Date of publication 03.12.2018. [614043]

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Date of publication 03.12.2018.
0e605ec5 -9a05 -4b7d -8c61 -91f1183dd670
(December 2018 )
1Technical University of Cluj -Napoca , Cluj-Napoca , Romania
This work was supported by Embedded Department, Technical University of Cluj -Napoca.
ABSTRACT Medicine has always been one of the main areas of any civilization, suffering a continuing
development over ti me in order to have the best diagnostic and treatment methods by using the best
technologies.
The main objectives of this project were to integrate two topical concepts, technology and medicine, into a
system that is easy to use. This has created a device able to acquire foot data and process it so that it can be
interpreted as accurately and efficiently as possible. A real -time chassis and special data acquisition
modules provided by National Instruments were used to build the device. Data is measured by FSR sensors
with variable resistance, and finally software implementation is performed in the Labview programming
environment. .
INDEX TERMS Divider, FSR, foot, force, Labview, medicine, National Instruments, sensor.
I. INTRODUCTION
The relationship between human posture and dental
occlusion is the thematic and practical aptitude of many
studies undertaken and can be highlighted in a wider
context, aiming at establishing, on the basis of conclusive
results, a link between interconditioning. Viewed from the
practitioner's perspective, the analysis of these two factions,
both disparate and complicated, is a sine qua non for the
success of the therapeutic act.
The purpose of this study is precisely to provide both a
theoretical reference for the above -mentioned concepts and
to highlight and materialize, having practical and
experimental support, the importance of balancing this
relationship between occlusion and posture. The imperative
of separate and correlated assessment of these two concepts
lies in their prim ordial role in designing a viable therapeutic
strategy in the conscious and controlled management of the
treatment plan, which is reflected both in the quality of the
results obtained through the establishment of effective
therapeutic plans. The importance of understanding the
goals and correcting this interrelation, in a clinical context,
echoes both in diagnosis and in subsequent correct
assessment and management. By extrapolating the clinical
significance of the relationship between dental occlusion
and posture, it can be argued that understanding this
concept can be a prophylactic tool in the context of
preventing the installation of dysfunctional ADM syndrome
(Dento -Maxilar Apparatus), known in the literature as SADAM (Syndrome Algo Dysfonctionnel de l' Appareil
Manducateur).
II. CASE STUDY AND IMPLEMENTATION
At the conceptual level, the relationship between human
posture and dental occlusion is the thematic and practical
aptitude of many studies undertaken and can be highlighted
in a wider context, aimi ng at establishing, on the basis of
conclusive results, a link between interconditioning. Viewed
from the practitioner's perspective, the analysis of these two
factions, both disparate and complicated, is a sine qua non
condition for the success of the the rapeutic act.
For a clearer understanding of the concepts outlined
above, it is useful to briefly review the terminology to be
used, both for the definition of concepts and for an integrated
approach.
Human posture is defined as a body position and
involve s the musculature as an antigravitative function in
order to maintain a static and dynamic balance between the
anatomical segments involved in the objection of this
position [1].
The purpose of this study is precisely to provide both a
theoretical referenc e for the above -mentioned concepts and
to highlight and materialize, having practical and
experimental support, the importance of balancing this
relationship between occlusion and posture.
Plantar pressure is the distribution of the pressing forces
on the plantar surface. Measurement of planting pressure
provides indications of foot and ankle functions in
orthostatism, walking and other physiological activities.

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Measurement of planting pressures has become an important
tool in analyzing the relationship bet ween posture and dental
occlusion.
This study wants to evaluate whether the pressure
platforms are capable of detecting possible changes in
posture induced by dental occlusion changes.
For static measurements, the subjects sit with both feet
on the pressur e plate in an equilibrium position. Foot sole
was divided into 10 significant areas.

