Industrial Electronics: College of Engineering and Architecture - Electronics Engineering Department
Industrial Electronics: College of Engineering and Architecture - Electronics Engineering Department
Industrial Electronics: College of Engineering and Architecture - Electronics Engineering Department
Experiment No. 7
STRAIN GAUGE AND ULTRASONIC TRANSDUCERS
Course: EE340 Section: EE31S2
Group No.: 2 Date Performed: 09/15/2022
Group Members: Date Submitted: 09/17/2022
Bumatay, Charles Patrick Instructor: Ms. Marjorie Villanueva
Bunga, Dexter
Cruz, Vince Allen
Hamtig, Richard Ahmir
Santos, Timothy Brian
Villanueva, Darwin
1. Objective(s):
To present the basic concepts of force measurement through a strain gauge and
introduce the characteristics of ultrasonic transducers.
3. Discussion:
A strain gauge is a metal grid in the shape of a Greek fret that is created by
photoengraving on an insulating support. At the ends of such fret there are the terminals
for the connection to the measurement circuit. The main characteristic of a strain gauge
is that of varying its electrical resistance with the variation of the deformation to which it
is subjected.
4. Equipment:
De Lorenzo 3155E25
Connecting Wires
Digital Multimeter
5. Procedure:
Activity 1 – Measurement of deformation through a Strain Gauge
General Guideline
Always turn on the base frame first before turning on the DL Student Navigator 2
Software. Turn off the software after performing one activity and turn it on before
performing a new activity to reset the software and hardware communication.
Schematic Diagram
Figure 6.1
Instrumentation Amplifier
The circuit that will be used is the one in figure 6.2 that represents the function
that is performed by the STRAIN GAUGE block. The sensor has the capability of
varying its resistance as a function of the deformation to which it is subjected. However,
these variations are very weak and, therefore, it is necessary to use an amplifier to be
able to measure them.
Figure 6.2
1. Connect, through two leads, the terminal that is connected to R4 to the terminal
of the inverting input and the terminal that is connected to R1 to the terminal of
the non inverting input of the INSTRUMENTATION AMPLIFIER.
2. Take, through the dip switches, the gain of the INSTRUMENTATION AMPLIFIER
to the value G=1000 (1, 2, 3 to OFF, while the 4th dip switch must be set to ON).
3. Insert the multimeter, set for the measurement of direct voltages, between the
terminal Vo of the INSTRUMENTATION AMPLIFIER block and the earth and
measure the voltage.
4. Make sure that the screw does not touch the sheet on which the strain gauge is
mounted.
5. Reset the output voltage of the amplifier by operating on R0.
6. Move the screw until it touches the aluminum sheet. At this point rotate the screw
by half turn.
7. Write the measurement that you read on the multimeter in Table 6.1.
8. Repeat such measurement for all the positions that are listed in the table.
9. Comment the behavior of the measured voltage as a function of the position of
the screw.\
Table 6.1
In measuring theory this is the mathematical model of the transducer. The most
convenient situation is the linear correlation between distance and output voltage.
D = aV + b
1. For distance measurement make a setup like figure 6.3 and fix a measuring tape
in line with the transducer.
Figure 6.3
2. Next, find a target (a wood parallelepiped) which will travel along measuring tape
for experimenting with ultrasonic transducer.
3. Pay attention that the target must be all the time in front of ultrasonic devices in
order to respect the principle of ultrasonic measurement, as figured with dashed
curves. For getting familiar with this experiment, the target must be kept
perpendicular over the measuring tape line.
4. With all these preparations, start distances measuring with this transducer. For
voltage measurements, a simple voltmeter could be used.
5. Measuring distance is not fast variating event. Moving the target and, in the same
time reading the voltage value on the voltmeter, are easy tasks. Put the values in
Table 6.2.
Table 6.2
Nr. of Voltag Distan Obs.
measureme e ce
nts
1 u1 D1
2 u2 D2
3 u3 D3
4 u4 D4
6. Move the target along the measuring tape. All the time, keep your eye on the
voltmeter. Each established position of the target must be associated with a
College of Engineering and Architecture – Electronics Engineering Department 4
INDUSTRIAL ELECTRONICS
Table 6.3
Nr. of 20 22 24 26 28 30 32 34 36 Obs.
measurem cm cm cm cm cm cm cm cm cm
ents
40 kHz U1 U2 U3
32 kHz
36 kHz
38 kHz
42 kHz
44 kHz
46 kHz
11. Normally, for accurate measurements you must place the target in perpendicular
position against the ultrasonic sensor axe. With this part of the experiment you
may want to see how much variation we could have from the perpendicular
position of the target.
12. Adjust the frequency of the generator at 44 kHz. Place the target at 20 cm. This
will be the start point in all next operations.
Figure 6.4
13. Rotate the target with one hexadecimal grade step. Record the voltage values,
for each position of the target. Stop when the variation of the voltage is
significant. Make your observations related to the target transversal position.
6. Observation:
In activity 1,we noticed that the voltage increases as the screw's position does. In
activity 2, the sensor wasn't functioning, therefore there was no data to gather.
7. Interpretation:
8. Conclusion:
We therefore conclude that a strain gauge is a particular class of electrical sensor used
to monitor and control strain. They are occasionally used as parts of other sensors,
such as pressure transducers and load cells. A strain gauge's resistance alters when
forces are applied, producing a range of electric outputs.
1. Explain the theory of proximity sensing. What are the common applications of
proximity sensors in industrial settings?
- The presence of an object is detected by a proximity sensor, a form of non-
contact sensing device, when it enters its field of vision. Depending on the
kind of proximity sensor, it may be able to find a target via electromagnetic
fields, sound, light, or infrared (IR) radiation.
2. How does an ultrasonic transducer measure distance? State the factors that
affects its accuracy of measurement.
- Ultrasonic sensors work by releasing sound waves at frequencies that are
higher than those heard by people. The transducer of the sensor serves as a
microphone to record and send ultrasonic sound. Our ultrasonic sensors, like
many others, use a single transducer to send and receive pulses. By
monitoring the interval between delivering and receiving the ultrasonic pulse,
the sensor calculates the distance to a target.
3. Design a simple proximity sensor circuit that can be used in conveyor systems
and automation.