Mechatronics Engineering Lecture 5: Sensors & Transducers
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Questions and Answers

What does LVDT stand for?

Linear Variable Differential Transformer

What is the primary purpose of an LVDT?

To measure linear displacement

LVDTs are passive transducers.

False

What are the main components of an LVDT?

<p>A single primary coil and two secondary coils</p> Signup and view all the answers

What is the output signal of an LVDT?

<p>AC voltage</p> Signup and view all the answers

Which of the following is NOT an advantage of LVDTs?

<p>Large displacement for small output</p> Signup and view all the answers

LVDTs are susceptible to stray magnetic fields.

<p>True</p> Signup and view all the answers

What is the principle behind a capacitive sensor?

<p>The principle of variable capacitances</p> Signup and view all the answers

What type of transducer requires external power for operation?

<p>Capacitive transducer</p> Signup and view all the answers

Capacitive sensors are sensitive to changes in temperature.

<p>True</p> Signup and view all the answers

Which of the following is NOT a common use of capacitive transducers?

<p>Measuring temperature</p> Signup and view all the answers

What is the basic principle of a piezoelectric sensor?

<p>They generate an electric voltage when subjected to mechanical force or stress.</p> Signup and view all the answers

Which of these is the most well-known material used in piezoelectric sensors?

<p>Quartz</p> Signup and view all the answers

What is a common application of piezoelectric sensors?

<p>Measuring pressure</p> Signup and view all the answers

Piezoelectric sensors are primarily used for static pressure measurements.

<p>False</p> Signup and view all the answers

What is the purpose of a photoelectric sensor?

<p>To detect the presence, absence, or distance of an object.</p> Signup and view all the answers

Which of these is NOT a mode of operation for photoelectric sensors?

<p>Inductive</p> Signup and view all the answers

Photoelectric sensors only require a power source for operation.

<p>True</p> Signup and view all the answers

What is a light sensor?

<p>It is a passive device that converts light energy into an electrical signal.</p> Signup and view all the answers

Light sensors can only detect visible light.

<p>False</p> Signup and view all the answers

What is a common type of light sensor?

<p>All of the above</p> Signup and view all the answers

In the context of light sensors, what does LDR stand for?

<p>Light Dependent Resistor</p> Signup and view all the answers

Photoresistors require a long response time to changes in light intensity.

<p>True</p> Signup and view all the answers

What is the basic principle of an infrared sensor?

<p>It uses an IR LED to emit infrared light and a photodiode to detect it.</p> Signup and view all the answers

Infrared sensors are limited to direct incidence only.

<p>False</p> Signup and view all the answers

What is the function of an encoder?

<p>To measure the movement of a mechanical part.</p> Signup and view all the answers

What are the two main categories of encoders?

<p>Rotary and Linear</p> Signup and view all the answers

Absolute encoders can determine the position of the shaft even after power cycling.

<p>True</p> Signup and view all the answers

What is the primary difference between absolute and incremental encoders?

<p>Absolute encoders output a unique code for each position, while incremental encoders output pulses for each increment of movement.</p> Signup and view all the answers

Study Notes

Mechatronics Engineering (OFRME200) Lecture 5

  • Course: Mechatronics Engineering (OFRME200)
  • Lecture: 5
  • Level: 2
  • Semester: Fall
  • Instructor: Walaa Shoeib
  • University: Menoufia University, Faculty of Electronic Engineering

Chapter 2: Sensors & Transducers

  • Topic: Sensors and Transducers
  • Subtitle: Chapter 2
  • Note: Electronic Measurements

Linear Variable Differential Transformer (LVDT)

  • Device: Linear Variable Differential Transformer (LVDT) or Linear Variable Differential Transducer (LVDT)
  • Function: Measures linear displacement
  • Principle: Works on the principle of variable inductance
  • Components: Three coils wound sequentially around a hollow, non-magnetic tube. One primary coil and two secondary coils.
  • Operation: As the core moves, the magnetic flux linking the secondary coils changes. This produces an output voltage that is proportional to the displacement. The output voltage is the difference between the voltages of the two secondary coils.
  • Output: Proportional to the displacement
  • Advantages: Low friction loss, low power consumption, direct conversion to electrical signals, greater sensitivity
  • Disadvantages: Needs extra setup, delicate to stray magnetic fields, large displacement for little output, requires demodulator to convert AC signal to DC.
  • Applications: Measuring linear displacement, force and pressure, humidity in gases

Capacitive Sensor

  • Type: Capacitive displacement sensor
  • Function: Used for measuring displacement, pressure and other physical quantities
  • Principle: Works on the principle of variable capacitance. Capacitance between plates changes for various reasons; overlapping of the plates, distance between the plates and dielectric constant
  • Advantages: Very sensitive, requires small output power
  • Disadvantages: Metallic parts require insulation and cables connecting across the transducer cause error
  • Applications: Measuring linear and angular displacements, force, pressure, humidity in gases, volume, density, weight, etc
  • Capacitive transducer: Contains two parallel metal plates separated by a dielectric medium (air, material, gas or liquid). Changes in the distance between plates alter capacitance, which is measured.

Piezoelectric Sensor

  • Principle: Certain materials generate an electric voltage when mechanically deformed; e.g. quartz crystal.
  • Applications: Vibration monitoring, pressure sensing, force measurement, structural health monitoring
  • Advantages: Simple construction, inexpensive materials, Wide range of pressure and temperatures.
  • Disadvantages: Only for dynamic pressure measurement, low output voltage

Photoelectric Sensor (Photo Eye)

  • Function: Detects distance. presence, and absence of objects
  • Types:
    • Through-beam: An object in the beam path interrupts the light signal.
    • Retro-reflective: An object is reflected back in the beam to signal.
    • Proximity-sensing (diffused): Radiation must reflect off the object to reach the receiver.

Infrared (IR) Sensor

  • Function: Sensing radiation
  • Components: IR LED (emitter), IR photodiode (detector)
  • Principle: Changes in intensity of reflected IR light are converted into output voltage changes to measure objects
  • Uses: Measuring distances, detecting the presence of objects or their absence.

Encoder

  • Function: Measures movement of mechanical parts/ measuring rotation/position
  • Types:
    • Linear and Rotary.
  • Subtypes:
    • Absolute/ Incremental
    • Magnetic, Optical, Inductive, Laser and Capacitive

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Description

This quiz covers Lecture 5 of the Mechatronics Engineering course (OFRME200) focusing on Chapter 2, which explores Sensors and Transducers. Special emphasis is placed on the Linear Variable Differential Transformer (LVDT), its principles, components, and operation. Test your knowledge on these essential electronic measurements and concepts.

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