LineChaser a smartphone-based navigation system for blind people to stand in lines.
Standing in lines is difficult for blind people.
It requires two tasks to be completed.
Finding the end of line and following it.
However, it is difficult to determine where the end of a line is without visual sense.
Even if they find it following the line is difficult because blind people has to determine
which way and how long to walk.
To tackle this problem, our Research Goal is to Assist blind people to both find and
follow the end of line using only one smartphone.
Therefore, we introduce a smartphone-based system called LineChaser.
To assist line-standing task, LineChaser uses predetermined map which consists of line information.
It consists of front of a line, width of a line, entrance of a line and where people
might stand in.
First, LineChaser localizes itself in the predetermined map using ar marker.
Based on the localization result, the system navigates user to the entrance of the line.
Then LineChaser instructs the user to walk along the line.
This way, the last person of the line will eventually appear.
While navigating, LineChaser identifies people standing in the line by using both predetermined
map and results of position estimation.
In this case, this blue person is detected as a person standing in the line and this
gray person is detected as a person standing out the line.
The color histogram is used to track the target person out of all person standing in the line.
We distinguish each detected person by comparing each person's color histogram distance.
At last, when the target person is determined, LineChaser instructs user to follow the line,
keeping 1.5m.
LineChaser adopts interface of both audio and vibration.
With audio, the system conveys the direction and distance to notify the user with general
position to move.
LineChaser vibrates when the user is facing the correct direction and when the user should
move.
This is used to notify user with exact orientation and timing.
To assess usability of LineChaser, we conducted user study with 12 blind participants.
We prepared straight and serpentine line.
Participants were asked to find and follow the end of a line using LineChaser.
Here I show the video of experiment.
You can see that the blind participants are able to stand in lines by themselves using
LineChaser.
To evaluate, we measured where and how many times the participants stopped in the in the
line.
We defined ideal position as the place where the participants kept 1.5m and stood in center
of the line.
We defined acceptable positions as the place surrounding ideal position.
As a result, participants found the end of a line within acceptable positions with the
probability of 100% and stopped within ideal position with the probability of 40.2%.
When following the line, participants were able to stop within acceptable positions with
the probability of 90.9% and stopped within ideal position with the probability of 34.7%.
13 failures to stop in acceptable positions can be classified to three reasons.
4 participants were unable to correct their orientation while standing in line.
2 participants did not understand how to use the interface of LineChaser.
Also, 2 failures occurred because localization error of LineChaser accumulated.
We also asked participants to rate confidence when standing in lines with and without LineChaser
with 7 points.
As a result, we found out that participants were significantly confident standing in lines
when using LineChaser.
We also asked participants to rate interface of LineChaser with 7 points.
We found out that participants found it easy to understand the interface of LineChaser.
We obtained a feedback from P03 indicating she found it easier to find the end of line
and was confident following it with LineChaser.
Also, we obtained a feedback from p09 that he used the interface as we designed to.
So, in conclusion, we present LineChaser, the system that assists blind people to both
find and follow the end of line with only one smart phone.
The system first determines line standing people and tracks the target person.
Our future work is to conduct a real-world user study to assess generalizability of LineChaser
in real world environment.