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Hsieh TH, Song H, Shu T, Qiao J, Yeon SH, Carney M, Mooney L, Duval JF, Herr H. Design, Characterization, and Preliminary Assessment of a Two-Degree-of-Freedom Powered Ankle-Foot Prosthesis. Biomimetics (Basel) 2024; 9:76. [PMID: 38392122 PMCID: PMC10886942 DOI: 10.3390/biomimetics9020076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2023] [Revised: 01/22/2024] [Accepted: 01/22/2024] [Indexed: 02/24/2024] Open
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.
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Affiliation(s)
- Tsung-Han Hsieh
- K. Lisa Yang Center for Bionics, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
- Department of Media Arts and Sciences, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Hyungeun Song
- K. Lisa Yang Center for Bionics, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
- Department of Media Arts and Sciences, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Tony Shu
- K. Lisa Yang Center for Bionics, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
- Department of Media Arts and Sciences, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Junqing Qiao
- K. Lisa Yang Center for Bionics, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
- Department of Media Arts and Sciences, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Seong Ho Yeon
- K. Lisa Yang Center for Bionics, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
- Department of Media Arts and Sciences, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Matthew Carney
- Department of Media Arts and Sciences, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Luke Mooney
- Dephy Inc., 80 Central St, Suite 125, Boxborough, MA 01719, USA
| | - Jean-François Duval
- Department of Media Arts and Sciences, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Hugh Herr
- K. Lisa Yang Center for Bionics, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
- Department of Media Arts and Sciences, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
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2
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Ramadurai S, Jeong H, Kim M. Predicting the metabolic cost of exoskeleton-assisted squatting using foot pressure features and machine learning. Front Robot AI 2023; 10:1166248. [PMID: 37151375 PMCID: PMC10154631 DOI: 10.3389/frobt.2023.1166248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Accepted: 04/05/2023] [Indexed: 05/09/2023] Open
Abstract
Introduction: Recent studies found that wearable exoskeletons can reduce physical effort and fatigue during squatting. In particular, subject-specific assistance helped to significantly reduce physical effort, shown by reduced metabolic cost, using human-in-the-loop optimization of the exoskeleton parameters. However, measuring metabolic cost using respiratory data has limitations, such as long estimation times, presence of noise, and user discomfort. A recent study suggests that foot contact forces can address those challenges and be used as an alternative metric to the metabolic cost to personalize wearable robot assistance during walking. Methods: In this study, we propose that foot center of pressure (CoP) features can be used to estimate the metabolic cost of squatting using a machine learning method. Five subjects' foot pressure and metabolic cost data were collected as they performed squats with an ankle exoskeleton at different assistance conditions in our prior study. In this study, we extracted statistical features from the CoP squat trajectories and fed them as input to a random forest model, with the metabolic cost as the output. Results: The model predicted the metabolic cost with a mean error of 0.55 W/kg on unseen test data, with a high correlation (r = 0.89, p < 0.01) between the true and predicted cost. The features of the CoP trajectory in the medial-lateral direction of the foot (xCoP), which relate to ankle eversion-inversion, were found to be important and highly correlated with metabolic cost. Conclusion: Our findings indicate that increased ankle eversion (outward roll of the ankle), which reflects a suboptimal squatting strategy, results in higher metabolic cost. Higher ankle eversion has been linked with the etiology of chronic lower limb injuries. Hence, a CoP-based cost function in human-in-the-loop optimization could offer several advantages, such as reduced estimation time, injury risk mitigation, and better user comfort.
