Biomedical Engineering Reference
In-Depth Information
Fig. 3
Shoe design to
integrate the sensors for
in-plane plantar vector force
measurement [
30
]
in-place calibration. The calibration was achieved using an indirect methodology,
with the help of a force platform. Comparing the results from these two techniques,
one gets a procedure where the sensor is previously calibrated. Only after this step,
the system is ready for any kind of plantar force measurements. In the gait analyses
conducted, obtained results were in agreement with those published by Hosein et al.,
showing a peak value in the anterior-posterior component, happening about 22%- of
the gait cycle (e.g. 40% single contact phase) with a forward direction and another
at about 50%-55% of gait cycle in the backward direction [
21
].
Therefore, during normal gait, these results show that when the foot contacts
the ground, apart from the well-known plantar pressure profile, one can state that
anterior-posterior component first increases in the forward direction at about 60
ı
towards lateral direction (or left for the right foot), while decreasing during total
contact and increasing afterwards until reaching a peak in the posterior direction, at
about 240º.
One interesting application of the GRF information obtained with force platforms
is the work developed by Burnfield et al
.
With the vertical and in-plane (or shear)
components, these authors defined a coefficient CoF
u
- “utilized” Coefficient of
Friction - calculated as a ratio between the shear and vertical components, which is
used to determine a risk factor to classify the friction coefficient in order to define a
probability of falling by losing adherence [
5
]. This type of study can also be used in
the choice of materials for pavement design namely in public or exterior areas [
8
].
If the sensing elements or matrix are positioned inside the shoe, the knowledge
can be used to study the insole or shoe sole materials causing a better force
distribution and hence giving the sensation of best comfort. This approach will be
very interesting for shoe industry. At present, this aspect is overcome by introducing
orthoses in the shoe, which results in an effective way of reducing abnormal
pressures [
6
,
15
,
28
], although, as shown by Hennig et al., the design and the
fabrication process are the major factors responsible for the pressures observed in
the foot. Even though, only a medical study on the occurrence of injuries related to
the use of sportive shoes will enable a better understanding of the relevant factors
[
20
]. From an opposite side of view of comfort shoes, there are the high heel shoes,
