% Mixed sensitivity design example for robust control course
%
% Created: 17-04-05 (Jakob Stoustrup)

G = 10*tf([1 10],[1 2 100]);
Wu = zpk(-100,-1000,5);
Wp = zpk([],-10,30); % max. value 28.972

% Additive uncertainty setup:

N1 = [
    0  Wu
    Wp Wp*G
    1  G
];
N = ss(N1,'min');
[A,B,C,D] = ssdata(N);

B1 = B(:,1);    B2 = B(:,2);
C1 = C(1:2,:);
C2 = C(3,:);
D11 = D(1:2,1); D12 = D(1:2,2);
D21 = D(3,1);   D22 = D(3,2);

tss_p = mksys(A,B1,B2,C1,C2,D11,D12,D21,D22,'tss');

% [ss_cp, ss_cl, hinfo] = hinf(tss_p); gam = 1;
[gam, ss_cp, ss_cl] = hinfopt(tss_p);

[Ak,Bk,Ck,Dk] = branch(ss_cp);
K = ss(Ak,Bk,Ck,Dk);

w = logspace(-1,4,100);

figure(1)

sens = feedback(1,G*K,1);
bode(sens,1/(gam*Wp),w);
title('Sensitivity plot')

figure(2)

contsens = feedback(K,G,1);
bode(contsens,1/(gam*Wu),w);
title('Control sensitivity plot')