magnetomicrometry concept entitled “Method for neuromechanical and neuroelectromagnetic mitigation of limb pathology” (patent WO2019074950A1) and on implementation strategies for magnetomicrometry entitled “Magnetomicrometric advances in robotic control” (US pending patent 63/104942). The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Taylor, Yeon, Clark, Clarrissimeaux, O’Donnell, Roberts and Herr.)
- Published
- 2022
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240. Clinical viability of magnetic bead implants in muscle.
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Taylor CR, Clark WH, Clarrissimeaux EG, Yeon SH, Carty MJ, Lipsitz SR, Bronson RT, Roberts TJ, and Herr HM
- Abstract
Human movement is accomplished through muscle contraction, yet there does not exist a portable system capable of monitoring muscle length changes in real time. To address this limitation, we previously introduced magnetomicrometry, a minimally-invasive tracking technique comprising two implanted magnetic beads in muscle and a magnetic field sensor array positioned on the body's surface adjacent the implanted beads. The implant system comprises a pair of spherical magnetic beads, each with a first coating of nickel-copper-nickel and an outer coating of Parylene C. In parallel work, we demonstrate submillimeter accuracy of magnetic bead tracking for muscle contractions in an untethered freely-roaming avian model. Here, we address the clinical viability of magnetomicrometry. Using a specialized device to insert magnetic beads into muscle in avian and lagomorph models, we collect data to assess gait metrics, bead migration, and bead biocompatibility. For these animal models, we find no gait differences post-versus pre-implantation, and bead migration towards one another within muscle does not occur for initial bead separation distances greater than 3 cm. Further, using extensive biocompatibility testing, the implants are shown to be non-irritant, non-cytotoxic, non-allergenic, and non-irritating. Our cumulative results lend support for the viability of these magnetic bead implants for implantation in human muscle. We thus anticipate their imminent use in human-machine interfaces, such as in control of prostheses and exoskeletons and in closed-loop neuroprosthetics to aid recovery from neurological disorders., Competing Interests: CT, SY, and HH have filed patents on the magnetomicrometry concept entitled “Method for neuromechanical and neuroelectromagnetic mitigation of limb pathology” (patent WO2019074950A1) and on implementation strategies for magnetomicrometry entitled “Magnetomicrometric advances in robotic control” (US pending patent 63/104942). The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Taylor, Clark, Clarrissimeaux, Yeon, Carty, Lipsitz, Bronson, Roberts and Herr.)
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- 2022
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241. Erratum: Publisher Correction: Agonist-antagonist muscle strain in the residual limb preserves motor control and perception after amputation.
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Song H, Israel EA, Gutierrez-Arango S, Teng AC, Srinivasan SS, Freed LE, and Herr HM
- Abstract
[This corrects the article DOI: 10.1038/s43856-022-00162-z.]., (© The Author(s) 2022.)
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- 2022
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242. Agonist-antagonist muscle strain in the residual limb preserves motor control and perception after amputation.
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Song H, Israel EA, Gutierrez-Arango S, Teng AC, Srinivasan SS, Freed LE, and Herr HM
- Abstract
Background: Elucidating underlying mechanisms in subject-specific motor control and perception after amputation could guide development of advanced surgical and neuroprosthetic technologies. In this study, relationships between preserved agonist-antagonist muscle strain within the residual limb and preserved motor control and perception capacity are investigated., Methods: Fourteen persons with unilateral transtibial amputations spanning a range of ages, etiologies, and surgical procedures underwent evaluations involving free-space mirrored motions of their lower limbs. Research has shown that varied motor control in biologically intact limbs is executed by the activation of muscle synergies. Here, we assess the naturalness of phantom joint motor control postamputation based on extracted muscle synergies and their activation profiles. Muscle synergy extraction, degree of agonist-antagonist muscle strain, and perception capacity are estimated from electromyography, ultrasonography, and goniometry, respectively., Results: Here, we show significant positive correlations ( P < 0.005-0.05) between sensorimotor responses and residual limb agonist-antagonist muscle strain. Identified trends indicate that preserving even 20-26% of agonist-antagonist muscle strain within the residuum compared to a biologically intact limb is effective in preserving natural motor control postamputation, though preserving limb perception capacity requires more (61%) agonist-antagonist muscle strain preservation., Conclusions: The results suggest that agonist-antagonist muscle strain is a characteristic, readily ascertainable residual limb structural feature that can help explain variability in amputation outcome, and agonist-antagonist muscle strain preserving surgical amputation strategies are one way to enable more effective and biomimetic sensorimotor control postamputation., Competing Interests: Competing interestsThe authors declare no competing interests., (© The Author(s) 2022.)
