Biomedical Engineering Reference
In-Depth Information
3.3.2
Plantar Pressure Assessment
Plantar pressure assessment was performed with Footscan 1 m - 3D Gait Scientific
System - RsScan
®
International - Belgium. The plate consists of two units of
0.5 m
0.5 m installed in carbon mat and synchronized with each other. Each unit
has dimensions: length 578 mm
width 418 mm
height 12 mm, and 4096 sensors
(5.08 mm
7.62 mm).Thus, it is possible to operate as a unit of 1 m to gait analyses,
or only using one unit of 0.5 m to balance evaluation. The 1 m plantar pressure plate
use resistive technology using 8192 sensors (5.08 mm by 7.62 mm). The dimensions
are, 1068 mm, length by 418 mm width and 12 mm height. The actual study used
the left unit.
The plate was connected to analog-digital unit - Footscan
®
Interface 3D Box to
synchronize the entire system and convert the signal in digital values to pressure
data. The software provided by the manufacturer (Footscan 7.7 Balance 2nd
Generation) was installed in one computer system to collect and store pressure
data. The 100 Hz sample frequency was used to collect data from upright standing
position (10 s) and 250 Hz sample frequency for the stance phase of gait (4 s).
3.4
Protocol
In order to test the whole experimental procedure previously projected, as well
as verify its feasibility, before the real study two pilot studies were developed.
These studies, allowed determining the adequate space, the necessary equipment
and its assembly, the procedures to plate calibration. Also allowed to test the
protocols and establish routines for collecting and recording data. Simultaneously
with this process, we carried out a detailed study of the software (Footscan 7.7
Balance2nd Generation), to check if the proposed variables for study were possible
to achieve with his instrument. The plate was placed on the ground at a distance of
1.5 m from front wall and calibrated by manufacturer's specifications. Each upright
standing position test data was collect for 10 s. Each subject performed three trials.
The subjects stood on plate, barefoot, in her/his free selection usual natural position
more stable self considered. They were instructed to stay as quiet as possible during
the trial. To avoid disturbing effects due to eye movements over postural control,
the subjects were required, during the trial, to stare at a target. This target consisted
in a blue circle (diameter
0.16 m) drawn on a white sheet, positioned in the front
wall at 1.6 m of the ground. During the trials, an assistance stay close to subjects to
prevent instability and fall risk. Trial, in which the feet were not contacted with the
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