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Re: [python-control-discuss] [BULK] MIMO vs SISO
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From: Sawyer F. <mi...@ca...> - 2011-04-07 18:11:19
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What Ryan and Richard have suggested seem like pretty good solutions to me: maybe a property of the system that defaults to being SISO if the system has only input and one output (but can be set to MIMO if desired), and a way to override that setting in the calling function? Sawyer ------------------------ Sawyer B. Fuller Ph.D. Candidate, Bioengineering California Institute of Technology http://www.cds.caltech.edu/~minster/ <http://alumni.media.mit.edu/~minster/> On Thu, Apr 7, 2011 at 10:18 AM, Ryan Krauss <rk...@si...> wrote: > I think the idea of having toSISO be a property of the system makes a > lot of sense. At worst, I would have to override it once for each > system that I analyze. We could allow it to be overwritten in the > function calls if we wanted to, but default to the instance property > if it is not passed in: > > def bode(self, ...., toSISO=None): > if toSISO is None: > toSISO = self.toSISO > > Just my thoughts. > > Ryan > > > > On Thu, Apr 7, 2011 at 11:47 AM, Steve Brunton <sbr...@pr...> > wrote: > > Hi All, > > > > This idea of having keywords to change the output format is what we had > in mind when extending to MIMO (as well as whether to plot or just return > output for a command like 'bode'). A a nice interface might have a SISO > system default toSISO=True, a MIMO system would default toMIMO=True, and > there would be the option to have a SISO system output as a MIMO system (for > example if you have scripts that work on both SISO and MIMO outputs). > > > > Even Matlab doesn't have this completely sorted out. When I do > [m,p,w]=bode(sys,w), I still have to squeeze the output for a SISO system. > > > > -S,L,K,B > > > > > > On Apr 7, 2011, at 11:15 AM, Ryan Krauss wrote: > > > >> I think this essentially makes sense, but I use the toolbox with my > >> undergrads who are new to python. They might find it annoying to have > >> to pass in the extra keyword argument toSISO=True every time they > >> generate a Bode plot or something. Can we try to intelligently guess > >> what toSISO should be in the code? i.e. if the system has only one > >> input and one output, assume toSISO=True. We may be able to make this > >> work by using numpy.squeeze on all array outputs. > >> > >> Ryan > >> > >> -- > >> Ryan Krauss, Ph.D. > >> Assistant Professor > >> Mechanical Engineering > >> Southern Illinois University Edwardsville > >> > >> > >> > >> On Thu, Apr 7, 2011 at 9:56 AM, Richard Murray <mu...@cd...> > wrote: > >>> I noticed this change as well. If you are just using the various > functions in python-control, everything works fine (eg, none of the examples > had to change). But if you are extracting frequency responses or otherwise > playing with data generated from your system, this is a bit of a hassle. > >>> > >>> Here is a proposal: > >>> > >>> * For all functions in python-control that accept MIMO systems (all of > them eventually), we add two keywords: > >>> > >>> - toSISO=True will force output to be SISO-like (v0.3) if inputs==1, > outputs==1 > >>> - toSISO=(n, m) will give you SISO-like output for the nth input to > mth output > >>> - toMIMO=True will force the output to be MIMO-like even if inputs==1, > outputs==1 > >>> > >>> * For the Python interface, the default will be toMIMO=True, so that > you get the current behavior. If you want the scalar version of the > outputs, you just add toSISO=True as a keyword. > >>> > >>> * For the MATLAB interface, the default will toSISO=True, so that you > get MATLAB-like behavior if you extract data from bode(), freqresp(), etc. > >>> > >>> One problem with this is that you can have conflicts if you give *both* > sets of keywords. Sometimes this makes sense ("toSISO=(2,3) toMIMO=True"), > but sometimes it doesn't ("toSISO=True, toMIMO=True"). So probably needs a > bit more thought. But the idea is that the following code: > >>> > >>> (mag, phase, omega) = bode(sys) > >>> plot(omega[0][0]), mag[0][0]) > >>> > >>> becomes > >>> > >>> (mag, phase, omega) = bode(sys, toSISO=True) > >>> plot(omega, mag) > >>> > >>> which I think is a bit cleaner. > >>> > >>> Comments, suggestions? > >>> > >>> -richard > >>> > >>> > >>> > >>> On 6 Apr 2011, at 14:19 , Sawyer Fuller wrote: > >>> > >>>> Hey i just downloaded the latest version of python-control and it > looks like everything has gone MIMO. Pretty cool, but is there any way to > way to stick to SISO, eg a subclass or flag? A little bit of a drag to > constantly be appending [0][0] to every frequency response for the most > common use case. I think matlab does a special-case for SISO. Anything like > that in the works or somewhere i'm not finding it? > >>>> > >>>> S > >>>> > >>>> > >>>> ------------------------ > >>>> Sawyer B. Fuller > >>>> Ph.D. Candidate, Bioengineering > >>>> California Institute of Technology > >>>> http://www.cds.caltech.edu/~minster/ > >>>> > >>>> > >>>> > ------------------------------------------------------------------------------ > >>>> Xperia(TM) PLAY > >>>> It's a major breakthrough. An authentic gaming > >>>> smartphone on the nation's most reliable network. > >>>> And it wants your games. > >>>> > http://p.sf.net/sfu/verizon-sfdev_______________________________________________ > >>>> python-control-discuss mailing list > >>>> pyt...@li... > >>>> https://lists.sourceforge.net/lists/listinfo/python-control-discuss > >>> > >>> > >>> > ------------------------------------------------------------------------------ > >>> Xperia(TM) PLAY > >>> It's a major breakthrough. An authentic gaming > >>> smartphone on the nation's most reliable network. > >>> And it wants your games. > >>> http://p.sf.net/sfu/verizon-sfdev > >>> _______________________________________________ > >>> python-control-discuss mailing list > >>> pyt...@li... > >>> https://lists.sourceforge.net/lists/listinfo/python-control-discuss > >>> > >> > >> > ------------------------------------------------------------------------------ > >> Xperia(TM) PLAY > >> It's a major breakthrough. An authentic gaming > >> smartphone on the nation's most reliable network. > >> And it wants your games. > >> http://p.sf.net/sfu/verizon-sfdev > >> _______________________________________________ > >> python-control-discuss mailing list > >> pyt...@li... > >> https://lists.sourceforge.net/lists/listinfo/python-control-discuss > > > > > > > ------------------------------------------------------------------------------ > > Xperia(TM) PLAY > > It's a major breakthrough. An authentic gaming > > smartphone on the nation's most reliable network. > > And it wants your games. > > http://p.sf.net/sfu/verizon-sfdev > > _______________________________________________ > > python-control-discuss mailing list > > pyt...@li... > > https://lists.sourceforge.net/lists/listinfo/python-control-discuss > > > > > ------------------------------------------------------------------------------ > Xperia(TM) PLAY > It's a major breakthrough. An authentic gaming > smartphone on the nation's most reliable network. > And it wants your games. > http://p.sf.net/sfu/verizon-sfdev > _______________________________________________ > python-control-discuss mailing list > pyt...@li... > https://lists.sourceforge.net/lists/listinfo/python-control-discuss > > |