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- 2022
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243. A cutaneous mechanoneural interface for neuroprosthetic feedback.
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S Srinivasan S and M Herr H
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- Afferent Pathways physiology, Animals, Electric Stimulation, Feedback, Rats, Muscles, Skin
- Abstract
Amputation destroys sensory end organs and does not provide an anatomical interface for cutaneous neuroprosthetic feedback. Here, we report the design and a biomechanical and electrophysiological evaluation of the cutaneous mechanoneural interface consisting of an afferent neural system that comprises a muscle actuator coupled to a natively pedicled skin flap in a cuff-like architecture. Muscle is actuated through electrical stimulation to induce strains or oscillatory vibrations on the skin flap that are proportional to a desired contact duration or contact pressure. In rat hindlimbs, the mechanoneural interface elicited native dermal mechanotransducers to generate at least four levels of graded contact and eight distinct vibratory afferents that were not significantly different from analogous mechanical stimulation of intact skin. The application of different patterns of electrical stimulation independently engaged slowly adapting and rapidly adapting mechanotransducers, and recreated an array of cutaneous sensations. The cutaneous mechanoneural interface can be integrated with current prosthetic technologies for tactile feedback., (© 2021. The Author(s), under exclusive licence to Springer Nature Limited.)
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- 2022
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244. The Agonist-antagonist Myoneural Interface.
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Herr H and Carty MJ
- Abstract
Scientist and technologist have long sought to advance limb prostheses that connect directly to the peripheral nervous system, enabling a person with amputation to volitionally control synthetic actuators that move, stiffen and power the prosthesis, as well as to experience natural afferent sensations from the prosthesis. Recently, the agonist-antagonist myoneural interface (AMI) was developed, a mechanoneural transduction architecture and neural interface system designed to provide persons with amputation improved muscle-tendon proprioception and neuroprosthetic control. In this paper, we provide an overview of the AMI, including its conceptual framing and pre-clinical science, surgical techniques for its construction, and clinical efficacy related to pain mitigation, phantom limb range of motion, fascicle dynamics, central brain proprioceptive sensorimotor preservation, and prosthetic controllability. Following this broad overview, we end with a discussion of current limitations of the AMI and potential resolutions to such challenges.
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- 2021
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245. Rejecting Impulse Artifacts from Surface EMG Signals using Real-time Cumulative Histogram Filtering.
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Yeon SH and Herr HM
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- Algorithms, Electromyography, Artifacts, Signal Processing, Computer-Assisted
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This paper presents a cumulative histogram filtering (CHF) algorithm to filter impulsive artifacts within surface electromyograhy (sEMG) signal for time-domain signal feature extraction. The proposed CHF algorithm filters sEMG signals by extracting a continuous subset of amplitude-sorted values within a real-time window of measured samples using information about the probabilistic distribution of sEMG amplitude. For real-time deployment of the proposed CHF algorithm on an embedded computing platform, we also present an efficient, iterative implementation of the proposed algorithm. The proposed CHF algorithm was evaluated on synthetic impulse artifacts superimposed upon undisturbed sEMG recorded from a subject with transtibial amputation. Results suggest that the CHF algorithm effectively suppresses the simulated impulse artifacts while preserving a minimum signal-to-noise ratio of 95% and an average Pearson correlation of 0.99 compared to the undisturbed sEMG recordings.
