  This paper describes a method to convert Microsoft Kinect coordinates into
gait parameters in order to detect a person's gait change. The proposed method
can help quantify the progress of physical therapy. Microsoft Kinect, a popular
platform for video games, was used to generate 25 joints to form a human
skeleton, and then the proposed method converted the coordinates of selected
Kinect joints into gait parameters such as spine tilt, hip tilt, and shoulder
tilt, which were tracked over time. Sample entropy measure was then applied to
quantify the variability of each gait parameter. Male and female subjects
walked a three-meter path multiple times in initial experiments, and their
walking patterns were recorded via the proposed Kinect device through the
frontal plane. Time series of the gait parameters were generated for subjects
with and without knee braces. Sample entropy was used to transform these time
series into numerical values for comparison of these two conditions.
