Basic concepts of control systems

A control system means any interesting or variable quantity in a machine, mechanism or other device that can be maintained and changed in a desired manner. The control system is also implemented to make the controlled object reach a predetermined ideal state. The control system makes the controlled object tend to a certain required stable state.
For example, suppose there is a car drive system, and the speed of the car is a function of its accelerator position. By controlling the pressure of the accelerator pedal, the desired speed can be maintained (or the desired speed change can be achieved). This car drive system (accelerator, carburetor and engine vehicle) constitutes a control system.