Control : Devices

Control : Devices

Devices are used by a control system to make changes to the real world environment that the system controls. Devices are also known as actuators. The devices are activated by electrical signals sent to them by a computer.

There are lots of different devices available. Examples of common devices include :

Device	Action Produced	Application
Bulb	Lights up an area.	Lighting up a garden when a person walks into the area.
Motor	Rotation of a shaft.	Moving a buggy.
Buzzer	Makes a short beep noise.	Warning a pilot of a dangerous situation.
Pump	Moves gasses or liquids from one place to another.	Keeping a fish tank supplied with oxygen.
Heater	Produces heat.	Keeping a house warm in a central heating system.
LCD Display	Displays short sequences of numbers or letters.	Information readout on a till.

The action of many devices will depend upon how high or low the analogue voltage that is sent to the device is. For example :

A motor will rotate more quickly if it is supplied with a high voltage than if it is supplied with a low voltage.
A bulb will glow more brightly if it is supplied with a high voltage than if it is supplied with a low voltage.

The computer will use software to decide when to turn the devices on or off and to determine how high a voltage to send to a device. This decision will be based on the information that the system has gathered using its sensors.

GCSE ICT Companion 04 - (C) P Meakin 2004