1.1 Definitions: System and Control

A system is a collection of objects arranged in an orderly fashion which is goal-oriented. The system is also referred to as the plant or process. Examples of systems – industrial robot, car, power turbine, induction furnace, motor, but also human body, corporation and traffic flow. Systems differ from objects (such as tools) in that they have a certain level of complexity and a power source.

Control is used whenever some quantity, such as temperature, altitude or speed, must be made to behave in some desirable way over time. For example, control methods are used to make sure that the temperature in our homes stays within acceptable levels in both winter and summer; so that airplanes maintain desired heading, speed and altitude; and so that automobile emissions meet specifications.