## Forum Replies Created

Viewing 7 posts - 61 through 67 (of 67 total)
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• in reply to: Forum announcements #763
Aleksei
Keymaster

Due to an unprecedented abundance of automated spam messages, forum posts will usually go through manual premoderation. I am sorry for the inconvenience. I am looking into the issue of efficient spam rejection, but meanwhile the publication of your messages may be delayed.

in reply to: Fractional PID Controller Design #761
Aleksei
Keymaster

Hi,
No, there is no overloading function stepinfo() for the fractional-order transfer function object yet, but the CST version can be employed as well. Consider an example:

loadsets
[y,t]=step(oustapp(G2));
stepinfo(y,t,1)


Here, I first load the example systems provided with FOMCON, then approximate a fractional-order system G2 by an integer-order one in the form of a refined Oustaloup recursive filter and obtain y and t vectors explicitly.

Note, however, that approximation parameters for a particular system need to be thoroughly selected to obtain a feasible result.

in reply to: Toolbox features #574
Aleksei
Keymaster

You may estimate the fractional-order transfer function by first creating a fidata() data structure from your y, u, and t vectors, containing output, input, and time instance values, respectively. Next, you could use either the graphical interface fotfid (more convenient) or the fid() function.

It should also be possible, depending on the input/output time series data, to arrive at the frequency-domain representation of the system characteristics, but at the moment there are no tools in FOMCON that would do the conversion for you.

in reply to: Toolbox features #522
Aleksei
Keymaster

At this point, the static gain cannot be explicitly set in the model structure.

in reply to: Toolbox features #520
Aleksei
Keymaster

Hello,

Thank you for contacting the FOMCON support forum! You may supply the FOTF object as
fotf('s^alpha','s^alpha+p')
However, both parameters alpha and p must have particular numerical values. The general structure of the model will be retained.

in reply to: Fractional PID Controller Design #516
Aleksei
Keymaster

Hello, and thank you for your feedback!

1. In order to run the optimization procedure, the plant does not need to be stable per se; however, you will most likely run into problems with unstable plants. Careful initial inspection of unstable systems is advised.

2. Please check that your path is correctly set. Which version of MATLAB are you using? There is a backwards compatibility issue that appeared somewhere between R2010 and R2012 which is related to particular class methods and overloading thereof. This issue may need to be reported via the bug tracker.

3. Yes, there are several upcoming conference papers illustrating the use of the toolbox. Unfortunately, I cannot publish these on the site. I am, however, planning on creating several tutorials covering some basics of using the toolbox. A complete user manual is also planned.

in reply to: Preliminary releases and patches #512
Aleksei
Keymaster

Here is a patch for an issue with simulation/optimization of fractional-order systems with input-output delays reported here. Download: 0.3-alpha-patch-2013-03-05.zip

Put the folders inside the patch into the fomcon root directory and overwrite the two affected files.

Viewing 7 posts - 61 through 67 (of 67 total)