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- 2021
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246. Spatiotemporally Synchronized Surface EMG and Ultrasonography Measurement Using a Flexible and Low-Profile EMG Electrode.
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Yeon SH, Song H, and Herr HM
- Subjects
- Electrodes, Electromyography, Humans, Ultrasonography, Muscle, Skeletal diagnostic imaging, Musculoskeletal Physiological Phenomena
- Abstract
The temporally synchronized recording of muscle activity and fascicle dynamics is essential in understanding the neurophysiology of human motor control which could promote developments of effective rehabilitation strategies and assistive technologies. Surface electromyography (sEMG) and ultrasonography provide easy-to-use, low-cost, and noninvasive modalities to assess muscle activity and fascicle dynamics, and have been widely used in both clinical and lab settings. However, due to size of these sensors and limited skin surface area, it is extremely challenging to collect data from a muscle of interest in a spatially as well as temporally synchronized manner. Here, we introduce a low-cost, noninvasive flexible electrode that provides high quality sEMG recording, while also enabling spatiotemporally synchronized ultrasonography recordings. The proposed method was verified by comparing ultrasonography of a phantom and a tibialis anterior (TA) muscle during dorsiflexion and plantarflexion with and without the electrode acutely placed under an ultrasound probe. Our results show no significant artifact in ultrasonography from both the phantom and TA fascicle strains due to the presence of the electrode, demonstrating the capability of spatiotemporally synchronized sEMG and ultrasonography recording.
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- 2021
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247. Acquisition of Surface EMG Using Flexible and Low-Profile Electrodes for Lower Extremity Neuroprosthetic Control.
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Yeon SH, Shu T, Song H, Hsieh TH, Qiao J, Rogers EA, Gutierrez-Arango S, Israel E, Freed LE, and Herr HM
- Abstract
For persons with lower extremity (LE) amputation, acquisition of surface electromyography (sEMG) from within the prosthetic socket remains a significant challenge due to the dynamic loads experienced during the gait cycle. However, these signals are critical for both understanding the clinical effects of LE amputation and determining the desired control trajectories of active LE prostheses. Current solutions for collecting within-socket sEMG are generally (i) incompatible with a subject's prescribed prosthetic socket and liners, (ii) uncomfortable, and (iii) expensive. This study presents an alternative within-socket sEMG acquisition paradigm using a novel flexible and low-profile electrode. First, the practical performance of this Sub-Liner Interface for Prosthetics (SLIP) electrode is compared to that of commercial Ag/AgCl electrodes within a cohort of subjects without amputation. Then, the corresponding SLIP electrode sEMG acquisition paradigm is implemented in a single subject with unilateral transtibial amputation performing unconstrained movements and walking on level ground. Finally, a quantitative questionnaire characterizes subjective comfort for SLIP electrode and commercial Ag/AgCl electrode instrumentation setups. Quantitative analyses suggest comparable signal qualities between SLIP and Ag/AgCl electrodes while qualitative analyses suggest the feasibility of using the SLIP electrode for real-time sEMG data collection from load-bearing, ambulatory subjects with LE amputation.
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- 2021
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248. The Agonist-Antagonist Myoneural Interface.
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Carty MJ and Herr HM
- Subjects
- Amputation, Surgical, Humans, Proprioception, Artificial Limbs
- Abstract
The agonist-antagonist myoneural interface is a novel surgical construct and neural interfacing approach designed to augment volitional control of adapted prostheses, preserve proprioception, and prevent limb atrophy in the setting of limb amputation., Competing Interests: Disclosure Dr M.J. Carty and Dr H.M. Herr both currently receive grant income from the DARPA Haptix Program (W911NF-17-2-0043), CDMRP (PRORP-CTA OR160165A; PRORP-CTA OR170384; PRORP-CTA OR180114), Defense Medical Research and Development Program (W81XWH-19-1-0151), and the NIH (1R01HD097135-01). The authors have 2 submitted patents on the AMI and its application to prosthetic control. Funded by:DOD. Grant number(s):CDMRP/PRORP OR160165; CDMRP/PRORP OR170384; CDMRP/PRORP OR180114., (Copyright © 2021 Elsevier Inc. All rights reserved.)
