Understanding Technology with Systems Approach & Control Diagrams, Study notes of Engineering

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Engineering

Systems and Control

Name

Class

Teacher

Learning Intentions

o To learn about the different roles of engineering o To learn about the varied role of Engineers in designing, implementing, testing and controlling complex systems o To learn the effects that engineering has on the world o To know about control diagrams for simple control systems o To learn about what the systems approach is o To learn about subsystems o To learn about energy forms o To learn about basic energy transformations o To know about open loop & closed loop control o To know what a feedback loop is o To learn what an error detector is and how its used in a control system

Success Criteria

o I can identify and describe different branches of engineering o I can explain how emerging technologies can provide improves solutions to engineering challenges o I can describe examples of social, environmental and economic impacts of engineering o I can draw and understand a system diagram, showing inputs and outputs o I can describe, using the systems approach, how some simple engineered objects work o I can identify basic energy transformations o I can identify the main sub-systems of an object o I can draw and understand sub-system diagrams o I can understand and create diagrams for simple control systems o I can understand the difference between automatic and manual control o I can understand how an error detector is used within control systems

To access video clips that will help on this course go to www.youtube.com/MacBeathsTech

Task 2 Choose an engineering challenge from the list below

 New Forth Road Crossing  Virgin Galactic  Google Car  Offshore Wind Farms

You are to produce a PowerPoint on the engineering challenge, by completing the following tasks.

(a) Describe how several different branches of engineering all contribute to the successful completion of this project. You should refer to civil, mechanical, electrical, chemical and at least 1 more form of engineering.

(b) Describe some example tasks that engineers would do while working on this project. These should include:

 design tasks  implementation tasks  testing  the controlling of the complex systems

(c) Describe how two recent or current technological developments are making it possible to improve solutions to this engineering challenge.

Task 3

Review the engineering challenge that you have been investigating.

You are going to produce a report entitled ‘The Impacts of Engineering’, by completing the following tasks.

(a) Describe one positive and one negative social impact resulting from an engineering project or challenge

(b) Describe one positive and one negative economic impact resulting from an engineering project or challenge

(c) Describe one positive and one negative environmental impact resulting from an engineering project or challenge

(d) Describe at least two examples of how engineering solutions are contributing to tackling climate change.

Task 4 A prototype solar panel is being tested. Describe the role of the following engineers in the development of the Panels (a) An Electronic Engineer

(b) A Mechanical Engineer

Task 7 Read the following statements. After each one put a T or F to say whether you think it is TRUE or FALSE.

Technology is only about electronics.

Women cannot understand technology.

Technology is about solving problems.

Cars use technology but windmills don’t.

People have always used some form of technology.

The world would be a better place without technology.

Everybody is affected by technology.

Only scientists use technology.

Cavemen did not use technology.

Task 8 Copy and complete the sentence below putting each of the 5 words listed in an appropriate place in order to reach a definition of technology that we will use for this course.

LIVES; MAKING; RESOURCES; PROBLEMS; KNOWLEDGE.

Technology is about ………………… things by using …………………… and ………………… to solve …………………… in an attempt to make our ………………… better.

Task 9 In your lifetime Technology has advanced tenfold. If you even think of the advancements that have been made in computer games since you first played them.

Your task is to pick an everyday piece of technology and create a timeline poster. The poster must show how it started and it has progressed throughout the years.

Tomb Raider

http://www.youtube.com/watch?v=1rPAO_kzirc

Task 10 Copy and complete the block diagrams below by adding the correct inputs and outputs.

Extension Some of these systems can have more than 1 input or more than 1 output. Add anymore you can think of to your block diagrams.

Doorbell

Windmill

Table lamp

CD player

TV

Hair dryer

Energy

Energy is needed to make things work.

ENERGY can be CONVERTED from one form into another by a suitable PROCESS.

Listed below are the main forms of energy:

Sound Heat Light Electrical Chemical Nuclear Magnetic(field) Kinetic (movement) Potential (stored)

Take our example of the car from before its input is petrol which is a type of CHEMICAL ENERGY. Its output is movement which is KINETIC ENERGY.