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Affiliation(s)
- Sruthi Ramadurai
- Rehabilitation Robotics Laboratory, Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL, United States
| | - Heejin Jeong
- The Polytechnic School, Ira A. Fulton Schools of Engineering, Arizona State University, Mesa, AZ, United States
- *Correspondence: Myunghee Kim, ; Heejin Jeong,
| | - Myunghee Kim
- Rehabilitation Robotics Laboratory, Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL, United States
- *Correspondence: Myunghee Kim, ; Heejin Jeong,
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3
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Naseri A, Liu M, Lee IC, Liu W, Huang H(H. Characterizing Prosthesis Control Fault during Human-Prosthesis Interactive Walking Using Intrinsic Sensors. IEEE Robot Autom Lett 2022; 7:8307-8314. [PMID: 36713301 PMCID: PMC9881473 DOI: 10.1109/lra.2022.3186503] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The physical interactions between wearable lower limb robots and humans have been investigated to inform effective robot design for walking augmentation. However, human-robot interactions when internal faults occur within robots have not been systematically reported, but it is essential to improve the robustness of robotic devices and ensure the user's safety. This paper aims to (1) present a methodology to characterize the behavior of the robotic transfemoral prosthesis as an effective wearable robot platform while interacting with the users in the presence of internal faults, and (2) identify the potential data sources for accurate detection of the prosthesis fault. We first obtained the human perceived response in terms of their walking stability when the prosthesis control fault (inappropriate intrinsic control output/command) was emulated/applied in level-ground walking. Then the measurements and their features, obtained from the transfemoral prosthesis, were examined for the emulated faults that elicited a sense of instability in human users. The optimal features that contributed the most in separating faulty interaction from the normal walking condition were determined using two machine-learning-based approaches: One-Class Support Vector Machine (OCSVM) and Mahalanobis Distance (MD) classifier. The OCSVM anomaly detector could achieve an average sensitivity of 85.7 % and an average false alarm rate of 1.7 % with a reasonable detecting time of 147.6 ms for detecting emulated control errors among all subjects. The result demonstrates the potential of using machine-learning-based schemes in identifying prosthesis control faults based on intrinsic sensors on the prosthesis. This study presents a procedure to study human-robot fault tolerance and inform the future design of robust prosthesis control.
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Affiliation(s)
- Amirreza Naseri
- UNC/NCSU Department of Biomedical Engineering, NC State University, Raleigh, NC 27695 USA,University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 USA
| | - Ming Liu
- UNC/NCSU Department of Biomedical Engineering, NC State University, Raleigh, NC 27695 USA,University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 USA
| | - I-Chieh Lee
- UNC/NCSU Department of Biomedical Engineering, NC State University, Raleigh, NC 27695 USA,University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 USA
| | - Wentao Liu
- UNC/NCSU Department of Biomedical Engineering, NC State University, Raleigh, NC 27695 USA,University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 USA
| | - Helen (He) Huang
- UNC/NCSU Department of Biomedical Engineering, NC State University, Raleigh, NC 27695 USA,University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 USA
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4
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Foot contact forces can be used to personalize a wearable robot during human walking. Sci Rep 2022; 12:10947. [PMID: 35768457 PMCID: PMC9243054 DOI: 10.1038/s41598-022-14776-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Accepted: 06/13/2022] [Indexed: 11/09/2022] Open
Abstract
Individuals with below-knee amputation (BKA) experience increased physical effort when walking, and the use of a robotic ankle-foot prosthesis (AFP) can reduce such effort. The walking effort could be further reduced if the robot is personalized to the wearer using human-in-the-loop (HIL) optimization of wearable robot parameters. The conventional physiological measurement, however, requires a long estimation time, hampering real-time optimization due to the limited experimental time budget. This study hypothesized that a function of foot contact force, the symmetric foot force-time integral (FFTI), could be used as a cost function for HIL optimization to rapidly estimate the physical effort of walking. We found that the new cost function presents a reasonable correlation with measured metabolic cost. When we employed the new cost function in HIL ankle-foot prosthesis stiffness parameter optimization, 8 individuals with simulated amputation reduced their metabolic cost of walking, greater than 15% (p < 0.02), compared to the weight-based and control-off conditions. The symmetry cost using the FFTI percentage was lower for the optimal condition, compared to all other conditions (p < 0.05). This study suggests that foot force-time integral symmetry using foot pressure sensors can be used as a cost function when optimizing a wearable robot parameter.
