Control Systems The Control Room of a Nuclear Power Station
Dec 29, 2015
Control Systems
The Control Room of a Nuclear Power Station
A control system is a system of hardware and software that controls the function of a piece of equipment, e.g. a radio controlled car is an example of a basic control system. Other examples include…
Traffic Lights
Lifts
Microwave
Air Conditioning Systems
Theme Park Rides
Automatic Doors
Burglar Alarm
Train Networks
Robots
What is a Control System?What is a Control System?
Security Lights
In their simplest form, control systems take in data as input, process the data, and then send out signals as output…
The Parts of a Control SystemThe Parts of a Control System
In their simplest form, control systems take in data as input, process the data, and then send out signals as output…
The Parts of a Control SystemThe Parts of a Control System
There are two main types of control system…
Open LoopSystem
Closed LoopSystem&
Types of Control SystemTypes of Control System
The open loop system is the simplest type of control system, as it does not take account of the output. The input data is processed, then sent as output,e.g. an automatic door…
Open Loop SystemOpen Loop System
A person stepson a pressure pad,
and the pressure pad sends a signal tothe control box
The control box processes the
data, and sendsa signal to the electric door
The door opens in time for the person
to walk through
Open Loop SystemOpen Loop System
The open loop system is the simplest type of control system, as it does not take account of the output. The input data is processed, then sent as output,e.g. an automatic door…
A person selects the microwave power and the time for
cooking. This input is sent to the
embedded computer
The embedded computer
processes the data, and sendsa signal to the
microwave generator
The microwave generator cooks the food for the required time at the required
power
Open Loop SystemOpen Loop System
Another example of an open loop system is the control system for a microwave oven…
The problem with this open loop system is that the microwave oven will keep cooking the food, even ifit is already burnt – there is no account of output.
A closed loop system uses feedback provided by sensors. Feedback is where information from the output gets used as part of the input. A feedback loop provides extra data, which is processed withthe input data.
Closed Loop SystemClosed Loop System
Closed Loop SystemClosed Loop System
A closed loop system uses feedback provided by sensors. Feedback is where information from the output gets used as part of the input. A feedback loop provides extra data, which is processed withthe input data.
The pilot operates the control to put the aircraft into a
steep turn.Feedback also forms
part of the input.
The plane’s control box (a large computer)
processes this data and sends signals to the
wing flaps and engines.
The wing flaps and engines make the
necessary adjustments.
Most control systems are closed loop systems, e.g.a flight control system…
Sensors monitor the tilt of the aircraft and send this information to the control box. This becomes part of the input. When the required amount
of tilt has been reached, the computer sends signals to thewing flaps and engine to stop any further adjustments.
Closed Loop SystemClosed Loop System
Timings are set at the control box for
the heating to come on and off, and the thermostat on the
wall is turned to the correct temperature.Feedback from the thermostat forms part of the input.
The control box processes these
settings and sends signals to the boiler
and water pump.
The boiler and water pump operate
together to warm the house to the
correct temperature.
Another example of a closed loop system is a central heating system…
The thermostat is a heat sensor which detects the temperature in the room. The thermostat sends signals to the control box, which will
switch the water pump off if the house is warm enoughand on, if the house is too cold.
Closed Loop SystemClosed Loop System
What different control systems might there be onboard this yacht?
Engine Management
Air conditioning
Navigation
Control TechnologySome of the most advanced control technology is used in cars and airplanes.
Control TechnologyControl Technology
This car’s control systems include:
ABS (Anti-lock Braking System)
Engine Management
Rain detecting windscreen wipers
Darkness detecting headlights
Anti-lock Brake SystemAnti-lock Brake System
Draw an input-output diagram for the flow of data in an anti-lock brake system…
The driver applies the brakes firmly in an emergency.
Feedback fromthe sensors in the wheel also forms part of the input.
The control box processes the data and
either allows the braking to go ahead or sends a
signal to the calliperto release a wheel.
The calliper either grabs or releases the wheel and the car slows down as quickly as possible without skidding.
Sensors monitor the motion of the wheels. If any of the wheels stops turning, i.e. starts skidding, the control box sends a signal to the brake calliper to release the brake on that wheel for a fraction
of a second, just until the wheel starts turning again.
Rain-detecting Windscreen WipersRain-detecting Windscreen Wipers
Draw an input-output diagram for the flow of data in a rain-detecting windscreen wiper control system…
Sensors in the windscreen detect the moisture level
and send data to the control box. The driver may alsoset the wipers
manually.
The control box processes the data and sends a signal to the windscreen wipers,
controlling the precise speed of movement.
The wipers move at a rate which
removes the water efficiently, whilst distracting the driver as littleas possible.
Sensors in the windscreen continue to send data to the control box, e.g. if the car slows down, less rain will hit the windscreen so the moisture
level will go down. This data is fed back to the control box,which would then slow down the wipers.
Fly-by-Wire
Fly-by-WireFly-by-Wire
Fly-by-wire is a complex control system that controls and monitors:
Thrust (force produced by the engine)
Lift (upwards force produced by the wings)
Pitch and yaw (the tilt of the aircraft)
Flight plan (weight, destination, route, weather conditions)
Fly-by-WireFly-by-Wire
Fly-by-wire creates a huge amount of data which is passed from sensors, to the onboard computerto be processed, then onto the output devices.
The computer processes the pilot’s instructions from the joystick and other cockpit controls, then sends signals to the rudders, engines and wing flaps inorder to achieve the desired results.
There are no physical links, such as cables from the cockpit directly to the rudders, engines, etc.
Fly-by-WireFly-by-Wire
If the pilot pulls too heavily on the joystick, thesystem may issue a warning to the pilot, or override the pilot’s instruction, to prevent an accident.
Modern aircraft are so complex, that it would not be possible tofly them withoutfly-by-wire technology.
Control systems can work 24 hours a day, 7 days a week. They don’t need a break, they don’t complain and they don’t need paying – unlike humans.
Advantages of Control SystemsAdvantages of Control Systems
They can be relied upon to respond quickly and precisely to data from many different sensors at the same time.
They can be used in inhospitable and dangerous situations, e.g. inside Nuclear power stations.
The software and hardware can be expensive because it may have to be produced specifically for a particular job.
Disadvantages of Control SystemsDisadvantages of Control Systems
If a computer fails, the whole system will fail. For this reason, important control systems, such as fly-by-wire, or those inside a nuclear power station, are protected with emergency backup systems ready to take over in case the main system fails.
The computer cannot react to unexpected events, only those events which have been programmed in, whereas a human would be able to take action.
Keyword Activity 1Keyword Activity 1
Drag the missing words to the correct place in the sentences…
Keyword Activity 2Keyword Activity 2
Drag the missing words to the correct place in the sentences…
WordsearchWordsearch
CrosswordCrossword
QuizQuiz
After viewing this presentation, you should…
Understand the terms control system, input, processing and output.
Understand the difference between an open loop system and a closed loop system.
Be able to list several examples of computer controlled systems, e.g. traffic lights, burglar alarm.
Be able to describe feedback.
ObjectivesObjectives
Be able to draw input-output diagrams to explain what happens at each stage of input, process, output and feedback for common control systems.
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