**PID control** stands for a **proportional–integral–derivative control**. PID control is a feedback mechanism used in a

The Laplace transform of the actuating signal incorporating PID control is

There are some control actions which can be achieved by using any of the two parameters of the **PID controller**. Two parameters can work while keeping the third one to zero. So PID controller becomes sometimes PI (proportion-integral), PD (proportional-derivative) or even P or I. The derivative term D is responsible for noise measurement while the integral term is meant for reaching the targeted value of the system. In early days PID controller was used as a mechanical device. These were pneumatic controllers as they were compressed by air. Mechanical controllers include spring, lever or mass. Many complex electronic systems are provided with a PID control loop. In modern days PID controllers are used in PLC (programmable logic controllers) in the industry. The proportional, derivative and integral parameters can be expressed as – K_{p}, K_{d} and K_{i}. All these three parameters have an effect on the closed loop control system. It affects rise time, settling time and overshoot and also the steady state error.

Control Response | Rise time | Settling time | Overshoot | Steady state error |

K_{p} | decrease | small change | increase | decrease |

K_{d} | small change | decrease | decrease | no change |

K_{i} | decrease | increase | increase | eliminate |

**PID control** combines the

Proportional Control: Here actuating signal for the control action in a control system is proportional to the error signal. The error signal being the difference between the reference input signal and the feedback signal obtained from input.

Derivative Control: The actuating signal consists of proportional error signal added with derivative of the error signal. Therefore, the actuating signal for derivative control action is given by,

Integral Control: For integral control action the actuating signal consists of proportional error signal added with integral of the error signal. Therefore, the actuating signal for integral control action is given

A **PID controller** has some limitations also apart from being one of the best controllers in