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5
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Ziemnicki DM, Caputo JM, McDonald KA, Zelik KE. Development and Evaluation of a Prosthetic Ankle Emulator With an Artificial Soleus and Gastrocnemius. J Med Device 2021. [DOI: 10.1115/1.4052518] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Abstract
In individuals with transtibial limb loss, a contributing factor to mobility-related challenges is the disruption of biological calf muscle function due to transection of the soleus and gastrocnemius. Powered prosthetic ankles can restore primary function of the mono-articular soleus muscle, which contributes to ankle plantarflexion. In effect, a powered ankle acts like an artificial soleus (AS). However, the biarticular gastrocnemius connection that simultaneously contributes to ankle plantarflexion and knee flexion torques remains missing, and there are currently no commercially available prosthetic ankles that incorporate an artificial gastrocnemius (AG). The goal of this work is to describe the design of a novel emulator capable of independently controlling artificial soleus and gastrocnemius behaviors for transtibial prosthesis users during walking. To evaluate the emulator's efficacy in controlling the artificial gastrocnemius behaviors, a case series walking study was conducted with four transtibial prosthesis users. Data from this case series showed that the emulator exhibits low resistance to the user's leg swing, low hysteresis during passive spring emulation, and accurate force tracking for a range of artificial soleus and gastrocnemius behaviors. The emulator presented in this paper is versatile and can facilitate experiments studying the effects of various artificial soleus and gastrocnemius dynamics on gait or other movement tasks. Using this system, it is possible to address existing knowledge gaps and explore a wide range of artificial soleus and gastrocnemius behaviors during gait and potentially other activities of daily living.
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Affiliation(s)
- David M. Ziemnicki
- Department of Mechanical Engineering, Vanderbilt University, 2201 West End Avenue, Nashville, TN 37235
| | - Joshua M. Caputo
- Human Motion Technologies LLC, 630 William Pitt Way U-PARC Building A2, Pittsburgh, PA 15238
| | - Kirsty A. McDonald
- Department of Exercise Physiology, School of Health Sciences, University of New South Wales, Level 2, Wallace Wurth Building, UNSW, Sydney, NSW 2052, Australia
| | - Karl E. Zelik
- Department of Mechanical Engineering, Vanderbilt University, 2201 West End Avenue, Nashville, TN 37235; Department of Biomedical Engineering, Vanderbilt University, 2201 West End Avenue, Nashville, TN 37235; Department of Physical Medicine and Rehabilitation, Vanderbilt University, 2201 West End Avenue, Nashville, TN 37235
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6
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Jang WS, Kim DY, Choi YS, Kim YJ. Self-Contained 2-DOF Ankle-Foot Prosthesis With Low-Inertia Extremity for Agile Walking on Uneven Terrain. IEEE Robot Autom Lett 2021. [DOI: 10.1109/lra.2021.3098931] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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7
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Takeda I, Yasunaga W, Kobayashi S, Tagawa Y, Onodera H. Gait assist brace with double carbon fiber reinforced plastic spring blades to allow ankle joint movement and change in walking direction. Adv Robot 2021. [DOI: 10.1080/01691864.2021.1946422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Iwori Takeda
- Department of Mechanical Systems Engineering, School of Engineering, The University of Tokyo, Bunkyo, Tokyo, Japan
| | - Wataru Yasunaga
- Graduate School of Science and Engineering, Tokyo Metropolitan University, Hachioji, Tokyo, Japan
| | - Satoshi Kobayashi
- Department of Mechanical Systems Engineering, Graduate School of Systems Design, Tokyo Metropolitan University, Hino, Tokyo, Japan
| | - Yusaku Tagawa
- Department of Mechanical Systems Engineering, School of Engineering, The University of Tokyo, Bunkyo, Tokyo, Japan
| | - Hiroshi Onodera
- Department of Mechanical Systems Engineering, School of Engineering, The University of Tokyo, Bunkyo, Tokyo, Japan
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8
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Chen J, Hochstein J, Kim C, Tucker L, Hammel LE, Damiano DL, Bulea TC. A Pediatric Knee Exoskeleton With Real-Time Adaptive Control for Overground Walking in Ambulatory Individuals With Cerebral Palsy. Front Robot AI 2021; 8:702137. [PMID: 34222356 PMCID: PMC8249803 DOI: 10.3389/frobt.2021.702137] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 05/27/2021] [Indexed: 11/13/2022] Open
Abstract
