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

preprint
posted on 09.11.2020, 15:02 by Sarah Hood, Lukas Gabert, Tommaso Lenzi
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.

Funding

NRI: INT: COLLAB: Muscle Ultrasound Sensing for Intuitive Control of Robotic Leg Prostheses

Directorate for Engineering

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Lightweight Powered Prosthesis for above-knee amputees

National Institute of Child Health and Human Development

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History

Email Address of Submitting Author

sarah.hood@utah.edu

ORCID of Submitting Author

0000-0001-8304-1884

Submitting Author's Institution

University of Utah

Submitting Author's Country

United States of America

Exports

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