Systems and Control

What is a System? A system is a set of devices or things which are connected and work in conjunction with each other in order to perform a specific function.

All systems have PROCESS INPUT OUTPUT

Example:

PROCESS INPUT OUTPUT

A system is sometimes made of subsystems joined together. INPUT Door sensor Burglar Alarm INPUT Window sensor PROCESS OUTPUT Siren Flashing light INPUT Panic button

INPUT Input sensors usually convert a change in light, movement, temperature or humidity into changes in electrical signals. The inputs are often tiny changes of voltage, current or resistance.

PROCESS The process or processor is the part of a control system which reacts to the inputs. The changes to the inputs are usually too small to operate output devices like buzzers or motors, so they have to be amplified to give a large enough change to operate the output devices.

Processing Device Example Amplifiers Amplifies small inputs Electronic switches Switches at different levels Timers Switches after time delay Counters Counts input pulses Computers Detects signals from inputs Micro-processors

OUTPUT Output devices are those which convert electrical signals into sound, light or movement. Output Device Example Lamps Light Buzzers/Bells Sound Speakers Motors Movement Indicators Information