Accidents caused by users who use their smartphone while walking become a social problem in Japan.
Most of cell-phone carriers also see them as a problem and try to distribute applications that disable
the manipulation of their smartphones by using their sensor data.
However, it is certainly useful for users to use smatphones while walking.
In this paper, we propose a collision avoidance device to be attached to smartphones.
The device detects people and obstacles and provides light, vibration, or attracting force signals for users
so that they can safely avoid obstacles while walking.