Transcript Standard Grade Computing

Standard Grade
Computing
Automated Systems
What is an Automated System
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When computers are used to
control a system consisting of
machinery and equipment.
Examples of Automated
Systems
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washing machine
central heating system
video recorder
microwave oven
controlling machinery in a factory
traffic light control
aircraft guidance
Why use Automated Systems?
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faster than a humans
do boring and repetitive jobs
accurate - don’t make mistakes
efficient – don’t need breaks
can be used in dangerous situations
flexible - can be programmed to do
different tasks
Stationary Robots
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Stay in one place all the time
e.g. used on factory assembly lines
Control programs are stored on disc
or tape
Can be reprogrammed to do a
different task
Anatomy of a Robot Arm
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Some robots have parts that
resemble human limbs
A jointed robot arm has a
Shoulder
Elbow
• waist
• shoulder
• elbow
Waist
• wrist
• hand (specialised to suit the robot’s
task)
Wrist
Degrees of Freedom
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The number of degrees of freedom
is the number of ways the arm can
move.
To work in three dimensions the arm
must have at least three degrees of
freedom.
The human arm has eight degrees of
freedom.
Degrees of Freedom
ROTATE BASE OF ARM
PIVOT BASE OF ARM
BEND ELBOW
WRIST UP AND DOWN
WRIST LEFT AND RIGHT
ROTATE WRIST
End Effectors
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The ‘hand’ of the robot arm is
specialised to the task the robot is
programmed to do.
The ‘hand’ could be a
• gripper
• paint spray gun
• welding electrode
• suction cap
• paint stripper
• magnet
Mobile Robots
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Robots which move are called
mobile robots.
The robot Dante walks into
volcanoes.
In 1994, NASA, Carnegie Mellon
University and the Alaskan
Volcano Observatory used
satellite and Internet
connections to manoeuvre
Dante into the active crater of
Mt. Spur, an Alaskan volcano 90
miles west of Anchorage.
Mobile Robots
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Nomad is a four wheeled
robot that has been
looking for asteroids in
Antarctic.
Nomad was built to
explore the Antarctic in
search of new meteorite
samples in January 2000.
Nomad spent nearly two
weeks in the Arctic frost,
examining over 100
indigenous rocks and
ultimately classifying
seven as bona-fide
meteorites.
Automated Guided Vehicles
Remote-operated Vehicles
Underwater
ROV’s
Computer Aided Design
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Buildings
Cars
Motorways
Mobile Phones
Circuit Boards
Processors
Benefits of CAD
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Easier to produce complex drawings
Making changes to design is easier
Can make multiple copies
Can use library shapes
CAD Hardware
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High resolution
monitor
Powerful processor
High capacity
backing storage
Graphics tablet
Graphics plotter
Computer Aided Manufacture
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Use of computers to control
machinery in the production process
Car manufacture
Fabric cutting in making clothes
Fitting components to circuit boards
CADCAM
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Objects are designed using CAD
Design is fed to the controlling
computer
Robots and machines assemble the
product
Benefits of CADCAM
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Faster process
More accurate process
Less waste
Increases productivity
Higher quality end product
Effects of CADCAM
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Machines have replaced people
Fewer jobs
Remaining jobs have become
deskilled
More jobs for computer programmers
and engineers
Simulation
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A computer mimics a real world
activity
Flying a plane
Driving a car
Crashing a car
Performing surgery
Computer games
Virtual Reality
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The user is immersed in the
computer generated world
Virtual reality headsets/helmets
Sensory gloves
Intelligent Robots
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Have a range of sensors
Mimic the human senses and
functions
Hear : microphone
See : sonar beams / optical sensors
Feel : tactile/pressure sensors
Walk : Human-like legs
Asimo
Robots in the Future
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Hovering the house
Ironing
Open Loop Control
Control computer
Control Information
Closed Loop Control
Feedback from sensor
Control computer
Control Information
Traffic
Sensor
Sensors
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A sensor detects physical quantities
e.g. heat, and provides this input to
the controlling computer.
Types of Sensors
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There are sensors to detect
• heat
• light
• collisions
• proximity
• magnetic fields
• pressure
Analogue Signals
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Most electrical signals are analogue
signals.
Analogue signals vary continuously over
time.
They can have any value between the
upper and lower limits.
Digital Signals
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Computers can only work with
digital signals.
Digital signals have only two
values - on or off.
Signal Converters
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A computer is connected to a device by a
circuit called an interface.
The interface must be able to convert the
computer’s digital signals to analogue signals
if required.
This is done by a digital to analogue
converter.
Signals can be changed in the other direction
by an analogue to digital converter.
A transducer is a device which changes a
physical input e.g. heat, pressure or light into
an analogue signal.
AD Converter
Sensor
+
(transducer)
Analogue to
Digital Converter
Processor
DA Converter
Processor
Digital to
Analogue
Converter
Device
Teaching Robots
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Programming by Example (lead-through)
• a human guides the robot
• the positional sensors in the robot tell the
computer about the movement of each joint
• the robot’s actuators (motors) repeat the
stored sequence of movements.
Teaching Robots
Programming Robots
• a programmer works out the whole
sequence of movements and describes
them in a high level language
• writing a new program will enable the robot
to do a different task.
Control Languages
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Computer programs are always written
in a programming language.
You have learned to program in Visual
Basic.
Most robots are programmed to move
using a special control language.
They use meaningful commands like
forward, right, left, wait, grasp, up
and down which relate to the robot
world.
Control Programs
Disc/Tape
 Stationary robots may have the
control program stored on disc or
tape.
 Can be changed easily.
Control Programs
ROM Chips
 Mobile robots are more likely to have
the program stored on a ROM chip.
 Chips are more expensive
 More permanent
 Give a faster start up
Social Implications
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Disadvantages
• workers will lose their jobs.
• Some jobs may become deskilled and offer less job
satisfaction
Social Implications
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Advantages
• workers can be retrained to do more
interesting and skilled jobs.
• fewer people work in dangerous
factory conditions.
• workers who did boring jobs will have
more leisure time.
• jobs will increase in the computing
and leisure industries.
Technical Implications
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Safety
• moving parts of machine must be covered.
• robot vehicles have sensors to detect if
anything is in the way
• they can be programmed to move slowly so
that people can get out of their way
• people are kept out of some areas of the
factory
• robot arms etc. should only operate when an
item is in position
Economic Implications
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Automated Systems are Capital Intensive
• very expensive to install
• but don’t demand wage rises
• don’t require lunch breaks
• don’t require canteens and toilet facilities
• money will be saved in the long term
Factories used to all be Labour Intensive
• large number of workers required
Increased Productivity
• more goods manufactured in the same time for
the same cost