PID is a three-letter acronym that stands for Proportional–Integral–Derivative controllers. PID controllers or three-term controllers are control loop feedback (mechanism) controllers widely used in industrial control systems and various applications requiring continuously modulated control. HISTORY The PID controller is the most common form of feedback control. In 1911, the businessman and inventor Elmer Sperry created the PID control which combines these three actions. PID controllers were first used in the 1930s to control manufacturing processes. PID controllers were first used in the control of steam engines. The PID controller has been used in a variety of industries since its inception. PID controllers were first used in the 1950s in the control of nuclear power plants. Each of those three words represents one of the three main components of a PID controller. PID controllers are used in all sorts of machines that need to be controlled, such as robots and c...