  Fully wearable hand rehabilitation and assistive devices could extend
training and improve quality of life for patients affected by hand impairments.
However, such devices must deliver meaningful manipulation capabilities in a
small and lightweight package. In this context, this paper investigates the
capability of single-actuator devices to assist whole-hand movement patterns
through a network of exotendons. Our prototypes combine a single linear
actuator (mounted on a forearm splint) with a network of exotendons (routed on
the surface of a soft glove). We investigated two possible tendon network
configurations: one that produces full finger extension (overcoming flexor
spasticity), and one that combines proximal flexion with distal extension at
each finger. In experiments with stroke survivors, we measured the force levels
needed to overcome various levels of spasticity and open the hand for grasping
using the first of these configurations, and qualitatively demonstrated the
ability to execute fingertip grasps using the second. Our results support the
feasibility of developing future wearable devices able to assist a range of
manipulation tasks.
