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

1. PID CONTROLLER
Presented By
 Anzar Ali
 PH 14006

2. 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

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

4. 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:

5. 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:

6. 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:

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

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

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

10. The tuning parameters essentially determine:
How much correction should be made? The magnitude of
the correction (change in controller output) is determined by
the proportional mode of the controller.
How long the correction should be applied? The duration
of the adjustment to the controller output is determined by
the integral mode of the controller
How fast should the correction be applied? The speed at
which a correction is made is determined by the derivative
mode of the controller.

11. 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.

12. PID controller theory
 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
Plot of PV vs. time, for three values of Kp (
Ki and Kd held constant)

13. 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