Gait training via a wearable device in children with cerebral palsy (CP) offers the potential to increase therapy dosage and intensity compared to current approaches. Here, we report the design and characterization of a pediatric knee exoskeleton (P.REX) with a microcontroller based multi-layered closed loop control system to provide individualized control capability. Exoskeleton performance was evaluated through benchtop and human subject testing. Step response tests show the averaged 90% rise was 26 ± 0.2 ms for 5 Nm, 22 ± 0.2 ms for 10 Nm, 32 ± 0.4 ms for 15 Nm. Torque bandwidth of P.REX was 12 Hz and output impedance was less than 1.8 Nm with control on (Zero mode). Three different control strategies can be deployed to apply assistance to knee extension: state-based assistance, impedance-based trajectory tracking, and real-time adaptive control. One participant with typical development (TD) and one participant with crouch gait from CP were recruited to evaluate P.REX in overground walking tests. Data from the participant with TD were used to validate control system performance. Kinematic and kinetic data were collected by motion capture and compared to exoskeleton on-board sensors to evaluate control system performance with results demonstrating that the control system functioned as intended. The data from the participant with CP are part of a larger ongoing study. Results for this participant compare walking with P.REX in two control modes: a state-based approach that provided constant knee extension assistance during early stance, mid-stance and late swing (Est+Mst+Lsw mode) and an Adaptive mode providing knee extension assistance proportional to estimated knee moment during stance. Both were well tolerated and significantly improved knee extension compared to walking without extension assistance (Zero mode). There was less reduction in gait speed during use of the adaptive controller, suggesting that it may be more intuitive than state-based constant assistance for this individual. Future work will investigate the effects of exoskeleton assistance during overground gait training in children with neurological disorders and will aim to identify the optimal individualized control strategy for exoskeleton prescription.
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Affiliation(s)
- Ji Chen
- Biomedical Engineering Program, Department of Mechanical Engineering, University of the District of Columbia, Washington, DC, United States
- Rehabilitation Medicine Department, National Institutes of Health Clinical Center, Bethesda, MD, United States
| | - Jon Hochstein
- Rehabilitation Medicine Department, National Institutes of Health Clinical Center, Bethesda, MD, United States
| | - Christina Kim
- Rehabilitation Medicine Department, National Institutes of Health Clinical Center, Bethesda, MD, United States
| | - Luke Tucker
- Rehabilitation Medicine Department, National Institutes of Health Clinical Center, Bethesda, MD, United States
| | - Lauren E. Hammel
- Rehabilitation Medicine Department, National Institutes of Health Clinical Center, Bethesda, MD, United States
| | - Diane L. Damiano
- Rehabilitation Medicine Department, National Institutes of Health Clinical Center, Bethesda, MD, United States
| | - Thomas C. Bulea
- Rehabilitation Medicine Department, National Institutes of Health Clinical Center, Bethesda, MD, United States
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9
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Liu J, Abu Osman NA, Al Kouzbary M, Al Kouzbary H, Abd Razak NA, Shasmin HN, Arifin N. Classification and Comparison of Mechanical Design of Powered Ankle–Foot Prostheses for Transtibial Amputees Developed in the 21st Century: A Systematic Review. J Med Device 2021. [DOI: 10.1115/1.4049437] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Abstract
A systematic review of the mechanical design of powered ankle–foot prostheses developed from 2000 to 2019 was conducted through database and manual searches. A total of ten English and two Chinese databases were searched using the same keywords. Moreover, information on commercialized prostheses was collected through a manual search. A total of 8729 publications were obtained from the database search, and 83 supplementary publications and 49 online product introductions were accumulated through the manual search. A total of 91 powered ankle–foot prostheses were extracted from 159 publications and online information after exclusion. The mechanical design characteristics of the prostheses were described briefly and compared after they were categorized into 11 subclassifications. This review revealed that a considerable number of powered ankle–foot prostheses were developed in the last 20 years. The development of such prostheses was characterized by alternative modes, that is, from pneumatic or hydraulic drivers to motorized drivers and from rigid transmissions to elastic actuators. This review contributes to the comprehensive understanding of current designs, which can benefit the combination of the advantages of and redundancy avoidance in future powered ankle–foot prostheses.
