PID CONTROLLER

Presented By (Group 5)

SINTU KUMAR SHARMA

0017 AVISHEK MUKHERJEE

0018 MD ASHRAF ALAM KHAN

0019 DALI DAS

0020

HISTORY BEHIND PID CONTROLLER

• At first PID controller was used in automatic ship steering in 1890 by Elmer Sperry

•Its theory was published in 1922 by Russian American engineer Nicolas Minorsky .

what is a Controller?

A controller is a device that generates an output signal based on the input signal it receives.

The input signal is actually an error signal, which is the difference between the measured variable and the desired value

Fundamental Controller

Introduction

PID stands for Proportional (P), Integral (I), Derivative (D) controller.

BASIC BLOCK DIAGRAM OF PID CONTROLLER

Proportional term

The proportional term produces an output value that is proportional to the current error value. The proportional response can be adjusted by multiplying the error by a constant Kp, called the proportional gain constant.

The proportional term is given by:

Integral term

The contribution from the integral term is proportional to both the magnitude of the error and the duration of the error. The integral in a PID controller is the sum of the instantaneous error over time and gives the accumulated offset that should have been corrected previously. The accumulated error is then multiplied by the integral gain and added to the controller output.

The integral term is given by:

Derivative term

The derivative of the process error is calculated by determining the slope of the error over time and multiplying this rate of change by the derivative gain Kd. The magnitude of the contribution of the derivative term to the overall control action is termed the derivative gain, Kd.

The derivative term is given by:

How to Designing a PID Controller And Why

1. Obtain an open-loop response and determine what needs to be improved .

2. Add a proportional control to improve the rise time.

3. Add a derivative control to improve the overshoot .

4. Add an integral control to eliminate the steady-state error .

5. Adjust each of Kp, Ki, and Kd until you obtain a desired overall response.

TERMS USED:-

CL RESPONSE

RISE TIME OVERSHOOTSETTLING

TIMES-S ERROR

Kp Decrease Increase Small Change Decrease

Ki Decrease Increase Increase Eliminate

KdSmall

ChangeDecrease Decrease

Small Change

The Characteristics of P, I and D controllers

The PID control scheme is named after its three correcting terms, whose sum constitutes the manipulated variable (MV). The final form of the PID algorithm is:

where

PID controller theory

Plot of PV vs. time, for three values of Kp ( Ki and Kd held constant)

Graphical Analysis

Plot of PV vs time, for three values of Ki (Kp and

Kd held constant)

Plot of PV vs time, for three values of Kd (Kp and Ki held constant)

Applications of PID PID controllers are

applicable to many control problems, and often perform satisfactorily without any improvements or even tuning.

It is used widely in the process industry, automation system, process dynamics and in particular the loop dead time.

PID Controller Design for a DC Motor

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