Objective:
Providing sensory feedback to the user of the prosthesis is an important challenge
.
The common
approach is to use tactile stimulation, which is easy to implement but requires training and
has
limited
information bandwidth. In
this
study, we
propose
an alternative approach based on
augmented reality
.
Approach:
We have developed the GLIMPS
E,
a
Google Glass
application which connects to the prosthesis via a
Bluetooth interface and renders the prosthesis states
(EMG signals, aperture, force and
contact
)
using
augmented reality (see
-
through display) and sound (bone conduction transducer). The
interface was tested in
healthy subjects that used the prosthesis
with (FB group) and without (NFB group)
feedback
during a modified
clothespins
test that allowed to
vary the difficulty of the task
. The outcome measures were the number of
unsuccessful
tria
ls
,
the
time to accomplish the task
,
and the subjective ratings of the relevance of the feedback.
R
esults:
There was no difference in performance between FB and NFB groups in the case of a simple task
(
basic
, same
-
color
clothespins test
), but the feedback
significantly improved the performance in a more complex
task (
pins of different resistances
). Importantly, the GLIMPSE feedback did not increase the time to accomplish
the task.
Therefore, the supplemental feedback might be useful in the tasks which are
more demanding, and
thereby less likely to benefit from learning and feedforward control. The subjects integrated
the
supplemental
feedback with the intrinsic sources (vision and muscle proprioception), developing their own idiosyncratic
s
trategies
to acco
mplish the task.
Significance:
The present study demonstrate
s
a novel self
-
contained,
ready
-
to
-
deploy,
wearable
feedback
interface
based on
widely
used and readily available
technology
.
The interface was successfully tested
and was
proven to be feasible
an
d functional
ly
benefi
cial
.
The GLIMPSE can be used as a practical solution but also as a
general and flexible instrument to investigate closed
-
loop prosthesis control.