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Affiliation(s)
- Jingjing Liu
- Centre for Applied Biomechanics, Department of Biomedical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur 50603, Malaysia
| | - Noor Azuan Abu Osman
- Centre for Applied Biomechanics, Department of Biomedical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur 50603, Malaysia
| | - Mouaz Al Kouzbary
- Centre for Applied Biomechanics, Department of Biomedical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur 50603, Malaysia
| | - Hamza Al Kouzbary
- Centre for Applied Biomechanics, Department of Biomedical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur 50603, Malaysia
| | - Nasrul Anuar Abd Razak
- Centre for Applied Biomechanics, Department of Biomedical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur 50603, Malaysia
| | - Hanie Nadia Shasmin
- Centre for Applied Biomechanics, Department of Biomedical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur 50603, Malaysia
| | - Nooranida Arifin
- Centre for Applied Biomechanics, Department of Biomedical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur 50603, Malaysia
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10
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Azocar AF, Mooney LM, Duval JF, Simon AM, Hargrove LJ, Rouse EJ. Design and clinical implementation of an open-source bionic leg. Nat Biomed Eng 2020; 4:941-953. [PMID: 33020601 PMCID: PMC7581510 DOI: 10.1038/s41551-020-00619-3] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 08/27/2020] [Indexed: 11/09/2022]
Abstract
In individuals with lower-limb amputations, robotic prostheses can increase walking speed, and reduce energy use, the incidence of falls and the development of secondary complications. However, safe and reliable prosthetic-limb control strategies for robust ambulation in real-world settings remain out of reach, partly because control strategies have been tested with different robotic hardware in constrained laboratory settings. Here, we report the design and clinical implementation of an integrated robotic knee-ankle prosthesis that facilitates the real-world testing of its biomechanics and control strategies. The bionic leg is open source, it includes software for low-level control and for communication with control systems, and its hardware design is customizable, enabling reduction in its mass and cost, improvement in its ease of use and independent operation of the knee and ankle joints. We characterized the electromechanical and thermal performance of the bionic leg in benchtop testing, as well as its kinematics and kinetics in three individuals during walking on level ground, ramps and stairs. The open-source integrated-hardware solution and benchmark data that we provide should help with research and clinical testing of knee-ankle prostheses in real-world environments.
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Affiliation(s)
- Alejandro F Azocar
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, USA.,Robotics Institute, University of Michigan, Ann Arbor, MI, USA
| | | | | | - Ann M Simon
- Center for Bionic Medicine, Shirley Ryan AbilityLab, Chicago, IL, USA.,Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, IL, USA
| | - Levi J Hargrove
- Center for Bionic Medicine, Shirley Ryan AbilityLab, Chicago, IL, USA.,Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, IL, USA.,Department of Biomedical Engineering, Northwestern University, Evanston, IL, USA
| | - Elliott J Rouse
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, USA. .,Robotics Institute, University of Michigan, Ann Arbor, MI, USA.
