SYSTEM IDENTIFICATION AND PID DESIGN
for
MR. ADRIAN LUTCHMAN
Professor, Process Control
The University of Trinidad and Tobago,
Point Lisas Campus
From
NAME
ID NUMBER
NAKEYAH COLLINS
77258
Department of Process Engineering
Full Time
Point Lisas Campus
Submission date: November 30th, 2020
Contents
1.0
Problem Statement .......................................................................................................... 3
2.0
Results ............................................................................................................................. 4
3.0
Discussion ....................................................................................................................... 9
1.0 Problem Statement
You have been provided with data from an open loop step test to a process. You are required
to fit a First Order Plus Dead-time (FOPDT) model to the data and design a PI or PID
controller to control the process. You are then required to model and test the controller’s
response to both set-point changes as well as disturbances. You must then write a small
discussion on your controller’s performance.
Figure 1: Assignment data sheet
2.0 Results
Figure 2: Simulink Model
Figure 3: IMC tuning parameter of 19 with no disturbance added
Figure 4: IMC tuning parameter of 19 with disturbance added
Figure 5: IMC tuning parameter of 100 with no disturbance added
Figure 6: IMC tuning parameter of 100 with disturbance added
An IMC parameter of 100
Figure 7: IMC tuning parameter of 120 with no disturbance added
Figure 8: IMC tuning parameter of 120 with no disturbance added
Figure 9: IMC tuning parameter of 115 with no disturbance added
Figure 10: IMC tuning parameter of 1 with no disturbance added
3.0 Discussion
The PID controller combines proportional control with additional integral and derivative
adjustments, helping the unit to automatically compensate for changes in a system. As a
feedback controller, the PID controller’s core purpose is to force feedback to match a
setpoint.
The tuning parameter IMC was altered on the FOPDT Model spreadsheet (attached) to
achieve different PID values. After running solver and attaining the best fit, we see that our
tuning rule parameters gave us a lower boundary of 16.34542975 and a higher boundary of
22.57571626. For the first run the IMC tuning parameter was set to the average boundary
value of approximately 19. Using an IMC parameter of 19 does not give us a smooth system
therefore we continue changing the value.
As seen from the figures above, the IMC parameter is constantly adjusted to get a stable
process. For example, when the IMC parameter was set to a value of 100, we can see our
system starting to stabilize however it becomes a bit underdamped at around 70 seconds.
When we add a disturbance to the system we notice that the process was getting to the set
point but suddenly overshoots. However, we observe that the controller quickly tries to
rectify this offset and brings the process back to the setpoint of 54.