An actuator (アクチュエーター) is the umbrella term for output-side devices that take a control signal from a computer and turn it into physical motion, such as rotating or extending and retracting.
Sensor measures the state
Computer decides
Signal sent to the actuator
Valve or door actually moves
The actuator physically moves something, for example by opening a water valve.
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A sensor (センサー) on the input side measures physical quantities such as temperature or brightness and turns them into electrical signals, while an actuator sits at the end of the signal flow and moves real objects. In an IoT system, it handles the part that does the work on site, for example opening and closing a sprinkler valve based on a reading.
AnalogyIf sensors are the eyes and ears, actuators are the hands and feet that actually move on the brain's orders.
How to rememberThe word is built on act (to move or do), so read it as "the thing that makes something act."
Exam points
ExamAn actuator (アクチュエーター) follows instructions sent from a server (サーバ) or similar and does the job of physically moving things on site.
Mix-upA sensor (センサー) is on the input side, measuring physical quantities and turning them into electrical signals, while an actuator (アクチュエーター) is on the output side, turning signals into motion; the signal runs in opposite directions.
A DC motor (DCモーター) is a motor whose shaft rotates when direct current flows through it, and it is a typical example of an electrically driven actuator.
Raising or lowering the applied voltage changes the speed, and reversing the current makes it spin the other way. Because it can even run on batteries, it is widely used in models, small home appliances, robot joints, and the like.
AnalogyIt is like the heart of a toy car, which starts spinning as soon as you hook up a battery.
How to rememberDC stands for Direct Current, while the alternating current from a household outlet is written AC (Alternating Current).
A hydraulic cylinder (油圧シリンダ) is an actuator that pushes a piston with the pressure of oil fed into a tube, producing linear motion.
Oil barely compresses, so even a small unit can deliver great force and hold a chosen position accurately. It is used, for example, in the arms of construction machinery that lift heavy loads and in press machines.
AnalogyIt works like pushing a syringe plunger with liquid: the plunger drives straight ahead with great force.
How to rememberThe Japanese name 油圧 combines "oil" and "pressure," telling you exactly what does the pushing; the English "hydraulic" likewise points to liquid.
A pneumatic cylinder (空気圧シリンダ) is an actuator that pushes a piston with the force of compressed air, producing linear motion.
Air is light and flows easily, so it suits quick back-and-forth motion, and a leak hardly dirties the surroundings. On the other hand, air compresses, so the force and positioning accuracy fall short of the oil-based type.
AnalogyLike blowing into a straw so the paper wad inside shoots out, it uses air pressure to push something out quickly.
Exam points
Mix-upA hydraulic cylinder (油圧シリンダ) uses hard-to-compress oil to deliver strong force, while a pneumatic cylinder (空気圧シリンダ) moves lightly and quickly on compressed air. Both produce linear motion.
A device driver (デバイスドライバ) is software that acts as a go-between for the OS or applications and a peripheral device, translating commands bound for that device into a form the device understands and operating it.
Application
OS
Device driver
Peripheral device
Each device accepts commands differently, so drivers are built for a specific device type or model, and most are supplied by the manufacturer. Applications ask the driver to do the work through the OS, so they can print or scan without worrying about the fine differences between devices.
AnalogyIt is like a dedicated interpreter who comes along when you operate a foreign machine, with a different interpreter for each machine.
How to rememberA driver is "one who operates," so, like the driver of a car, it is the one that operates the device.
Exam points
ExamA device driver (デバイスドライバ) is software that controls a peripheral device, and it is needed when an application uses a connected device too.
ExamA driver installed later, separately from the OS, does not come back when the OS is reinstalled. After you initialize the disk and reinstall the OS, you have to reinstall the driver as well.
Plug and Play (プラグアンドプレイ) is a mechanism in which, once you connect a peripheral device, the OS automatically recognizes it and takes care of installing and configuring the matching device driver.
Connect the device
OS recognizes the device
Driver installed and configured
Ready to use right away
The device becomes usable without the user setting anything up by hand.
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It exists to save you the trouble of finding and installing drivers by hand, and connection standards such as USB support it. Connecting or removing a device while the power stays on is called hot plugging (ホットプラグ), a feature concerned with when you may attach or detach.
AnalogyIt is like a thoughtful front desk where staff size up your preferences the moment you walk in and set up your seat and tools for you.
How to rememberPlug (insert) plus play (use) reads as "plug it in and use it right away."
Exam points
ExamWhat Plug and Play (プラグアンドプレイ) does automatically is install into the OS a device driver (デバイスドライバ) that fits the newly connected device, and configure it.
Mix-upHot plugging (ホットプラグ) lets you attach and detach devices with the power on, while Plug and Play (プラグアンドプレイ) automates recognition and setup after connection; they cover different moments.