A Soft Assistive Device for Elbow Effort-Compensation

The use of assistive technologies in industrial
environments to improve human ergonomics and comfort in
repetitive and high effort tasks have increased considerably
in the last decade. Predominantly, the goal is to provide
additional physical support through lightweight and wearable
devices, without posing major constraints to the human body
movements. Towards achieving this objective, in this work we
present a novel actuation mechanism for a soft assistive device,
by taking into account the human elbow torque-angle profile.
The proposed design integrates a single motor coupled with
an elastic bungee and a cam-spool mechanism to enable energy
exchange during the elbow flexion movement, while allowing for
free-motions during the extension of the joint. A cable-driven
transmission with passive elastic attachments is employed to
implement compliant couplings with the wearer and to achieve
easy donning/doffing. Experiments are conducted on two 3D
printed functional prototypes. Results suggest that the assistive
elbow torque is effectively transmitted with an average 90%
success for balancing a 5N payload, and the free-motion range
of 108 is measured for both flexion and extension.