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The APASgait permits rotation and translation of any 3D figure through
the browser. This task can be perfomred from any place in the World !!!
In order to perform the Gait Analysis utilizing the APASgait, you
need the following instruments, measurements, and setups:
The APAS system consists of high speed cameras, computer, software, and
a calibration frame. These are all described in detail at the following website link here.
You must set up the subject with specific reflective markers at specific
locations.
There are 20 measurements that must be taken from the body
including nine measurements for each side of the body and an additional two for the body's
weight and the distance between the anterior superior iliac spines (ASIS). These
measurements are used for estimations in regression equations which allow estimations of
other parameters and obviously effect measurement error. This is one reason that the
APASgait should be used since the APASgait relies on video of the "real subject"
input into the system of calculations.
In 1990, Kadaba, Ramakrishnan, and Wootten at the Helen Hayes
Hospital proposed a marker system that used wands projecting about 7 to 10 cm from the
thighs and the calves. This marker set was proposed since the existing non-video
systems could not detect the markers. The APASgait elimates this kind of problem
since the video picture can always be utilized for marker placement validation. The
Helen Hayes marker set can be used with a higher level of accuracy since the video raw
data can be seen. The following figure illustrates the Helen Hayes marker set:
The more accurately the investigator can estimate these
locations,the better the resulting prediction. One of the APASgait major strength is
that the principle of analysis relies on video capture which is the real raw data.
Any system which relies on marker tracings is associated, by the nature of its basic
assumptions, with a large error. With the APASgait, you can always compare the
kinematics results to the video raw data by superimposing the calculated segment positions
and various segment rotations on the original video and check if it is valid.
Another advantage of the APASgait system is that there are no
requirements to set a special environmental conditions. The following video files present
examples of a worst case scenario with backup lights and white background.
![rudi_2401.AVI (472576 bytes)]() ![Rudi_2.AVI (444928 bytes)]()
Even under these adverse conditions, the APASgait was able to perform a
perfect gait analysis. In addition, you do not need the 6 cameras as is necessary
with the Vicon System, Motion Analysis Inc, System, or Peak. Three cameras
were sufficient for marker detection. With APASgait, if a marker is detected by only
one camera, the APASgait system pauses and requests the operator to manually digitize the
marker. Since the video is the input medium, not the markers, it is very easy to
digitize the missing point and continue the automatic process. Of course, with 5
cameras a missing point occasion rarely occurs. Consideration of price presents some
interesting choices: 5 high speed cameras from Vicon or Motion Analysis, or Peak may cost
in excess of $100,000. The APASgait with the cameras, computer, software and
all the other required components is priced at about $15,000 which compares favorable with
the $300,000 for Vicon and the others. In addition, the APASgait will be much more
accurate since markers tracking and then joint location prediction is associated with much
larger measurement errors then the APASgait video base system..
Check this Video file (1MB) To see some of
the APASgait capabilities
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