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- 2021
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249. Reinventing Extremity Amputation in the Era of Functional Limb Restoration.
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Herr HM, Clites TR, Srinivasan S, Talbot SG, Dumanian GA, Cederna PS, and Carty MJ
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- Humans, Amputation, Surgical, Artificial Limbs, Limb Salvage, Vascularized Composite Allotransplantation
- Abstract
Background: Recent progress in biomechatronics and vascularized composite allotransplantation have occurred in the absence of congruent advancements in the surgical approaches generally utilized for limb amputation. Consideration of these advances, as well as of both novel and time-honored reconstructive surgical techniques, argues for a fundamental reframing of the way in which amputation procedures should be performed., Methods: We review sentinel developments in external prosthetic limb technology and limb transplantation, in addition to standard and emerging reconstructive surgical techniques relevant to limb modification, and then propose a new paradigm for limb amputation., Results: An approach to limb amputation based on the availability of native tissues is proposed, with the intent of maximizing limb function, limiting neuropathic pain, restoring limb perception/proprioception and mitigating limb atrophy., Conclusions: We propose a reinvention of the manner in which limb amputations are performed, framed in the context of time-tested reconstructive techniques, as well as novel, state-of-the-art surgical procedures. Implementation of the proposed techniques in the acute setting has the potential to elevate advanced limb replacement strategies to a clinical solution that perhaps exceeds what is possible through traditional surgical approaches to limb salvage. We therefore argue that amputation, performed with the intent of optimizing the residuum for interaction with either a bionic or a transplanted limb, should be viewed not as a surgical failure, but as an alternative form of limb reconstruction., Competing Interests: The authors report no conflicts of interest., (Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.)
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- 2021
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250. An Ankle-Foot Prosthesis for Rock Climbing Augmentation.
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Rogers EA, Carney ME, Yeon SH, Clites TR, Solav D, and Herr HM
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- Ankle Joint, Biomechanical Phenomena, Humans, Prosthesis Design, Range of Motion, Articular, Ankle, Artificial Limbs
- Abstract
This research presents the design and preliminary evaluation of an electromyographically (EMG) controlled 2-degree-of-freedom (DOF) ankle-foot prosthesis designed to enhance rock climbing ability in persons with transtibial amputation. The prosthesis comprises motorized ankle and subtalar joints, and is capable of emulating some key biomechanical behaviors exhibited by the ankle-foot complex during rock climbing maneuvers. The free space motion of the device is volitionally controlled via input from EMG surface electrodes embedded in a custom silicone liner worn on the residual limb. The device range of motion is 0.29 radians of each dorsiflexion and plantar flexion, and 0.39 radians each of inversion and eversion. Preliminary evaluation of the device was conducted, validating the system mass of 1292 grams, build height of 250 mm, joint velocity of 2.18 radians/second, settling time of 120 milliseconds, and steady state error of 0.008 radians. Clinical evaluation of the device was performed during a preliminary study with one subject with transtibial amputation. Joint angles of the ankle-foot, knee, and hip were measured during rock climbing with the robotic prosthesis and with a traditional passive prosthesis. We found that the robotic prosthesis increases the range of achieved ankle and subtalar positions compared to a standard passive prosthesis. In addition, maximum knee flexion and hip flexion angles are decreased while climbing with the robotic prosthesis. These results suggest that a lightweight, actuated, 2-DOF EMG-controlled robotic ankle-foot prosthesis can improve ankle and subtalar range of motion and climbing biomechanical function.
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- 2021
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