03-13-2007 11:57 AM - edited 03-13-2007 11:57 AM
In the PID toolset
the example
General Auto PID Simulator.vi there is a file called Plant
Simulator.vi
I could not get or construct the transfer function of
the plant from the data given to this file.
The input Variables to
this file as follow:
iteration, Manipulated variable (output, %), Initial PV, dt (s), Process Gain, Process Load, Lag (min), Valve Deadband, Process Deadtime, Controller Noise (%), Measurement Noise (%).
The output Variable is
Process Variable (%).
The File use PID Lead-Lag File to give the output variable.
For example if I want the plant transfer function P(s)= (Kp * e^(t*s)) / (Tp*s)
where Kp is process gain, t deadtime, Tp is the Time constant.
Kp=2 , t= -3, Tp= 10.
what input should I give to Plant
Simulator.vi to implement my process?
any help
thanks
Message Edited by mksa on 03-13-2007 12:04 PM
03-14-2007 07:44 AM
mksa,
Before you carry on using this VI, I strongly advice you to verify if you have the LabVIEW Simulation Module available in your University or Company. If you have that, you can enter this information directly using more meaningful functions as Integration, Gain and Time Delay.
If you can't really have this Module, you will have to develop your own code for this operation. The Plant Simulation don't have an Integrator and you equation has one. So, you can't use this function to simulate this operation.
If you have the previous version of the PID Control Toolset 8.2, you can use the Advanced Control VIs to simulate the integrator with gain in series with Deadband. If you have version 8.2, this is not present at the pallette, but you can find it in <labview dir>\vi.lib\addons\control\advanced\. However, as you can see in the pictures attached, Simulation Module really help to express you equation instead of Advanced Control VIs.
On a final note, I notice that you called Tp as Time Constant. If that is really the case, you equation should be "P(s)= (Kp * e^(t*s)) / (Tp*s +1)", and, in this case, you COULD simulate with the plant. Let me know if that is the case and I can tell you what parameters to enter.
Barp - Control and Simulation Group - LabVIEW R&D - National Instruments
03-22-2007 12:54 PM
if Tp is note the Time Constant what
would it will be called? and I want to simulate the same equation
which in this article.
Rongfu Luo, Joe Qin, Dapang Chen. "A
New Approach to Closed Loop Autotuning for PID Controllers";
Proceedings of the American Control Conference; Philadelphia,
Pennsylvania; June 1998.
which as i post.
03-23-2007 08:25 AM
04-02-2007 02:07 AM
04-02-2007 07:28 AM
The VIs names are:
For Advanced Control VIs (available on the PID Control Toolset version before 8.2): "Integrator.vi" and "transport delay.vi"
For the Simulation Module: Transfer Function and Transport Delay. They are Simulation Nodes.
Hope this help!
04-02-2007 09:27 AM
04-03-2007 12:50 AM
I want to simulate a DC Motor model, so I thought of doing a cascade files Plant Simulator
the transfer function for speed DC Motor is
I thought that it might be possible to implement the equation
K/(Js+b) in Plant Simulator but i don't know how to multiply s by J in Plant Simulator file.
Then multiply the previous result with the result of 1/(Ls+R) Plant Simulator file
then add the previous result to K/K2
Dose any one think this method will work out the DC Motor simulation.
04-03-2007 08:42 AM
mksa,
The Simulation Module is an addon module to LabVIEW that allow to do all the operations that you'd like to do. You can easily mix LabVIEW Code with Simulation nodes and create the block diagram necessary for simulation.
To obtain this Module, there is an additional purchase nessary. If you are an student, there is a very good chance that your university have this module available for your use. If not, the student version of LabVIEW have the Simulation Module available. Try to contact the sales representative from your area to know what the best way to obtain the Module:
http://sine.ni.com/apps/utf8/nicc.call_me
Hope this help!