Robust Control: dksyn example

Hi everybody,

currently I try to get familiar with the robust control toolbox. I tried to understand the dksyn command example:

if true
%Uncertain plant Gpert
G = tf(1,[1 -1]); 
Wu = 0.25*tf([1/2 1],[1/32 1]); 
InputUnc = ultidyn('InputUnc',[1 1]);
Gpert = G*(1+InputUnc*Wu); 
%Performance Weight
Wp = tf([1/4 0.6],[1 0.006]);
%Plant P/Pi
P = [Wp; 1 ]*[1 Gpert]; 
P2=[Wp,Wp*Gpert;
  1,Gpert];
[K,clp,bnd] = dksyn(P,1,1); 
[K2,clp2,bnd2] = dksyn(P2,1,1);
end

I don't understand, why the dksyn command is able to calculate a controller for P, but not for P2?! P and P2 are equal, are'nt they? Help is really appreciated. Thank you very much!

best regards

Martin

Answer 1

[Huajing Zhao]

Well, the ss matrices created for P and P2 are actually different in dimensions... I tested it with matlab, and it appears that P.A is 6*6 while P2.A is 3*3. For B, C, D they are also different