Notesale: Turn your study into money

Document Preview

Extracts from the notes are below, to see the PDF you'll receive please use the links above

---

Mechatronics

Sensors & Transducers in Mechatronics Systems

Sensors & Transducers in Mechatronics
Systems


...



Transducers
Transducers are the basic elements that converts or transforms one form of

energy to another form
...
Transducers are mainly used to quantify the physical, electrical, fluidic &
mechanical parameters such as temperature, pressure, magnetic field, voltage, flow,
vibration & so on
...

For

the

observation,

quantification,

measurement

&

manipulation

of

measurands, different types of transducers with different transduction principles are
used
...


 Sensors
A sensor consists of transducer whose function is to convert the one form of
energy into electrical form of energy
...

Example:
Temperature Sensor – Thermocouple
Input – Temperature
Output – E
...
F (Electrical Parameter)
...
Transducer is an
essential element of a sensor
...


Mr
...
P
...

Example : Photo electric transducers, Thermocouple, etc
...

Example : strain gauge, photo cell (LDR), etc
...

Examples : thermistor, thermocouple, etc
...

Example : LVDT, etc
...

Example : Strain gauge, thermistor, etc
...

Example : turbine meter, etc
...
Chavan R
...
, Fabtech Technical Campus

Page 2

Mechatronics

Sensors & Transducers in Mechatronics Systems

 Photoelectric sensor
A photoelectric sensor, or photo eye, is a device used to detect the distance,
absence, or presence of an object by using a light transmitter
...
In this mode, an
object is detected when the light beam is blocked from getting to the receiver from the
transmitter
...
An object is sensed when the beam is interrupted and fails to reach the
receiver
...
In this mode, an
object is detected when the receiver sees the transmitted source rather than when it
fails to see it
...
Chavan R
...
, Fabtech Technical Campus

Page 3

Mechatronics

Sensors & Transducers in Mechatronics Systems

 Hall Effect Sensors
Principle:
When a current carrying semiconductor plate is placed in a transverse magnetic
field, it experiences a force (Lorentz force)
...
This is known as Hall Effect
...
The side towards which the
moving electron deflected becomes negatively charged and the other side of the plate
becomes positively charged or the electrons moving away from it
...
The result is a traverse potential difference known as
Hall voltage
...
These output faces are at same
potential when there is no transverse magnetic field passing through the element and
voltage known as Hall voltage appears when a transverse magnetic field is passing
through the element
...

The direction of deflection depends on the direction of applied current and the direction
of magnetic field
...
Chavan R
...
, Fabtech Technical Campus

Page 4

Mechatronics

Sensors & Transducers in Mechatronics Systems

 Optical Encoders
It is used to measure position, velocity, acceleration and direction of movement
of rotors
...

Construction & Working:

Absolute Encoders
Principle:
The principle of operation is that they provide a unique output corresponds to
each rotational position of the shaft
...
Chavan R
...
, Fabtech Technical Campus

Page 5

Mechatronics

Sensors & Transducers in Mechatronics Systems

The output is in the form of binary num bers representing the angular position
...
The slots are arranged in such way that they give a binary number
...
This pattern is called as track
...
The number of the track determines the resolution of the encoder
...


Mr
...
P
...
If there is a metal near to this alternating
Mr
...
P
...
The EMF cause current to flow
...


Construction & Working
It has two identical coils
...
Eddy current start to flow due to AC(conducting
object) close to sensor
...
Due to this opposition reduction flux is created
...
The sensor consists of an induction loop
...
The
inductance of the loop changes according to the material inside it and since metals are
much more effective inductors than other materials the presence of metal increases the
current flowing through the loop
...


 Linear Variable Differential Transformer (LVDT)
It consists of three symmetrically spaced coils
...
Secondary coils are connected in series opposition and
equally positioned with respect to primary coil
...
Chavan R
...
, Fabtech Technical Campus

Page 8

Mechatronics

Sensors & Transducers in Mechatronics Systems

Mr
...
P
...
Chavan R
...
, Fabtech Technical Campus

Page 10

Mechatronics

Sensors & Transducers in Mechatronics Systems

 Capacitive Sensors
It is used for measuring, displacement, velocity, force etc
...

Formula :

By Changing the Distance between Two Plates:
Mr
...
P
...
The capacitance is directly
proportional to the area of the plates and varies linearly with changes in the
displacement between the plates

By Varying the Dielectric Constant:
The change in capacitance can be measured due to change in dielectric constant
as a result of displacement
...


Mr
...
P
...
Chavan R
...
, Fabtech Technical Campus

Page 13

Mechatronics

Sensors & Transducers in Mechatronics Systems

 Strain gauge accelerometer

Mr
...
P
...
Chavan R
...
, Fabtech Technical Campus

Page 15

Mechatronics

Sensors & Transducers in Mechatronics Systems

 Torque measurement using torsion bar

Mr
...
P
...
Chavan R
...
, Fabtech Technical Campus

Page 17

Mechatronics

Sensors & Transducers in Mechatronics Systems

 DC tacho generators

Mr
...
P
...
Chavan R
...
, Fabtech Technical Campus

Page 19

Mechatronics

Sensors & Transducers in Mechatronics Systems

Mr
...
P
...
In
presence of an electric field, when such a crystal material heats up, its electrical
dipoles line up as shown in figure
...
On cooling, the
material retains its polarization
...
This
phenomenon is the measure of detection of movement of an object
...
4
...
Initially the
electrodes are in electrical equilibrium with the polarized material
...
This leads to charge
imbalance at the interface of crystal and electrodes
...


Mr
...
P
...
Chavan R
...
, Fabtech Technical Campus

Page 22



---