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Re: MIMO models in Control 2.0.0
From: |
Lukas Reichlin |
Subject: |
Re: MIMO models in Control 2.0.0 |
Date: |
Mon, 21 Mar 2011 17:38:16 +0100 |
On 21.03.2011, at 13:58, Richard Balogh wrote:
> Hello,
>
> if I understand it well, it is not yet possible to construct MIMO models in
> Control 2.0.0 package.
> Or is there a way how to model the step response of the DC motor with two
> inputs (voltage, load) and one output (omega)?
>
> I need to model it and to inspect its responses - see also attached figure.
> Any advices, please?
>
> http://octave.1599824.n4.nabble.com/file/n3393485/SimulinkDCM.png
>
>
> Richard Balogh
Hi Richard,
MIMO models are possible both in state-space as well as in transfer functions.
However, there are some issues with tf models:
The time responses are computed in state-space. Therefore, tf models are
converted internally to state-space first. Since the tf2ss routine (taken from
control-1.0.11) is not capable to convert MIMO models, you will get an error
message for MIMO tf models in combination with time response commands.
Frequency responses are *not* affected at all.
Because of the same "old" tf2ss routine, tf model interconnections are limited
to SISO models. If you're interested in details, have a look at the file
@tf/__sys_connect__.m, you get the path by "which tf".
Most of the existing conversion routines from SLICOT are limited to proper
models. I need routines which are able to convert non-proper (more zeros than
poles) transfer functions to descriptor state-space models and back. Today I
don't understand its theory. As a stopover, I'll use the SLICOT routines in a
future release.
OK, enough of the technobabble :-) I recommend that you use state-space models
to describe MIMO systems.
Regards,
Lukas