Automation Lecture 8

8/13/2019 Automation Lecture 8

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Automation Lecture 8.


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Process Automation

Factory Automation


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Limit Switches


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Inductive Proximity sensor

Inductive proximity switches are designed for wear-freeand non-contact detection of metal objects. For this they

use a high-frequency electro-magnetic AC field that

interacts with the target.


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Magnetic Field Sensors

Magnetic field sensors are actuated by magnetic fields and are

especially suited for piston position detection in pneumatic

cylinders. Based on the fact that magnetic fields can permeate

non-magnetizable metals, it is possible to detect a permanent

magnet attached to the piston through the aluminium wall of

the cylinder.


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Capacitive Proximity sensor

Capacitive proximity switches are designed for non-

contact and wear-free detection of metal (electrically

conductive) and non-metal (electrically non-

conductive) objects.


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Optical Proximity Sensor

Diffuse sensing mode

A diffuse sensor contains both emitter and receiver circuitry in asingle housing. In this sensing mode, an object is detected

directly in front of the sensor by detecting the sensors own

transmitted light beam reflected back from the objects surface.


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Optical Proximity sensor Light

Barrier


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Triangulation Sensor

Transmitter

L

Line CCD

Target

D

x

k


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3D Triangulation Sensor

Picture on ScreenObstacle

CCD Camera

Line Laser Source

a


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Rotary Encoder

Incremental


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Absolute Rotary Encoder


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http://pdb.turck.de/media/_en/Graphics/00087246_0.jpg


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Rotary Resolver


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Time of flight active ranging

Time of flight ranging make use of the propagation speed of an

emitted wave and measure the traveling time. The transmitted

wave can be sound, light or electromagnetic wave. If sound is

transmitted, the propagation speed is 342m/s, so the time of the

flight at a distance of 3m is about 20ms (to reach the target andget back) which is a measurable value. If the transmitted wave is

a laser beam, the propagation speed is 3 x 108m/s which is about

106times faster than it was in the case of sound transmitter. The

time of flight is 20ns! If the target is even closer than 3m it is a

very challenging task to measure so short times with small error.

On the other hand, if we need short scanning time and measuring

huge amount of points, the propagation speed of the sound does

not suit our requirements.


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Ultrasonic sensors

L

D


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Laser Rangefinder

Phase Measurement

L

Transmitter

D

Target


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Velocity and acceleration sensors

Doppler Radar


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Accelerometer

Automation Lecture 8

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