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A concept design of an adaptive tendon driven mechanism for active soft hand Orthosis.
Bruno Cardoso Godinho Lourenço * 1, 2 , Vitorino Biazi Neto 1 , Rafhael Milanezi de Andrade 1
1  Laboratory of Robotics and Biomechanics, Department of Mechanical Engineering, Universidade Federal do Espírito Santo, BR
2  PET-Mecância UFES, Department of Mechanical Engineering, Universidade Federal do Espírito Santo, BR

10.3390/IeCAT2020-08504 (registering DOI)
Abstract:

The Hands exert a vital role since the simplest to complex tasks and lose the ability to make those movements, which is usually caused by spinal cord injury or stroke impacts dramatically the quality of life. In order to counteract this problem, several assisting devices have been proposed, but they still present several usage limitations. The marketable orthoses are generally either the static type or over-expensive active orthosis that cannot perform the same degrees of freedom (DoF) that a hand can do. This paper presents a conceptual design of a tendon driven mechanism for hand’s active orthosis. This study is a part of an effort to develop an effective and low-cost hand’s orthosis for people with hand paralysis. The tendon design proposed was thought to comply with some requisitions, how lightness, and low volume, as well as fit with the biomechanical constraints of human tendons to enable a comfortable use. The mechanism employs small cursors on the phalanges to allow the tendons to run on the dorsal side and by both sides of the fingers, allowing 2 DoF for each finger, one extra tendon enlarges the hands’ adduction nuances. It is simple enough to execute the flexion and extension movements (the movements most used in daily actives) using one single DC actuator for one DoF, reducing costs, or expanding it, with more DC actuators to enable more natural hand coordination. This system of actuation is suitable to create soft exoskeletons for hands easily embedded into 3D printed parts, which could be merged over statics thermoplastic orthosis. The final orthosis design allows dexterous finger movements and force to grasp objects and perform tasks comfortably.

Keywords: Tendon-driven; wearable device; grasping power assistance; soft-exoskeleton; actuated hand.
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