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changing a parameter inside a continuous transfer function during simulation

Asked by Danilo NASCIMENTO on 16 Aug 2015
Latest activity Commented on by Sebastian Castro on 17 Aug 2015
Hey guys, I want to change a parameter of a continuous transfer function during a simulation. Is that possible?


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1 Answer

Answer by Sebastian Castro on 17 Aug 2015

Yes, it is possible.
You can go right into the block and change the parameters mid-simulation. When you hit "OK" in the block, the parameters update.
If you want to do this programmatically, you can do the following -- suppose you are changing a parameter K in a model called myModel:
>> K = 0.2;
>> set_param('myModel','SimulationCommand','update');
- Sebastian


Well, it can be useful. But this is not what I mean. I don't want to change it manually. For instance, let's suppose I have a continuous transfer function called G(s)=1/(s^2+w0^2), I want to change the parameter w0 at time 0.4 s with a command. This is all in simulink.
I just tried this out by putting the above MATLAB commands inside a MATLAB Function block. Notice a few subtle changes like declaring some functions extrinsic (due to code generation), and also assigning values in the MATLAB base workspace with assignin (a necessary "evil" in this case).
This is then placed inside a Triggered Subsystem that triggers when the simulation time exceeds a certain value. For example:
Notice that I am changing the frequency w0 from 1 to 5 at a time of 4 seconds. My results change as follows:
- Sebastian

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