[Aleksei]

Instead of G=1/s+1 use G=fotf(1/s+1).

[Aleksei]

Please post the specific text of the error.

[Aleksei]

It is included, but not supported in MATLAB R2010a.
Please see this comment: https://fomcon.net/fomcon-toolbox/download/#comment-1919

[Aleksei]

I assume that you are using FOMCON.
Check whether the FOD library is on MATLAB path.
Also, which version of MATLAB are you using?

[Aleksei]

Please provide a particular example and/or screenshot. Which GUI are you referring to?

[Aleksei]

It is likely that this is not a bug. For some systems the integral may indeed not converge. So, the result of computation of the norm depends on the system under investigation.

[Aleksei]

This is a bug. Consider the following patch: https://fomcon.net/forums/topic/preliminary-releases-and-patches/#post-1037
Towards your second request, see the following PDF: http://www.abo.fi/~htoivone/courses/robust/rob2.pdf

[Aleksei]

This patch addresses the problem with the norm() function for the fotf object: 0.41-beta-patch-2015_01_09.zip
Put the folder inside the patch into the FOMCON root directory and overwrite the affected file.

• This reply was modified 11 years, 10 months ago by Aleksei.

[Aleksei]

You may use stepinfo() on an approximated system. This function is not yet available for fotf systems.

[Aleksei]

E.g., using the Oustaloup approximation method.

• This reply was modified 11 years, 11 months ago by Aleksei.

[Aleksei]

CRONE has several generations of controllers. Kindly see the book in https://fomcon.net/fo/overview-of-literature/ for details.

For instance, the first generation CRONE controller has the following form
\[
C(s)=C_0 s^{\alpha}\tag{1},
\]
with $\alpha, C_0\in\mathbb{R}$. This can be seen as one of the dynamical components of a fractional-order PID controller, e.g., the integral component
\[
C_I(s)=K_i s^{-\lambda},
\]
where $C_0=K_i$ and $\alpha=-\lambda$ in (1).

• This reply was modified 11 years, 11 months ago by Aleksei.
• This reply was modified 11 years, 11 months ago by Aleksei.
• This reply was modified 11 years, 11 months ago by Aleksei.
• This reply was modified 11 years, 11 months ago by Aleksei.

[Aleksei]

There is no optapp function in FOMCON.

[Aleksei]

I have answered this question in the comments on the main site.

[Aleksei]

The function is named oustafod, not ousta_fod.

[Aleksei]

At some point I discovered an issue in FOMCON code related to classical PID controller tuning.

What I am currently getting is this. With $K=0.588205$, $L=67.379$, and $T=5054.34$ the tuning is $K_p=153.036$, $K_i=1.13563$, and $K_d=5155.69$.

• This reply was modified 12 years ago by Aleksei.

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