Reflecation paper

- Module 8 - Prototyping of Automated Systems

❑ OVERVIEW

• Industrial automation is the control of machinery and

processes used in various industries by autonomous systems

through the use of technologies like Robotics and computer

software.

• Many of the recent products involve some level of automated

devices, such as most electronic devices, appliances, even

toys, etc.

• Automation is a way of increasing productivity by incorporating

tasks and performing them with automatic systems.

1Dr. Munther Hermez

- Module 8 – Cont.

• Automation in a factory can take many forms and can be used in

many areas of a production facility.

• The basic elements of an automated system consist of the machine

instructions or codes and the machines themselves

• The machine instructions are the software that is encoded to tell the

machines how to perform their specific function.

• These machines can perform the same tasks over and over or they

can be programmed to perform multiple jobs.

2Dr. Munther Hermez

- Module 8 – Cont.

> There are four basic elements in an automated system.

• The first element includes the actuators that conduct the

movement of the system.

• The second element includes the sensors that monitor the

environment for action.

• The third element involves the controller.

• The final element is the mechanical system, or mechanism.

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- Module 8 – Cont.

❑ ACTUATORS

• An actuator is a device that performs a mechanical action in

response to an input signal.

• There are three general types of actuators to choose from when

creating an automated process:

- Electric

- Hydraulic

- Pneumatic

4Dr. Munther Hermez

- Module 8 – Cont.

➢ TYPES OF ACTUATORS

• A solenoid is an electromechanical device used to convert electrical

energy into linear mechanical work to push or pull a ferrous plunger

against a nonferrous load.

A typical Soleniode

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- Module 8 – Cont.

➢ DRIVES

Drives or motors are devices that provide continuous movements and

usually rotational motion.

• A servomotor can have complete control of motor position, velocity,

and acceleration.

• A stepping motor rotates through a given angle for every

electrical pulse from the controller.

> The advantages of a stepping motor include the facts that motor

and control boards are small in size and position control is excellent.

>The disadvantages of the stepping motor are that torque control

is limited, motion is not as smooth at low rpm, and calibration is

often needed.

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- Module 8 – Cont.

• A stepping motor rotates through a given angle for every electrical

pulse from the controller.

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(a) One pulse equals one step (b) Pulse count equals step count

- Module 8 – Cont.

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- Module 8 – Cont.

• Selection of Actuators depends on:

1. Cost

2. Function

3. Space

4. Accuracy

5. Power source

6. Related environment

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- Module 8 – Cont.

❑ SENSORS

• Helps the controller detect the changing conditions in a working

environment.

• Sensor classification based on sensor technology can be several

types of sensors, such as:

- Acoustic

- Inductive

- Magnetic

- Electromechanical

- Piezoresistance

- Piezoelectric

- Pressure…etc.

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- Module 8 – Cont.

• Manual Switches

In automation, binary sensors or switches are commonly used to

detect the presence of an object.

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Some limit switches, including push button type and rotating type.

- Module 8 – Cont.

• Proximity Switch

Detect the presence of an object using inductive, magnetic, or

capacitive properties.

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Some examples of proximity switches.

- Module 8 – Cont.

• Photosensor

Are photocells used to detect the presence of light radiating naturally

from some object in the process

• Fiber Optics Sensor

use fiber optics in combination with the photosensors to bend light

around corners or to achieve more accurate results.

• Infrared Sensor

Can detect heat, which is an infrared radiation.

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- Module 8 – Cont.

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Using fiber optics to stop the boat in a precise location for robotic painting.

- Module 8 – Cont.

➢ SENSOR SELECTION

The sensor selection steps are summarized in the flow chart:

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- Module 8 – Cont.

❑ CONTROLLERS AND ANALYZERS

• In order to control a process, a controller is needed.

• A controller can be a simple analyzer such as counter, timer, or bar

code reader; programmable logic controller (PLC); or a computer.

• Controllers / Analyzers main functions to process are:

> Receive process inputs

> Register and analyze inputs

> Output responses to the process

16Dr. Munther Hermez

- Module 8 – Cont.

• A PLC is a digital operating electronic apparatus.

This cyclic controller receives input, analyzes, and outputs

continuously as shown in Figure:

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- Module 8 – Cont.

➢ PLC CONTROL

• The main function of a PLC is to control automated processes in a

system.

• A PLC is designed to track a large number of inputs and issue a

large number of commands in a very short amount of time

(milliseconds).

• A PLC uses a symbolic programming language that makes it

simple for the programmer to modify the way that the outputs are

sent based on the input signals.

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- Module 8 – Cont.

The PLC selection steps are listed in the Figure:

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- Module 8 – Cont.

➢ COMPUTER CONTROL

• Computer control could be in various levels:

(1) Hardware level, such as to turn on the disk motor.

(2) Basic input-output system (BIOS) level, which consists of a

collection of programs that control the hardware.

(3) Disk operating system (DOS) operating system level, such as to

save a file to the disk.

(4) Application level, such as to replace a file on the disk in

WordPerfect with an equivalent file in Word.

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- Module 8 – Cont.

❑ MECHANISMS

Mechanisms cover a broad area that ultimately provides the action or

enables the action to take place for the automation sequence.

Classifications of mechanisms

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- Module 8 – Cont.

▪ MECHANISMS IN AUTOMATION

• The factors that dominate a mechanical design are:

1 - Cost

2 - Space constraints

• The space constraints include transmitting direction and

transmitting distance.

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- Module 8 – Cont.

> forward transfer when the vector of the axis of the input motion is

the same as the vector of the axis of the output motion.

> Backward transfer is similar except that the purpose is to provide

a returned motion.

> Parallel transfer is when the vector of the axis of the input motion

is parallel to the vector of the axis of the output motion.

> Angular transfer is when the vector of the axis of the input motion

has an angle with the vector of the axis of the output motion.

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- Module 8 – Cont.

• Four basic types of transformations are specified:

1st. linear to linear

2nd. linear to rotary

3rd. rotary to linear

4th. rotary to rotary transformations.

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- Module 8 – Cont.

• One of the sub function trees of these transformations shown in the

figure.

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▪ APPLICATIONS AND SELECTION OF MECHANISMS

Main commonly used mechanisms and mechanical components

are further illustrated below:

1- Linear or Reciprocating Input, Linear Output

2- Rotary Input, Rotary Output

3- Rotary Input, Reciprocating Output

4- Rotary Input, Intermittent Output

5- Rotary Input, Irregular Output

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- Module 8 – Cont.

6- Reciprocating Input, Rotary Output

7- Reciprocating Input, Oscillation Output

8- Reciprocating Input, Intermittent Output

9- Reciprocating Input, Irregular Output

10- Oscillation Input, Rotary Output

11- Oscillation Input, Reciprocating Output

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- Module 8 – Cont.

12- Oscillation Input, Intermittent Output

13- Oscillation Input, Irregular Output

14- Rotary Input, Linear Output

15- Other Complex Motions

16- Universal Joint Mechanisms

17- Wedges and Stopping

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