COMPUTING THEORY – 3. Control

What are physical systems?

Physical systems include robotics, motors and sensors. Examples include street lights that switch on automatically at night, remote controls, traffic lights that automatically control the flow of traffic on our roads, security systems such as burglar alarms that sound an alarm when they detect an intruder, air conditioning systems, automatic doors, and much much more!

Why do we use physical systems?

We use physical systems for many different reasons.

They enable us to explore places that humans can’t work. For example, robots exploring new frontiers, like Mars. In places where humans can’t actually survive, computers can help explore for us.

They also enable us to simulate environments that are not safe for us. For example, a flight simulator can help someone learn to fly and experience different situations without the risk of crashing. This is also much cheaper than doing it for real.

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Machines can also work more quickly and for longer periods of time. They do not need breaks or holidays, and can work 24 hours a day, 365 days a year. They are also less likely to make mistakes.

Computers and sensors

Computers and sensors can be used to control conditions in lots of different places.

You might have sensors in your home to control the lights. When light sensors detect that it is dark outside a computer can instruct the lights in your driveway to switch on.

Traffic lights are another example. A computer responds to sensors on a camera, checking to see if cars are waiting. If they are, the lights are changed according to a set pattern.

How do control systems work?

Computers can only interact with the world if they are connected to input and output devices. These devices allow them to respond to the world around them and to act according to their programming.

A computer can be programmed to respond to input devices like sensors. For example in a water heater, sensors are used to react to a drop in temperature and tell an output device, like a heating element, to heat up the water. This is how our central heating system at home works too.

What is a robot?

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