A Compact, Lightweight Robotic Ankle-Foot Prosthesis: Featuring a Powered Polycentric Design

We propose a shared neural control approach combining neural signals from the user's residual limb with robot control to improve functional mobility in individuals with above-knee amputation. The proposed shared neural controller enables subjects to stand up under a variety of conditions, squat, lunge, walk, and seamlessly transition between activities which is not possible with other prostheses or controllers. Further, we show that the proposed shared neural controller reduces muscle effort and increased symmetry during standing up compared to conventional passive prostheses. No other available technology can enable individuals with above-knee amputations to achieve this level of mobility.

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“…The ankle joint is controlled using an impedance-based control strategy [52] with fixed stiffness and damping and variable equilibrium position (…”

Section: A Shared Neural Controlmentioning

confidence: 99%

Stand-Up, Squat, Lunge, and Walk With a Robotic Knee and Ankle Prosthesis Under Shared Neural Control

Hunt

Hood

Lenzi

2021

IEEE Open J. Eng. Med. Biol.

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“…The experiment preparation took place before data collection. The subject donned the Utah Lightweight Leg [17], [29], which is a fully powered, modular, and self-contained knee and ankle prosthesis. A certified prosthetist adjusted the build height of the prosthesis using a standard pylon and ensured proper alignment of the knee and ankle joints.…”

Section: B Human Testingmentioning

confidence: 99%

“…The Utah Lightweight Leg weighs ~2.7 kg including battery and protective covers-approximately half of similar powered prostheses [21]. The ankle-foot module uses a compact, lightweight powered polycentric design, which is contained within a commercially-available foot shell [29] [32]. The powered polycentric mechanism is connected to custom carbon-fiber feet of different sizes to accommodate different subjects.…”

Section: Powered Knee and Ankle Prosthesismentioning

confidence: 99%

Powered Knee and Ankle Prosthesis with Adaptive Control Enables Climbing Stairs with Different Stair Heights, Cadences, and Gait Patterns

Hood¹,

Gabert²,

Lenzi³

2022

Preprint

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Powered prostheses can enable individuals with above-knee amputations to ascend stairs step-over-step. To accomplish this task, available stair ascent controllers impose a pre-defined joint impedance behavior or follow a pre-programmed position trajectory. These control approaches have proved successful in the laboratory. However, they are not robust to changes in stair height or cadence, which is essential for real-world ambulation. Here we present an adaptive stair ascent controller that enables individuals with above-knee amputations to climb stairs of varying stair heights at their preferred cadence and with their preferred gait pattern. We found that modulating the prosthesis knee and ankle position as a function of the user’s thigh in swing provides toe clearance for varying stair heights. In stance, modulating the torque-angle relationship as a function of the prosthesis knee position at foot contact provides sufficient torque assistance for climbing stairs of different heights. Furthermore, the proposed controller enables individuals to climb stairs at their preferred cadence and gait pattern, such as step-by-step, step-over-step, and two-step, similar to able-bodied individuals. We anticipate the proposed control strategy will improve the robustness of powered prostheses to environmental and human variance without the need for expert tuning, machine learning, or direct subject intervention, which may enable powered prostheses to more easily move from the lab to the real-world.

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“…3D printed sockets need careful consideration in material selection in the context of biocompatibility, lightweight, comfortable socket design, design of liners, and its printing. A weight-effective transtibial prosthesis [51] explored uses the polycentric design that weighs 1.32 Kg. The design was in comparison to the commercially available prosthesis of Ottobock but it was in the research phase.…”

Section: Bmentioning

confidence: 99%

Advancements, Trends and Future Prospects of Lower Limb Prosthesis

et al. 2021

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Amputees with lower limb loss need special care during daily life activities to make the movement natural as before amputation. No such work exists covering the main aspects from causes of amputation to the psycho-social impact of the amputees after using the prosthetic device. This review presents for lower limb prosthesis; the study of lower limb amputation, design & development, control strategies & machine learning algorithms, the psycho-social impact of prosthetic users, and design trends in patents. Research articles, review papers, magazines, letters, study reports, surveys, and patents, etc. have been used as sources for this review. Traumatic injuries and different diseases have been found as common causes of amputation. Design & development section illustrates design mechanisms, the categories of passive, active, & semi-active prostheses, an overview of a subset of commercially available prosthetic devices, and 3D printing of the accessories. The control section provides information about control techniques, sensors used, machine learning algorithms, and their key outcomes. Quality of life, phantom limb pain, and psycho-social impact of prosthetic users have been summarized for different countries that are believed to attract the interest of the readers. We have also developed an opensource database "FAKH-50" for patents to emphasize the design trends and advancements in lower limb prostheses from 1970 to 2020. Overall trend analysis determined is in the descending order as the knee (48%) > ankle (28%) > foot (22%) > hip (2%) patents in the current version of our database. The forthcoming section highlights the challenges and prospects of the domain. A mutual observation demands the design of a bio-compatible, lightweight, and economic prosthesis to track the normal human gait by eliminating phantom limb pain. This will empower the amputees to live a quality life in society. This work may be beneficial for researchers, technicians, clinicians, and amputees.INDEX TERMS Causes of amputation, lower limb amputation, lower limb prosthesis, design mechanisms, semi-active prosthesis, human gait cycle.

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A Compact, Lightweight Robotic Ankle-Foot Prosthesis: Featuring a Powered Polycentric Design

Cited by 41 publications

References 52 publications

Stand-Up, Squat, Lunge, and Walk With a Robotic Knee and Ankle Prosthesis Under Shared Neural Control

Stand-Up, Squat, Lunge, and Walk With a Robotic Knee and Ankle Prosthesis Under Shared Neural Control

Powered Knee and Ankle Prosthesis with Adaptive Control Enables Climbing Stairs with Different Stair Heights, Cadences, and Gait Patterns

Advancements, Trends and Future Prospects of Lower Limb Prosthesis

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