Further Examples in Open Loop Tuning
Pre-Experimental Questions
Below are some questions to think about while you are running the
various processes. The answers will be given once the simulation has
been run.
- Look at the open loop response and determine:
- The steady state process gain?
- The delay time?
- The time constant?
- What are the corresponding values of the controller gain and reset
time for a PI controller using the ZN tuning method?
- Try running the process with the ZN parameters. Comment on how you
can obtain a better response.
- Now take time to investigate the response with control using very
large and very small values of controller gain and reset time.
Run Simulation
It is now possible to choose the required process in the form below and
run the simulation. Initially the relevent process will be run with no
control. When the button is clicked the open loop response will appear
given a unit increase in the input.
Once this has been analysed different gains and/or
integral times can be tried until an understanding of these two
parameters is gained.
- To choose the type of process simply click on the button beside the short
description.
- To choose a gain click in the relevent box and change the value.
- To choose an integral reset time click in the relevent box and
change the value.
- Note that the setpoint value is always 0.
Once you are happy with the inserted values, click on the Enter
Values button and wait for the computer to generate the results
and produce a graph. It is possible to run the experiment as many times
as necessary until you think you understand the process and can answer
the above questions.