Control : Embedded Systems

Control : Embedded Systems

Many computerised control systems are built into other devices that we use on a daily basis in the home and whilst travelling. A computer that is built into another machine is known as an embedded control system. Embedded systems have replaced mechanical or manual control of devices and enabled new sophisticated machines to be produced.

Here are some example of machines that commonly contain embedded systems :

Machine	Use of Embedded System
Burglar Alarms	Burglar alarms usually incorporate an embedded system that uses sensors to detect the presence of an intruder. The system will be able to activate devices such as an alarm bell and telephone dialler if a break-in occurs. It may also be able to keep a log of events and communciate with a remote central monitoring station.
Environmental Control	Heating and air conditioning systems in homes, offices, cars and greenhouses use temperature sensors to measure the temperature of the area they control. They can turn on devices including heaters and air conditioning units and open vents to keep the temperature within a specified range.
VCR	Video cassette recorders (VCRs) are controlled by embedded systems. The embedded system in a VCR will allow it to be programmed to turn on and off at specified times to record programs when the owner is absent.
Refrigerator	The embedded system in a refrigerator will use a temperature sensor to measure the temperature inside the fridge and turn on a cooling unit if the temperature becomes too warm to keep food safely,
Car	A modern car will incorporate many embedded systems to control various aspects of of its use. Some tasks that a car will use an embedded system for are : Access Control/Alarm : A remote control can be used to lock and alarm a car when it is parked. Anti-Lock Braking (ABS) : Computerised anti-lock braking systems allow cars to stop in shorter distances and be steered without skidding during breaking. Engine Control Unit : The engine control unit will determine the spark timing and amount of fuel to inject into the engine to obtain the best balance of performance, economy and environmental efficiency.

Using embedded systems instead of manual or mechanical control mechanisms is generally preferred because :

Embedded systems can respond more quickly than mechanical devices or humans can.
Unlike a human embedded systems can work continuosly without getting tired or making mistakes.
Embedded systems can have much more sophisticated features than equivalent manual systems.

GCSE ICT Companion 04 - (C) P Meakin 2004