Figure 1 The top 10 areas of each leg

The meaning of the 10 zones of each foot exemplified in
the figure are:
HL – Exterior Calcai – en. Lateral Heel M3 –
Metatarsia n 3 – en. Metatarsal 3
HM – Interior Calcai – en. Medial Heel M4 –
Metatarsian 4 – en. Metatarsal 4
MF – Mijlocul piciorului – en.Midfoot M5 –
Metatarsian 5 – en. Metatarsal 5
M1 – Metatarsian 1 – en. Metatarsal 1 T2-5
– Degete 2 -5 – en. Toes 2 -5
M2 – Metatarsian 2 – en. Metatarsal 2 T1 –
Deget 1 – en. Toe 1
Legs are certainly the most desirable part of the body.
Walking, running or maintaining balance with one or both
feet on the support surface are common everyday activities.
Legs are often affected b y problems, which can be the source
of various wounds and pains throughout the body.
An important aspect is the center of gravity that should
follow the axis of the foot. The axis of the foot is defined as
the line joining the center of the heel with the c enter of the
second metatarsal. In dynamic measurements, deviation from
this axis can be explained by changing the center of gravity
due to a different rotation of the ankle.
The main objectives of this project are to build a
platform that meets the requir ements presented and to
provide the user with the satisfaction of integrating all
requirements and which, following the experimental results
obtained, will present a methodology for analyzing the
posture of a subject with visible differences in static pres sure
distribution.

The present paper aims at creating an experimental
system using sensors that allow the measurement of planting
pressure at five predetermined points. It is aimed both at
realizing a model and measurements made by the
experimental devic e in a static position. In the block diagram below, Figure 2, you can see the
main functional blocks and the interconnections between
them. Sensor data acquisition is carried out by CompactRIO
through its modules, and through the Ethernet port the
computer connection is made, where the user can see the
information they have acquired and of course they can
process them to follow what they are interested in. In the
continuation of the work, each subsystem will be detailed.

Figure 2 The block diagram of th e podometer

The cRIO -9068 controller is a chassis created by
National Instruments that covers a wide range of areas where
it can be used to adapt the chassis to the desired applications
by connecting the corresponding modules to the available
slots as the central element of the entire system.
NI 9219 module is a module compatible with Universal
Series C CompactDAQ and CompactRIO. With this, several
types of signal measurements can be made from sensors such
as tensiometers, RTD, thermocouples, load cells, r esistors
and other sensors. Channels are individually selectable, so
different measurements can be made with each of them. The
measuring ranges vary according to the type of measurement
with the possibility of measuring the voltage up to ± 60V and
± 25mA f or the current.

Figure 3 Method of measuring 2 -wire resistance [8]

The power source varies depending on the load
resistance between the HI and LO terminals. NI 9219
measures the voltage and then calculates the resistance. This
type of measurement doe s not compensate for the strength of
the wires.
FSR Pressure Force Measurement Sensors
In general, the basic construction of the FSR consists of
two membranes separated by a thin air space. The air gap is
maintained by a spacer around the edges and the st iffness of
the two membranes. One of the membranes has two sets of
interdigitated branches that are electrically distinct, each set
connecting to a single trace on the tail. The other membrane

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is covered with FSR ink. When pressed, the FSR ink shortens
the two traces together with a strength that depends on the
applied force. At low forces, only the highest branches
protrude into contact. With larger forces, more and more
points are in contact. The result is that the resistance between
the fingers is invers ely proportional to the applied force.

Figur e 4 Basic Construction of FSR [9]

FSR 402 (Force Sensitive Resistor) detects physical
pressure, pressure and weight. The output resistance is
inversely proportional to the pushing force, in the sense that,
with the increase of the pushing force, its resistance
decreases; in other words FSR is nothing bu t variable
resistance. In the absence of any stress applied to the sensor,
the output resistance is greater than 1MΩ.

