LECTURE#03 AUTOMATION BUILDING BLOCKS

builderanthologyΤεχνίτη Νοημοσύνη και Ρομποτική

19 Οκτ 2013 (πριν από 4 χρόνια και 23 μέρες)

105 εμφανίσεις

By: Engr. Irfan Ahmed Halepoto

Assistant Professor

LECTURE#03

AUTOMATION BUILDING BLOCKS

AUTOMATION & ROBOTICS

AUTOMATION


Use

of

control

systems

and

information

technologies

to

control

industrial

machinery

and

processes,



Reducing

the

need

for

human

involvement

in

the

production

of

goods

and

services
.



AUTOMATION BUILDING BLOCKS


Sensors


Analyzers


Actuators


Drives


Vision systems


(Machine/Computer
)


Sensors

Analyzers

Actuators

Drives

Vision systems

SENSORs


A

sensor

is

a

device

which

receives

and

responds

to

a

signal
.


Sensor

measures

a

physical

quantity

and

converts

it

into

a

signal

which

can

be

read

by

an

observer

or

by

an

instrument
.


Thermocouple

converts

temperature

to

an

output

voltage

which

can

be

read

by

a

voltmeter
.


Sensor Category wise……..


Temperature sensors


Light Sensors


Force Sensors


Pressure Sensors


Displacement Sensors


Motion Sensors


Sound Sensors

Sensors operation wise ……


Resistive


Inductive


Capacitive


Piezoelectric


Photoresistive


Elastic


Thermal

Building Blocks:
sensor Versality

Inductive proximity sensors

Linear encoder

Absolute rotary

encoder

Sensors variety

Building Blocks:
sensor devices

Building Blocks


Sensor features


Range
:

normal

range

(
maximum

&

minimum

values)

over

which

the

controlled

variable

might

vary?



Resolution

or

discrimination
:

smallest

discernible

change

in

the

measured

value


Response

time
:

Amount

of

time

required

for

a

sensor

to

completely

respond

to

a

change

in

its

input
.



Error
:

difference

between

the

measured

and

actual

values
.



random

errors

&

systematic

errors


Accuracy
:

How

close

the

sensor

comes

to

indicating

the

actual

value

of

the

measured

variable?



Building Blocks


sensor features


Precision
:

How

consistent

the

sensor

is

in

measuring

the

same

value

under

the

same

operating

conditions

over

a

period

of

time?


Sensitivity
:

How

small

a

change

in

the

controlled

variable

the

sensor

can

measure?



Linearity
:

Exaggerated

relationship

between

the

ideal

and

the

actual

measured

or

calibration

line



Dead

band
:

How

much

of

a

change

to

the

process

is

required

before

the

sensor

responds

to

the

change?



Costs
:

What

are

the

costs

involved

-

not

simply

the

purchase

cost,

but

also

the

installed/operating

costs?


ANALYZERS


A

device

that

analyzes

given

data
.


It

examines

in

detail

the

structure

of

the

given

data

and

tries

to

find

patterns

and

relationships

between

parts

of

the

data
.



Through

analyzers,

various

parameters

like

rotation,

speed,

position,

angles

etc

can

be

analyzed

in

a

specific

process

control
.


Analyzer

can

be

a

piece

of

hardware

or

a

software

program

running

on

a

computer
.


Process

Analyzer


Bar

Code

Analyzer


Logic

Analyzer


Spectrum

Analyzer


Encoders




Process A
nalyzers

Barcode Analyzers

Barcode Analyzers

Barcode Patterns

Building Blocks: Analyzers

Encoder

example
:

An

absolute

optical

encoder

has

8

rings,

8

LED

sensors,

and

8

bit

resolution
.

If

the

output

pattern

is

10010110
,

what

is

the

shaft’s

angular

position
?



Ring

Angle
(deg)

Pattern

Value
(deg)

1

180

1


180

2

90

0

3

45

0

4

22.5

1

22.5

5

11.25

0

6

5.625

1


5.625

7

2.8125


1

2.8125

8

1.40625

0

Total

210.94

ACTUATORS


Actuators

are

a

subdivision

of

transducers


Actuators

transform

an

input

signal

(mainly

an

electrical

signal)

into

motion
.


It

is

operated

by

a

source

of

energy,

usually

in

the

form

of

an

electric

current,

hydraulic

fluid

pressure

or

pneumatic

pressure,

and

converts

that

energy

into

some

kind

of

motion
.


Actuators

are

used

as

mechanisms

to

introduce

motion,

or

to

clamp

(fix)

an

object

so

as

to

prevent

motion
.

Actuator Examples….


Electrical

motors,


Pneumatic

actuators,



Hydraulic

actuators,



Linear

actuators,



Comb

drive

(capacitive

actuators)


Piezoelectric

actuators



Actuator Examples….

Pneumatic actuators

Hydraulic actuators

Piezoelectric actuators

Comb
-
drives


Comb
-
drives

(capacitive

actuators)

are

linear

motors

that

utilize

electrostatic

forces

that

act

between

two

metal

combs
.



Comb
-
drives

based

actuators

are

specifically

suited

for

large

displacement

application
.


