musyne.m

vTools is a toolbox for Matlab 5.3 developed within the Department of Electrical Systems and A

function [K,P,mf]=musyne(plant,no,ni,blk,mrt)

% [K,P,mf]=musyne(plant,no,ni,blk,mrt) mu synthesys using
% hinfsyne and muftbtch, K is the resulting controller,
% P the closed loop plant, and mf its mu maximum value.
% The D-K loop is stopped when the ratio between the old mu response
% and the new one is below mrt decibels, (default 3db).
% As in hinfsyne, plant is the generalized plant, no the 
% number of its measured outputs, and ni the number of its 
% control inputs, while blk is the uncertainity structure.
%
% See also hinfsyne, mu, muftbtch.

% G.Campa 14/01/97

K=[];P=[];mf=inf;
if nargin<5,mrt=3;end

%------------------------------------------------------------------------%
% first iteration

gmax=1;
[K,P,gf]=hinfsyne(plant,no,ni,0,gmax,.01,inf,1);

while isempty(K),
gmax=10*gmax;
if gmax>1e32,disp('No solution found');return,end
[K,P,gf]=hinfsyne(plant,no,ni,0,gmax,.01,inf,1);
end

[bds,dvec,sens]=mu(frsp(P,logspace(-3,3,30)),blk,'s');
[s_Dl,s_Dr]=muftbtch('first',dvec,sens,blk,no,ni,[.26*mrt/3,.1*mrt/3,0,3]);

%------------------------------------------------------------------------%
% more iterations

while 1,

gmax=1;
plant=mmult(s_Dl,plant,minv(s_Dr));

[K2,P2,gf2]=hinfsyne(plant,no,ni,0,gmax,.01,inf,1);
while isempty(K2),
gmax=10*gmax;
if gmax>1e12,K2=K;P2=P;break,end
[K2,P2,gf2]=hinfsyne(plant,no,ni,0,gmax,.01,inf,1);
end

[bds2,dvec,sens]=mu(frsp(P2,logspace(-3,3,30)),blk,'s');
[s_Dl,s_Dr]=muftbtch(s_Dl,dvec,sens,blk,no,ni,[.26*mrt/3,.1*mrt/3,0,3]);

bdrt=20*log10(max(vunpck(sel(bds,1,1))./vunpck(sel(bds2,1,1))));

if bdrt<mrt,break,end
bds=bds2;K=K2;P=P2;

end
mf=max(vunpck(sel(bds,1,1)));