1. Control engineering and signal processing
PID controller
Control engineering and signal processing
Michala Srnová
2009/2010

2. Content Compensator P compensator PI compensator Lead compensator
Lag compensator
PID controller

3. PID controller Proportional + integral + derivative Transfer function:
KD – derivative gain
Used in majority of closed-loop industrial processes

4. PID controller Step response Effect of increasing the parameters:
Rise time
Overshoot
Settling Time
Steady state Error
Effect of increasing the parameters:

5. Tune Alter step response Find out parameter Kp, Ki, Kd Various methods
Manual Tuning
Ziegler-Nichols
Software Tools
Cohen-Coon

6. Manual Tuning No math required On-line method
What in characteristic need to be improved
Kp – decrease the rise time
Kd – reduce overshoot and settling time
Ki – eliminate steady state error
Does not work in every time

7. Ziegler-Nichols Rules for determine Kp, Ki, Kd Based on step response
Proposed more methods
First method – Step response method
No integrators
No dominant
complex-pairs
Response:
s-shape, no overshoot
Ʈ, a
In the graph
Tangent line in the inflection point
The crossing of x axis : L
Crossing of steady state level → L2 T=L2-L

8. Ziegler-Nichols Parameters Ʈ and a – calculating
Drawbacks: lack robustness
Improvement : K, Ʈ, T in model
From step response

9. Ziegler Nichols Second method – frequency response
Ki and Kd =0, setting of Kp
Starting of ocsillations → Kc, period – Tc
These values used to calculate Kp,Ki,Kd

10. Software Tuning Modern industrial facilities Online, offline method
Software will
Gather data
Develop process model
Suggest optimal tuning
Principle
Mathematical loops
Frequency response to impulse
Design PID loop values

12. Thank you for your attention