UNIT 3 – MONITORING AND CONTROL
Year 12 IT
KEY TERMS
Sensor: a device that records data about the surrounding physical environment
Input device: a device that allows data to be entered into a computer system
Analogue: this is the smooth stream of data that we process on a daily basis
Microprocessor: an integrated circuit used in monitoring and control technologies
Actuator: this is a type of motor that controls a mechanism or system
Infrared: a wave of light emitted by an object that is invisible to the naked human eye
Microwave: an electromagnetic wave of energy Piezoresistance: a specific level of
electrical charge that is linked to a specific level of resistance or pressure Humidity:
the amount of water in the atmosphere Photoresistor: a light controlled resistor
TIP
T
Sensors can automatically enter data
into a computer system, removing the
need for a human to manually enter
the data.
They can be very beneficial as it can
increase the accuracy of the data by
removing the possibility of human
error.
Remember
 Control technologies use sensors to
automatically control elements of a system,
or a whole system, by using the data from
them to trigger an action or event.
:
UNIT 4 - eSECURITY
Year 12 IT
3.1 Sensors
USES OF MONITORING TECHNOLOGY
*Weather stations
Temperature sensors
Pressure sensors
Humidity sensors
Light sensors
A tripping bucket and a reed switch
Learning Objectives:
In this chapter you will learn:
• About the sensors and
calibration used in monitoring
technologies
• About the uses of monitoring
technologies
• About the sensors and
actuators used in control
technologies
• How to write an algorithm
and draw a flowchart
Figure 3.1a - CCTV security cameras
Advantages and disadvantages
Figure 3.1b - A car park barrier
:
UNIT 3 – MONITORING AND CONTROL
Year 12 IT
3.1 Sensors
Motion Sensors
A motion sensor detects movement
Pressure Sensors
Pressure sensor measures pressure,
normally of a liquid e.g. gas.
Moisture and Humidity Sensors
Temperature Sensors
Temperature sensors monitor and
measure the temperature of an
environment
Light Sensors
Light sensors monitor and measure
light
Actuators
Controls a device such as the valve
which allows water to flow through
heaters or sprinklers in a greenhouse
Weather stations use temperature
sensors to measure ambient
temperature,
pressure sensors to measure
atmospheric pressure,
humidity sensors to measure
absolute and relative humidity,
light sensors to measure sunlight
Examples of other uses including:
monitoring water pollution,
weather stations, environmental
monitoring
UNIT 4 - eSECURITY
Year 12 IT
1.2 Calibration
Calibration is the setting or correcting
of a measuring
device or base level,
usually by adjusting it to match
or conform to a
dependably known and unvarying
measure (standard).
 Calibrating a device ensures its
accuracy when collecting data.
 Computer software may also
offer calibration features to
optimize its use of your
computer's hardware
LESSON OBJECTIVES
•
•
The importance of calibration
The various methods used to
calibrate devices, including
when to use one point
calibration, two point
calibration and multi-point
calibration, knowing methods
of calibrating readings from
sensors such as temperature
sensors
UNIT 4 - eSECURITY
Year 12 IT
3.2 Control Technologies
Touch sensors incorporated within
detection devices used to measure
fluid levels (cooling water level in
Moisture sensors to measure water
content of soil
Infrared sensors to detect movement
of human bodies, which emit heat, in
burglar alarm systems
Electromagnetic field and ultrasonic
sensors in car parking systems
Sound sensors in burglar alarm
systems to detect the level of sound
an intruder might make
Proximity sensor in smartphones to
switch off screen display when phone
is held near to the ear
Learning Objectives:
In this chapter you will
learn:
To evaluate the use of monitoring
technologies in everyday life
(including: CCTV monitoring,
environmental monitoring,
workplace monitoring)
evaluate the use of control
technologies in everyday life
(including: household appliances,
car park barriers, traffic light
RESOURCES
The following websites contain information
about control/monitoring systems:
http://home.howstuffworks.com/ac2.htm
http://home.howstuffworks.com/refrigerator1.ht
m
http://electronics.howstuffworks.com/robot3.ht
m
http://blogs.howstuffworks.com/transcript/howdoes-a-traffic-light-detect-cars.htm
THE ROLE OF SENSORS
UNIT 4 - eSECURITY
Year 12 IT
3.2 Control technologies
Examples of control technology
systems include:
•
•
•
•
•
•
•
•
•
Microprocessor controlled –
glass/greenhouses
central heating systems
air conditioning systems
burglar alarms
control of traffic/pedestrian flow
car park barriers
traffic lights
Wireless Sensor and Actuator
Networks
smart homes
Learning Objectives:
In this chapter you will
learn:
To evaluate the use of monitoring
technologies in everyday life
(including: CCTV monitoring,
environmental monitoring,
workplace monitoring)
evaluate the use of control
technologies in everyday life
(including: household appliances,
car park barriers, traffic light
RESOURCES
The following websites contain information
about control/monitoring systems:
http://home.howstuffworks.com/ac2.htm
http://home.howstuffworks.com/refrigerator1.ht
m
http://electronics.howstuffworks.com/robot3.ht
m
http://blogs.howstuffworks.com/transcript/howdoes-a-traffic-light-detect-cars.htm
https://learnlearn.uk/alevelcs/monitoring-control-systems
/
Monitoring and Control 3
3.3 Algorithm
An algorithm is a sequence of instructions that are
followed step-by-step to solve a problem. This does not
need to be on a computer
Algorithm for Car Park Barrier Control:
Start
Initialize system (e.g., set the barrier to the closed
position)
Repeat the following steps:
4. Wait for a trigger event (e.g., a car approaching the
barrier)
If the trigger event is detected, then do the following:
6. Check if the barrier is already open:
If the barrier is open, wait for the car to pass
Close the barrier once the car has passed
If the barrier is closed, open the barrier
End the condition
End the loop
Stop the system
End
Learning Objectives:
Candidates should be able to write a basic algorithm
that demonstrates a decision making process