Figure 5 Output FSR feature [10]

Figure 5 shows the typical resistance curve with respect
to strength, having logarithmic data. This pa rticular force –
strength curve is obtained from the FSR402 sensor catalog
sheet having an active circular surface 12.7 mm in diameter.
"Drive force" or threshold threshold is usually defined
as the force required to bring the open circuit sensor to a
resist ance less than 100kΩ. This force is influenced by the
thickness and flexibility of the substrate and surface, the size
and shape of the actuator and the thickness of the adhesive
(the size of the inner space between the membranes).
Immediately after turnin g on, the resistance decreases very quickly. With light and then intermediate forces, the
sensitivity of the sensor is very high. Going to the upper end
of the force range, the sensitivity of the sensor becomes
smaller, the response becomes finally saturat ed up to a point
where the increases in force lead to little or no decrease in
resistance. Saturation can be pushed forward by spreading
the force applied to a larger actuator.
Sensor measurement techniques are divided into three:
– voltage divider
– conve rting the current into a voltage
– direct reading of the sensor.

Methods and techniques for measuring FSR

A. Voltage Divider

Figur e 6 Voltage Divider with FSR [9]

For a simple force conversion, the FSR can be
integrated into a voltage divider.
In this co nfiguration, the output voltage increases as
the applied force increases. Circuit inversion of RM resistor
with RFSR leads to output voltage that will be inversely
proportional to force, output voltage will decrease as the
force increases.
The choice of RM resistance is based on the desire
to maximize the range of sensitivity and current limitation.
This depends on the measurement impedance of the circuit,
the voltage divider can still be connected to an amplifier.
A set of signals related to output force a nd voltage are
illustrated in the diagram above for different RM resistance
values and a supply voltage of the divider V + = + 5V.

B. Measuring FSR with Voltage Conversion – Variant
1

Figur e 7 Conversia curentului FSR în tensiune [9]

In this circuit, the FSR component passes the input
current into the current -to-voltage converter.
By using a positive reference voltage, the output of
the operational amplifier will be between 0V and -VREF, so
dual power is required. With a negative reference voltage, the

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output will be positive and range from 0V to + VREF.
Therefore, we can deduce that the VOUT voltage is
inversely proportional to RFSR. The change of RG and / or
VREF changes the slope of the response. The following is an
example of the sequence used for choos ing component
values and output variation:
For a variable control device from one man to
another, as a joystick, the maximum applied FSR is about 1
kg. Testing an FSR example shows that RFSR corresponding
to 1 kg is approximately 2.9 kΩ. If the VREF is – 5V and an
output swing from 0V to + 5V is desirable, then RG should
be roughly equal to this minimum RFSR. A full balancing
from 0V to + 5V is thus achieved. A set of curves described
by the relationship between force and VOUT is shown in the
Figure for a standard FSR using this interface with a variety
of RG values.
The current through the FSR device must be limited to
an applied force of less than 1 mA / cm2. As in the voltage
dividing circuit, adding a resistor in parallel to the RFSR will
give a define d resting voltage, which is essentially a zero
force intercept value. This can be useful when resolving to
low forces is desired.

C. Measuring FSR with Voltage Conversion – Variant
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These circuits are a slightly modified version of the
current -voltage conve rter detailed above.

Figure 8 Current conversion circuit in voltage [9]

The output of the above circuit is described by VOUT
and has a range of VREF / 2 to 0V range. If RG is higher
than RFSR, the output is in negative saturation.

Figure 9 Current con version circuit in voltage [9]

The output range of this circuit is from VREF / 2 to
VREF. If RG is higher than RFSR, the output will go into
positive saturation.
For any of these configurations, a zener diode placed in
parallel with the RG will limit the voltage built on the RG. These models give half of the output range of the previous
circuit but require only one part of the power supply and
positive reference voltages. As in the previous circuit, the
FSR current should be limited to less than 1 mA / cm2
applied force.
To implement these circuits, as a suggestion, we can use
the LM358 and LM324 operational amplifiers, but depending
on the application, you can choose any other amplifier
model.
Advantages:
– Easy to use and implemented in various applicatio ns, often
used in musical instruments
– Relatively low cost
Disadvantages:
– The most important disadvantage is given by the central
component, the spongy material, which takes a while to
return to the original form, which can lead to measurement
errors
– The inside material is very sensitive to being pressed: the
pressure response is nonlinear and varies with time,
temperature and humidity