One form of

energy IN

Different form of energy OUT

Chemical Car Kinetic

Sub-Systems

The Universal System is OK for working out how technology works, but to use technology to solve problems we must break it down even further to get a greater understanding of it. To do this, we use a sub-system diagram as shown below.

The sub-system diagram shows theinternal detail of the system. Each

box, called a sub-system, can be thought of as a system within a system and has its own input and output. The dashed line around the sub-system is called a system boundary and this marks the area of interest to us. The ‘real world’ input and output are shown as arrows entering and leaving the sub-system diagram.

By using a sub-system diagram it shows more detail of how a system works. For example A set of Hair Straighteners

By doing a universal diagram not much information can be gathered on how the system actually works. By breaking it down into a sub-system diagram, it is clearer how the technology works.

Input Sub-system

Process (control) Sub-system

Input Output

System Boundary

Output Sub-system

Hair Electricity (^) Straighteners Heat

On/Off Switch

Electricity Heating Heat Element

Ceramic Plates

Task 12

1. Draw a sub-system diagram for the following:

(a) Torch

(b) Vacuum cleaner

(c) Kettle

(d) Toaster

2. Draw a sub-system diagram for a house alarm with a door sensor,

panic button, keypad arm, control unit, siren and strobe-light

alarm.

Types of Control

Along with Automatic and Manual control, we also normally consider the type of control the system provides. There are two types of control:

 open-loop control  closed-loop control

This is an example of manual open-loop control for running a bath. The bath continues to fill, and will eventually overflow, because nobody is there to check the system turn off the tap.

This is an example of a manual closed loop control for running a bath. The baths runs, but because someone is there to check the system ensuring nothing goes wrong, the bath will not overflow.

tap handle

tap valve

bath level

Water Person

Flood

tap handle

tap valve

bath level

brain eyes (control)

hand

Water Bath Ready

Open Loop Control

At the simplest level a control system can process an input condition to produce a specified output. This is the simplest acceptable level of control. It is also the most common form of control system, used widely in domestic and industrial systems because it is cheap to install and simple to operate.

An example is a hair dryer. The input is the action of pressing the button and the output is the hot air.

A system diagram for a hair dryer is shown below.

Here the input signal from the on/off and temperature switch is processed to produce the output. The output air is not monitored or adjusted in any way and it is just blown out at whatever temperature the heater warms it to.

An open-loop control system is the simplest and cheapest form of

control. However, although open-loop control has many uses, its basic weakness lies in its inability to adjust the output to suit the requirements.

Light Switch

Lamp Filamen tt

Glass Bulb

Action

heat^ Light control sub-system

heating element

Heater only on when switched on

motor fan

on/off control sub-system

Switch on Electrical energy

Set temperature level

Cold Air

Hot Air

Sound Energy

Task 13

Draw a sub-systems diagram for a fridge with a thermostat, control unit, coolant pump, door switch and light.

Task 14

1. State three examples of manual open-loop control. Draw a system diagram for each one and show the system boundary.
2. State three examples of manual closed-loop control. Draw a system diagram and show the system boundary.
3. State three examples of automatic closed-loop control. Draw a system diagram and show the system boundary.

Control Diagrams

The purpose of closed-loop control is to ensure that the output is maintained at, or as closely as possible to, the desired level. For example, the temperature is set on a dial on the control panel of a cooker will be a closed loop control. A temperature sensor constantly monitors the output (oven temperature) and produces a signal representing the

actual temperature.

The actual signal is fed back to a control element, which compares it

with the set signal. Any difference between set and actual signals

produces an error signal. This causes the control element to either

decrease or increase the input (gas flow) in order to reduce the temperature error to zero.

The control unit shown in the system diagram above performs two functions.

 The set and actual values are compared.  Any resulting error is used to vary the input sub-system as required.

inlet valve burner oven

control unit

temperature sensor

Gas

Set Value

Actual Value