Dynamic KAFOs are developed to recover the normal walking ability during both stance and swing phases. Three types of dynamic KAFOs have been reported in the literature. Various actuation mechanisms including spring, pneumatic and hydraulic systems have been used. These devices can improve walking disability and compensate lower leg muscle deficiency. However, they are bulky, in some cases need complex control systems and do not recreate the normal gait pattern. These shortcomings have limited the application of dynamic KAFOs in daily life. The purpose of this paper is to develop a novel knee actuator for a dynamic KAFO that is actuated easily by employing shape memory materials. Such an actuation system makes the KAFO lightweight and has a greater potential to restore the normal gait. Torsional superelastic alloys are used in this actuator in order to match the stiffness of the knee joint of the KAFO with that of a normal knee joint during the walking gait cycle. There are two distinct parts in the knee actuator, acting independently to mimic the two phases of the gait cycle. One engages only in the stance phase and the other works in the swing phase. Each part is developed by combining a superelastic rod and a stiff rotary spring, in series. According to numerical simulation, such combination reproduces the varying knee stiffness during the whole walking gait. Also mechanical experiments have been conducted to further verify the conceptual design. The simulation and experimental results show that the actuator is able to reproduce the stiffness of the normal knee joint during the gait cycle.
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ASME 2014 Conference on Smart Materials, Adaptive Structures and Intelligent Systems
September 8–10, 2014
Newport, Rhode Island, USA
Conference Sponsors:
- Aerospace Division
ISBN:
978-0-7918-4615-5
PROCEEDINGS PAPER
Design and Evaluation of a Knee Actuator for a Dynamic Knee-Ankle-Foot Orthosis
Mohammad Elahinia,
Mohammad Elahinia
University of Toledo, Toledo, OH
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Mohamed Samir Hefzy
Mohamed Samir Hefzy
University of Toledo, Toledo, OH
Search for other works by this author on:
Feng Tian
University of Toledo, Toledo, OH
Mohammad Elahinia
University of Toledo, Toledo, OH
Mohamed Samir Hefzy
University of Toledo, Toledo, OH
Paper No:
SMASIS2014-7605, V002T06A013; 5 pages
Published Online:
December 8, 2014
Citation
Tian, F, Elahinia, M, & Hefzy, MS. "Design and Evaluation of a Knee Actuator for a Dynamic Knee-Ankle-Foot Orthosis." Proceedings of the ASME 2014 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. Volume 2: Mechanics and Behavior of Active Materials; Integrated System Design and Implementation; Bioinspired Smart Materials and Systems; Energy Harvesting. Newport, Rhode Island, USA. September 8–10, 2014. V002T06A013. ASME. https://doi.org/10.1115/SMASIS2014-7605
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