Implementation of the adopted solution

For the practical testing of the system, a prototype was
built to test the op eration of the analog data acquisition
modules whose properties they recommended for this
project. These analog modules will collect the information
provided by the integrated sensors in the platform on which
the person under study is placed to analyze the posture
difference.

Figure 10 Device with polycarbon support and location of sensors on it

The FSR402 sensors are nothing but variable resistors,
they can be used by any of the methods detailed in the
theoretical grounding. Normally, they are passive sensors,
and in order to measure them, they need to be integrated into
an excitement configuration so that the output is readable, but
because the NI 9219 modules are designed to provide the

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possibility to measure different signals, including resistance
measurement, we will not use additional circuits for sensing
excitement and reading, although such implementation is
possible. NI 9219 modules, through software configuration,
can measure resistance by directly connecting the sensors to
the modules. It has t he ability to excite the sensor with a
current up to 25 mA, read a voltage, and finally convert to
ohms.

Figure 11 Sensor output feature and Excel created

The implementation of the adopted solution involves
two major stages: the hardware development a nd then the
software of the device. Hardware development has taken into
account important features of data acquisition, as well as
creating a device that can support multiple measurements
without damaging it in a functional and visible way.
From the practi cal implementation of the entire system
are two important ways of how to acquire and process the
data, so first used a cheap implementation and testing variant
that involved development around the Arduino development
board, and then attention was aimed at developing the device
along with the chassis and modules provided by National
Instruments.

Figure 12 Experimental test and measurement circuit

Labview based software development includes the
processing and interfacing of analog data measured by
hardwar e. Software development has reached an interface
environment that provides important insights into the
difference in posture of the subject. Another important
feature is the possibility of saving data, a utility that helps in
the timing of the data acquire d.

Figure 13 Main VI Achizitie_Date

Figure 14 Front Panel Graphics Interface

The functionality of the interface is simple and easy to
understand, provides important information about each point
of interest of the feet where the sensors are locate d.
The "Want to Save?" Button has a useful functionality

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in view of the fact that the user may not want to save the
measurements to be performed, but only to see what happens
in real -time on all medical points of interest.
Each of the five graphs shows two signals for the two
sensors located in the same position but on different legs.
This way you can compare the two feet points in real time
with no other data processing.

REFERENCES
[1] Baldini A, Nota A, Tripodi D, Longoni S, Cozza P. Evaluation
of the correlation between dental occlusion and posture using a
force platform. Clinics. 2013;68(1):45 -49.
[2] Bricot B: La reprogramation postural globale. Ed Sauramps
medical Montpellier 1996.
[3] Bricot B : Cours du CIES. Paris janv 2006.
[4] Clauzade M., Marty JP: Orthoposturodontie vol 2 ed SEOO.
2006.
[5] Sakaguchi K, Mehta NR, Abdallah EF, Forgione AG,
Hirayama H, Kawasaki T, et al. Examination of the relationship
between mandibular position and body posture. Cranio.
2007;25(4):237 -49
[6] National Instruments website, http://www.ni.com/white –
paper/11564/en.
[7] http://www.carl -engler –
schule.de/culm/culm/culm2/th_messtechnik/labview/lvstart/
374473d.pdf.
[8] http://www.ni.com/pdf/manuals/374473a_02.pdf.
[9] FSR400 -Series -Integration -Guide.pdf .
[10]
https://www.sparkfun.com/datasheets/Sensors/Pressure/fsrguide.p
df.
[11] http://www.robotpark.com/academy/capacitive -pressure –
sensor -21025