Design Models and Performance Analysis for a Novel Shape Memory Alloy-Actuated Wearable Hand Exoskeleton for Rehabilitation

This letter presents a comprehensive analysis of an innovative wearable hand exoskeleton actuated by Shape Memory Alloy (SMA) wires for rehabilitation. The study covers the design, simulation, and experimental validation of a self-contained system with SMA actuators directly attached to the exoskeleton near the fingers. Numerical models to describe the exoskeleton and phalanx movements are proposed. Non-invasive test, such as image tracking, validated these models, showing strong correlation between theoretical predictions and prototype behavior. Key results include the significant impact of hand interaction on system performance. Tests, also, depict the correlation between electrical parameters, displacement and wire contraction, and confirm safe operational temperatures. The preliminary tests suggest potential for new control strategies based on electrical resistance. This work not only validates the accuracy of our models but also demonstrates the exoskeleton's efficacy in preserving natural hand motion. The integration of experimental and numerical results advances the understanding of SMA-actuated exoskeletons, enhancing their design optimization and applicability in hand rehabilitation. These preliminary study demonstrate the feasibility for future refinements and validation in specific rehabilitation exercises.