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Sensors and actuators

Dr Steven Houben explains how the devices use real world energies to transform digital information into physical phenomena in the real world.
So the first type of transducer that we’ll be looking at is the input transducer or the sensor. A sensor essentially is a device that allows us to sense the world around us. It does this by capturing physical energy, activity, or expression and converting this into digital data. So that means that input can be considered anything that allows us to kind of convert aspects of the real world into units or information that can be read, processed, and stored by a computer.
Examples of sensors are button presses where we want to detect whether a user is touching the button, but also a light sensor that allows us to detect whether it’s light or dark, proximity sensor to see how far things are apart. We can also measure things about our body, for example the heart rate. And other examples are temperature, speed - but there’s actually many, many more things we could sense around us. At its essence, an input transducer or a sensor essentially converts physical energy in the world around us into digital information that can be stored in a computer. So here’s a small example of a sensor.
This is a light sensor that can actually detect a light value once it’s plugged into a computer, obviously. This is an example of a proximity sensor. So it uses these two lenses to kind of project infrared light and see whether something is close to the sensor. Here we have a small humidity and temperature sensor that could, for example, be used for a weather station that essentially collects information about humidity in a room or even outside, and the temperature as well, and it merges that data together. This is an RFID reader, which is a classic device that is used to read, for example, your student cards or any other type of access card that you might want to use.
And this is an example, obviously, of a simple button that we can use to detect whether someone someone’s pressing or basically touching the device. And this is the sort of more advanced input device called a rotary encoder, where we can actually select a value by rotating it. So the second type of transducer that we’ll be looking at are output transducers or actuators. And actuators are essentially devices that allows us to change the real world to communicate information or to trigger some sort of input in the real world. We do this through visual means like an LED or a screen. It can be auditory like a buzzer or a speaker. It can be robotics like movement or a robot arm.
It can be olfactory smells or haptic, where we have very directed vibrations. What an output transducer is doing is essentially taking digital information in the computer and changing it into physical phenomena that manifests itself in the real world. So essentially, we produce direct output from the computer to one of these physical devices that kind of convert the digital information into physical energy. So the first and classic example of an output transducer is essentially an LED. Here we have a red one, but you can get them in different colours as well. We can also have something like a little speaker that allows us to convert digital data into sound or a buzzing. We can also use a full-fledged screen.
So if you want to have more complex text, or information, or like a banner that where information is moving from screen from left to right, you can use one of these. And I think a final example is this motor that we can use to create motion. So we have a little axis there that we can connect to robot arms or to other external form factors.

Let’s take a closer look at transduction devices.

In this presentation, Dr Steven Houben explains how the devices use real world energies to transform digital information into physical phenomena in the real world. He will show you up-close examples of these sensors and actuators at work.

Over to you:

Think about the physical computing device that you chose in the previous step.
What role do the output transducers, or actuators, play in your device?
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Introduction to Physical Computing

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