Peter Nachtwey
Member
I haven't put much effort into this problem because it doesn't make sense and I have got NO answer from Kolchak that make sense.
I see the diagram has changed.
There are 2 complex poles for the plant and they are very fast, way too fast for a temperature system. s usually has units of radians per second. Also, how can the poles be imaginary? Also, where does the zero come from? What is the 90*1/(20*s+1) come from? It could be to make the ambient temperature 90 degrees but an ambient temperature of 90 degrees seems high.
This temperature system has no dead time. Strange.
Keith, the dominate poleS better not be in the right half of the s plane or the system will oscillate.
I have said this before on other forums. Students shouldn't be allowed to use Matlab until they understand the basics of control theory. Otherwise they get answers and don't really know if they are right or even apply to their system.
I have asked where this plant model came from and have yet to get and answer. I can solve this problem in a few minutes but I feel it would be a waste of time getting the right solution to the wrong problem.
Here is a link to my Scilab autotune program. This can be used to compute a valid SOPDT model and gains. There are some test files and output to show how to use it.
http://deltamotion.com/peter/Scilab/AutoTune/
However, it assumes the plant is a SOPDT system. The gain is has units of temperature/%controloutput. The time constants are in minutes. Someone on LinkedIn used it and liked it so he wrote the user interface for it.
Here is an example of simulating a SOPDT plant. Notice the plant has time constants, not complex poles. It also has a dead time.
Mathcad has no built in functions for calculating gains so I wrote my own using the pole placement technique.
http://deltamotion.com/peter/Mathcad/SOPDT/Mathcad - SOPDT_HOTROD.pdf
I see the diagram has changed.
There are 2 complex poles for the plant and they are very fast, way too fast for a temperature system. s usually has units of radians per second. Also, how can the poles be imaginary? Also, where does the zero come from? What is the 90*1/(20*s+1) come from? It could be to make the ambient temperature 90 degrees but an ambient temperature of 90 degrees seems high.
This temperature system has no dead time. Strange.
Keith, the dominate poleS better not be in the right half of the s plane or the system will oscillate.
I have said this before on other forums. Students shouldn't be allowed to use Matlab until they understand the basics of control theory. Otherwise they get answers and don't really know if they are right or even apply to their system.
I have asked where this plant model came from and have yet to get and answer. I can solve this problem in a few minutes but I feel it would be a waste of time getting the right solution to the wrong problem.
Here is a link to my Scilab autotune program. This can be used to compute a valid SOPDT model and gains. There are some test files and output to show how to use it.
http://deltamotion.com/peter/Scilab/AutoTune/
However, it assumes the plant is a SOPDT system. The gain is has units of temperature/%controloutput. The time constants are in minutes. Someone on LinkedIn used it and liked it so he wrote the user interface for it.
Here is an example of simulating a SOPDT plant. Notice the plant has time constants, not complex poles. It also has a dead time.
Mathcad has no built in functions for calculating gains so I wrote my own using the pole placement technique.
http://deltamotion.com/peter/Mathcad/SOPDT/Mathcad - SOPDT_HOTROD.pdf
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