A Dual Actuated Hand Exoskeleton

Improving Force Transmission

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Abstract

For patients with a hand disability, hand exoskeletons can improve their ability to perform activities of daily living.
Its complicating that on the hand little space is available to build an exoskeleton. So, moment arms of actuators must be small. This complicates generating adequate moments. Strong actuators may be a solution, but they add weight, which should be minimized for comfort. The goal of this thesis is to design a proof of concept that improves force output, considering weight and size criteria.
The proof of concept divides the function of the exoskeleton into two phases that work one after the other. In the first phase the fingers flex to encapsulate an object, in the second phase force is applied. Each phase has an actuator that suits its requirements.
Results show that force output equals 5.087 [N], while the system weights 49.9 [g]. This equals a force-to-weight ratio of 102 [N/kg].
Force output was lower than theorized due to a variety of reasons and did not meet the set criteria of 10 [N]. The criteria of size were not met at the dorsal side of the proximal phalanx. The criteria were 20 [mm] extrusion, 27 [mm] was the end result. Both failures are expected to be solvable. It is concluded that with updates, the design can improve force output while maintaining a small and lightweight design.