Traffic lights, automatic doors and central heating systems are
just three examples of control systems we have explored in this
unit of work. Computers can control all of these things, and many
others. But how do automatic doors know they should open?
There needs to be these three things present:
Input
UNIT REVIEW
Getting
information
into the
computer
Process
Output
Instructions for the
computer to do something
with the information
The result
alters
something in
the outside
Open
Loop
world
The two types of control systems we looked at were
and Feedback. Use the slides below to identify two important
facts about each system.
Open Loop
NAME:……………………………………………………
CLASS:……………………………
Feedback
1.
2.
1.
2.
Examples of Control Systems
We have identified many different examples of computer control
systems that we see and use in every day life, eg., a car remote
control security system. See if you can list three more examples
of computer control systems:
1. …………………………………………………………………………………………………………………
2. …………………………………………………………………………………………………………………
3. …………………………………………………………………………………………………………………
Advantages & Disadvantages
Now, using the three examples of computer control systems you
listed above, think of three advantages and three disadvantages
of using computer control systems for each one:
My first example is:
Advantages
1
2
3
My second example is:
Advantages
1
2
3
My third example is:
Advantages
1
2
3
Disadvantages
Disadvantages
Disadvantages
Control Systems Test
 Tick the box with the right answer:
1. Which one of these is a type of control system?
 Broadband
 Open Loop
 Closed Loop
 Open circuit
2. A microwave oven is a type of open loop system.
 True
 False
3. A greenhouse uses which type of sensor?
 Infra-red
 Pressure
 Bump/touch
 Humidity
4. A computer-controlled robot uses which type of sensor?
 Bump/touch
 Humidity
 Pressure
 Heat
5. In Logo, which command will move the turtle forwards 5
units?
 F5
 Forward 5
 FD5
 FD 5
6. In Logo, which command will turn the turtle 90 degrees?
 RT3
 Right 90
 R9
 RT 90
7. In Logo what shape would these commands produce –
REPEAT 4 (FD 50 RT 90)
 Square
 Circle
 Triangle
 Rectangle
8. Which one of the following is NOT an advantage of control
systems?
 Can be used in dangerous places
 Can operate without a break
 Expensive to buy and install
 Can repeat tasks over and over again
9. What does a feedback loop use to control the output of a
device?
 Computer
 Information
 Data
 Infra-red
10. Feedback systems are more flexible than open loop
systems.
 True
 False
11. Feedback systems only measure the input data.


True
False
12. A central heating system is an example of a control
system.
 True
 False
Flow Charts
System flowcharts are a way of displaying how data flows in a
computer-controlled system, and how decisions are made to
control events. There are lots of different symbols used. Basic
ones include:
On the next page is a
flow chart for making a
cup of tea. However the
commands are missing
from the flow chart
symbols. Use the
answers provided on the
left hand side of the
page to fill in the
symbols. The first one
has been filled in for
you already.
Write the following
instructions into the
flowchart in pencil, in the
order they are carried out
to make a cup of tea.
Start
Glossary of Terms
Here is a list of key words from the unit. Use the Definition
column to write a meaning for each. The BBC website will help
you. Follow this address to get to the right page:
Kettle boiled?
http://www.bbc.co.uk/schools/gcsebitesize/ict/measurecontrol/index.shtml
Milk?
Add milk?
Wait
Add sugar?
Stir
Yes
No
Stop
Fill kettle with water
Switch on
No
Yes
Pour water into cup
Sugar?
Put tea in cup
No
Yes
No.
Key word
1
Analogue
2
Control program
3
Digital
4
Feedback cycle
5
Floor roamer or
Turtle
6
Input
7
Interface box
8
Logo
9
Loops
10
Output
11
Processor
12
Sensors
Plug kettle in
Start
Definition