Norman.Nise - Control.Systems.Engineering.6th.Edition

A control system is a device, or set of devices to manage, command, direct or regulate the behavior of other device(s) or system(s). Industrial control systems are used in industrial production.
There are two common classes of control systems, with many variations and combinations: logic or sequential controls, and feedback or linear controls. There is also fuzzy logic, which attempts to combine some of the design simplicity of logic with the utility of linear control. Some devices or systems are inherently not controllable.

Norman.Nise - Control.Systems.Engineering.6th.Edition.pdf