Almost

all

comb
-
drives

are

built

on

the

micro

or

nano
-
scale

and

are

typically

manufactured

using

silicon
.





DRIVES


Driver

is

responsible

to

control

(run

the

process)

the

specific

state

of

any

particular

type

of

device

that

is

attached

to

any

system

(i
.
e
.

motor,

computer)
.



Drives

commonly

operate

and

control

the

direction

and

speed

of

a

specific

device
.


Building Blocks: Drives Versality



AC/DC

servomotors


Stepper

Motors




Induction

Motors




Kinematic

devices




Digital

drives


Hard

Drives


Building Blocks: Drives

AC motors

DC motors

Stepper motors

Digital Drives

AC motors


Motor’s

name

comes

from

the

alternating

current

(ac)

“induced”

into

the

rotor

by

the

rotating

magnetic

flux

produced

in

the

stator
.


Motor

torque

is

developed

from

interaction

of

currents

flowing

in

the

rotor

bars

and

the

stator’s

rotating

magnetic

field
.



AC motors

Stator


Stator

structure

is

composed

of

steel

laminations

shaped

to

form

poles

around

which

are

wound

copper

wire

coils
.



These

primary

windings

connect

to,

and

are

energized

by,

the

voltage

source

to

produce

a

rotating

magnetic

field
.



Three
-
phase

windings

spaced

120

electrical

degrees

apart

are

popular

in

industry
.

Rotor


Rotor

is

another

assembly

of

laminations

over

a

steel

shaft

core
.



Radial

slots

around

the

laminations’

periphery

house

rotor

bars

cast
-
aluminum

or

copper

conductors

shorted

at

one

end

and

positioned

parallel

to

the

shaft


Industrial AC Induction Motors


Industrial

AC

induction

motors

are

designed

to

operate

with

a

current

that

alternates

in

the

direction

of

flow

60

times

per

second

(HZ)
.



If

this

frequency

of

alternation

is

changed,

the

speed

of

the

motor

changes
.



By

controlling

the

AC

frequency

with

a

variable

frequency

drive,

you

control

speed
.


Building Blocks: digital drives


Microprocessors

&

DSP’s

are

replacing

analog

components

with

digital

components

(i
.
e
.
,

digital

drives
)
.



Need

for

A/D

and

D/A

interfaces

is

rapidly

declining,

being

replaced

by

a

high
-

speed

network

between

the

master

host

(a

PC)

and

the

distributed

digital

slave

devices
.




servowire implementation of IEEE 1394

PWM and digital drives

(binary control!)


PWM

(Pulse

Width

Modulation)
-

a

constant

frequency,

two
-
valued

signal

(e
.
g
.
,

voltage)

in

which

the

proportion

of

the

period

for

which

the

signal

is

on

and

the

period

for

which

it

is

off

can

be

varied
.


Percentage

of

time

on

is

called

the

duty

cycle
.


Voltage

value

will

depend

on

the

application
.


PWM

frequency

must

be

high

enough

so

that

motor

cannot

respond

to

a

single

PWM

signal


On

On

Off

Off

T 2T 3T 4T

T 2T 3T 4T

25% duty cycle

50% duty cycle

MACHINE VISION


Machine

vision

(MV)

or

computer

vision

is

the

process

of

applying

a

range

of

technologies

to

provide

imaging
-
based

automatic

inspection,

process

control

and

robot

guidance

in

industrial

applications
.


Machine

vision

is

the

capturing

of

an

image

(a

snapshot

in

time),

the

conversion

of

the

image

to

digital

information,

and

the

application

of

processing

algorithms

to

extract

useful

information

about

the

image

for

the

purposes

of

pattern

recognition,

part

inspection,

or

part

positioning

and

orientation
.


The

main

categories

into

which

MV

applications

fall

are

quality

assurance,

sorting,

material

handling,

robot

guidance,

and

calibration
.


Building Blocks


machine vision

Algorithm

PC

Equipment:



Computer



Frame grabber



Camera (CCD array)



Lenses



Lighting



Calibration templates



Algorithms

Front

Back

Side

Structured

Strobe

Types:

Machine Vision

Machine Vision: structured lighting


Structured

Lighting

is

used

in

a

front

lighting

mode

for

applications

requiring

surface

feature

extraction
.



Structured

lighting

is

defined

as

the

projection

of

a

crisp

line

of

light

onto

an

object
.



The

patterned

light

is

then

used

to

determine

the

3
-
D

characteristics

of

an

object

from

the

resulting

deflections

observed
.


Note

the

non
-
typical

approach

of

projecting

a

grid

array

of

light

on

an

object

to

detect

features

Machine Vision: Image processing


Segmentation
:

Define

and

separate

regions

of

interest
.


Thresholding
:

Convert

each

pixel

into

binary

(B

or

W)

value

by

comparing

bit

intensities
.


Edge

detection
:

Locate

boundaries

between

objects


Feature

extraction
:

Determine

features

based

on

area

and

boundary

characteristics

of

image
.


Pattern

recognition
:

Identify

objects

in

midst

of

other

objects

by

comparing

to

predefined

models

or

standard

values

(of

area,

etc
.
)