  Wearable robotic devices have potential to assist and protect their users.
Toward design of a Smart Helmet, this article examines the effectiveness of
audio and visual warnings to help participants brace for impacts. A user study
examines different warnings and impacts applied to users while running.
Perturbation forces scaled to user mass are applied from different directions
and user displacement is measured to characterize effectiveness of the warning.
This is accomplished using the TreadPort Active Wind Tunnel adapted to deliver
forward, rearward, right, or left perturbation forces at precise moments during
the locomotor cycle. The article presents an overview of the system and
demonstrates the ability to precisely deliver consistent warnings and
perturbations during gait. User study results highlight effectiveness of visual
and audio warnings to help users brace for impact, resulting in guidelines that
will inform future human-robot warning systems.
