Interfacing Physics Sensors

1
Interfacing Physics Sensors Using National
Instruments Educational Laboratory Virtual
Instrumentation Suite LabVIEW by Eric Ethridge
Figure 2-1
Introduction The purpose of my project is to gain
a basic understanding of how to use LabVIEW in
conjunction with physics sensors connected to
ELVIS, and to create virtual instruments to work
with real-life physics labs. I am taking lab
manuals and creating virtual instruments (VIs)
for each of the labs while slowly taking away
certain objects so that students can learn how to
program using LabVIEW. The object is to allow
students to have enough experience with LabVIEW
so that if they were to encounter it elsewhere
they would already have a basic knowledge of how
to use LabVIEW.
Conclusions Learning how to program using LabVIEW
was very intuitive. Explaining how to program a
VI can make it sound very complicated but it is
fairly simple. My manual gives students very
concise instructions to quickly create VIs to
help with their labs.
Left to right motion detector, force sensor, gas
pressure sensor, temperature probe
National Instruments Educational Laboratory
Virtual Instrumentation Suite (NI ELVIS)
Figure 2-2
Results I was successfully able to create VIs
for every lab in the Mechanics and Thermodynamics
books of the RealTime Physics lab manual series.
These included VIs that incorporated the use of
two sensors working together. For example, one
lab required that you calculate the spring
constant of a spring, then use the spring
constant to calculate the mechanical energy. This
process can be seen in Figure 1. Figure 1-1 shows
the VI that calculates the initial distance from
the spring to the motion detector which is in
turn used to calculate the spring constant.
Figures 1-2 and 1-3 show the process of placing
weights onto the spring to collect force and
distance data which is then used along with the
initial distance to calculate the spring
constant. The spring constant is calculated using
the equation kF/x, F being the force exerted on
the spring and x being the distance between the
spring and motion detector. Figure 1-4 shows the
results of calculating the spring constant
graphically. The slope is the spring constant.
Figure 1-5 shows the final VI where the
mechanical energy is calculated and graphed.
Figure 1-6 is the code that makes up the final
VI. I also experimented with electrical
circuits. Figure 2-1 shows a parallel circuit
that is using two current probes to read the
current that is flowing through each bulb when
the switch is either open or closed. Figure 2-2
shows a circuit using a 10 ohm resistor is having
the current running through the resistor
monitored. Figure 2-3 shows a parallel circuit
with two different sections.
References Essick, John. Advanced LabVIEW
Labs. Laws, Priscilla W. David R. Sokoloff.
Ronald K. Thornton. RealTime Physics.
Materials Methods The materials I worked with,
as seen in the above pictures, consisted of the
National Instruments Educational Laboratory
Virtual Instrumentation Suite or NI ELVIS and
several sensors from Vernier Software
Technology. To explain how to use LabVIEW, first
I had to learn how to use it myself. I used John
Essicks book Advanced LabVIEW Labs to help get
myself acquainted with the LabVIEW graphical
programming language and using the Data
Acquisition (DAQ) Board. I was then able to begin
creating VIs of my own. I took VIs that were
created for the sensors and taking my knowledge
of LabVIEW, re-programmed them for a purpose that
suited a particular lab. For example, I took the
VI created for the motion detector and programmed
the VI to calculate and display the velocity of
an object on a graph.
Figure 2-3
Acknowledgments I would like to thank Dr. Julie
Talbot for letting me work on this project and
Dr. Bob Powell for providing the equipment. I
would also like to thank the National Science
Foundation STEP grant DUE-0336571 for funding
the work on my poster.
Further Information http//www.ni.com for
information on ELIVS and LabVIEW
Figure 1-2
Figure 1-3
Figure 1-1
Figure 1-4
Figure 1-5
Figure 1-6