[Octave-bug-tracker] [bug #40960] mixsyn (control tbox) delivers lower bandwidth controller than matlab/scilab

[anonymous]

URL:
  <http://savannah.gnu.org/bugs/?40960>

                 Summary: mixsyn (control tbox) delivers lower bandwidth
controller than matlab/scilab
                 Project: GNU Octave
            Submitted by: None
            Submitted on: Wed 18 Dec 2013 06:16:51 PM UTC
                Category: Octave Forge Package
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Incorrect Result
                  Status: None
             Assigned to: None
         Originator Name: Saul Mtakula
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 3.6.4
        Operating System: Microsoft Windows

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Details:

The code below generates an h infinity controller for the stacked problem. The
same code run on Matlab and Octave results in  controllers with lower
bandwidth from Octave. The plots for the respective sensitivity functions from
Octave and Matlab (as well as Scilab) are attached. 




clear()

g11num=[1];
g12num=[1];
g21num=[2 1];
g22num=[2];

gden=[0.2 1.2 1];


Gnum={g11num g12num; g21num g22num};
Gden={gden gden; gden gden};
 
G=tf(Gnum,Gden);


Gss=ss(G);
Gss=prescale(Gss);
A=1.e-4;
M1=1.5;
M2=1.5;
wb1=0.25;
wb2=25;



wp1num=[1/M1 wb1];
wp1den=[1 wb1*A];
wp1=tf(wp1num,wp1den);

wp2num=[1/M2 wb2];
wp2den=[1 wb2*A];
wp2=tf(wp2num,wp2den);

Wp1=blkdiag(wp1,wp1);
Wp2=blkdiag(wp1,wp2);
Wu=eye(2,2);
Wt=[]



[K1,mu]=mixsyn(Gss,Wp1,Wu,Wt);
L1=series(Gss,K1);
L1=minreal(L1);
T1=feedback(L1,eye(2,2));
S1=inv(eye(size(Gss))+L1);
S1=minreal(S1);
S1=tf(S1);
T1=minreal(T1);


[K2,mu]=mixsyn(Gss,Wp2,Wu,Wt);

L2=series(Gss,K2);
S2=inv(eye(size(Gss))+L2);
S2=sminreal(S2);
S2=tf(S2);
L2=minreal(L2);
T2=feedback(L2,eye(2,2));

T2=minreal(T2);
figure(1)
sigma(S1,S2);
grid
figure(2)
step(T1,T2)
grid



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File Attachments:


-------------------------------------------------------
Date: Wed 18 Dec 2013 06:16:51 PM UTC  Name: sensi_matlab.png  Size: 9kB   By:
None

<http://savannah.gnu.org/bugs/download.php?file_id=30036>
-------------------------------------------------------
Date: Wed 18 Dec 2013 06:16:51 PM UTC  Name: sensi_scilab.png  Size: 10kB  
By: None

<http://savannah.gnu.org/bugs/download.php?file_id=30037>
-------------------------------------------------------
Date: Wed 18 Dec 2013 06:16:51 PM UTC  Name: sensi_octave.png  Size: 35kB  
By: None

<http://savannah.gnu.org/bugs/download.php?file_id=30038>

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