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11
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Gonabadi AM, Antonellis P, Malcolm P. A System for Simple Robotic Walking Assistance With Linear Impulses at the Center of Mass. IEEE Trans Neural Syst Rehabil Eng 2020; 28:1353-1362. [PMID: 32340953 PMCID: PMC7404782 DOI: 10.1109/tnsre.2020.2988619] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Walking can be simplified as an inverted pendulum motion where both legs generate linear impulses to redirect the center of mass (COM) into every step. In this work, we describe a system to assist walking in a simpler way than exoskeletons by providing linear impulses directly at the COM instead of providing torques at the joints. We developed a novel waist end-effector and high-level controller for an existing cable-robot. The controller allows for the application of cyclic horizontal force profiles with desired magnitudes, timings, and durations based on detection of the step timing. By selecting a lightweight rubber series elastic element with optimal stiffness and carefully tuning the gains of the closed-loop proportional-integral-derivative (PID) controller in a number of single-subject experiments, we were able to reduce the within-step root mean square error between desired and actual forces up to 1.21% of body weight. This level of error is similar or lower compared to the performance of other robotic tethers designed to provide variable or constant forces at the COM. The system can produce force profiles with peaks of up to 15 ± 2% of body weight within a root mean square error (RMSE) of 2.5% body weight. This system could be used to assist patient populations that require levels of assistance that are greater than current exoskeletons and in a way that does not make the user rely on vertical support.
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12
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Antonellis P, Frederick CM, Gonabadi AM, Malcolm P. Modular footwear that partially offsets downhill or uphill grades minimizes the metabolic cost of human walking. ROYAL SOCIETY OPEN SCIENCE 2020; 7:191527. [PMID: 32257319 PMCID: PMC7062060 DOI: 10.1098/rsos.191527] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 12/17/2019] [Indexed: 06/11/2023]
Abstract
Walking on different grades becomes challenging on energetic and muscular levels compared to level walking. While it is not possible to eliminate the cost of raising or lowering the centre of mass (COM), it could be possible to minimize the cost of distal joints with shoes that offset downhill or uphill grades. We investigated the effects of shoe outsole geometry in 10 participants walking at 1 m s-1 on downhill, level and uphill grades. Level shoes minimized metabolic rate during level walking (P second-order effect < 0.001). However, shoes that entirely offset the (overall) treadmill grade did not minimize the metabolic rate of walking on grades: shoes with a +3° (upward) inclination minimized metabolic rate during downhill walking on a -6° grade, and shoes with a -3° (downward) inclination minimized metabolic rate during uphill walking on a +6° grade (P interaction effect = 0.023). Shoe inclination influenced (distal) ankle joint parameters, including soleus muscle activity, ankle moment and work rate, whereas treadmill grade influenced (whole-body) ground reaction force and COM work rate as well as (distal) ankle joint parameters including tibialis anterior and plantarflexor muscle activity, ankle moment and work rate. Similar modular footwear could be used to minimize joint loads or assist with walking on rolling terrain.
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13
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Price MA, Beckerle P, Sup FC. Design Optimization in Lower Limb Prostheses: A Review. IEEE Trans Neural Syst Rehabil Eng 2019; 27:1574-1588. [PMID: 31283485 DOI: 10.1109/tnsre.2019.2927094] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
This paper aims to develop a knowledge base and identify the promising research pathways toward designing lower limb prostheses for optimal biomechanical and clinical outcomes. It is based on the literature search representing the state of the art in the lower limb prosthesis joint design and biomechanical analysis. Current design solutions are organized in terms of fulfilling four key functional roles: body support, propulsion, task flexibility, and loading relief. Biomechanical analyses of these designs reveal that the hypothesized outcomes are not consistently observed. We suggest that these outcomes may be improved by incorporating tools that can predict user performance metrics to optimize the device during the initial design process. We also note that the scope of the solution space of most current designs is limited by focusing on the anthropomorphic design approaches that do not account for the person's altered anatomy post-amputation. The effects of the prosthetic joint behavior on whole-body gait biomechanics and user experience are likewise under-explored. Two research paths to support the goal of better predicting the user outcomes are proposed: experimental parameterization of designs and model-based simulations. However, while work in these areas has introduced promising new possibilities, connecting both to improve real-world performance remains a challenge.
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