tut1pr3.m

Robust自动控制讲义

%Solution of Tutorial 1 - Problem 3.
% Plant model
s=tf('s');
G = (s^2 + 0.18*s + 0.08)/(s^2 +0.3*s + 0.02);
% weight Wp
M=1; wb=0.1; A=0.01; Wp = (1/M*s+wb)/(s+wb*A);  
% Uncertainty weight Wt.
Wt = (10*s+0.33)/(1.9*s+1)
%Control weight
Wu=0;              
% Controller design
[Kss,N,N_norm,INFO]=mixsyn(G,Wp,Wu,Wt);
K = tf(Kss);

L=G*K;  % loop transfer function
S=inv(1+L); % Sensitivity
T=1-S;      % complementary sensitivity
figure;
step(T,100);
figure;
w=logspace(-5,3);
frsp_S = freqresp(S,w);
frsp_T = freqresp(T,w);
frsp_bound_S = freqresp(1/Wp,w);
frsp_bound_T = freqresp(1/Wt,w);
loglog(w, abs(frsp_S(:)),w,abs(frsp_bound_S(:)),'.-' );
title('|S|(-) and |1/Wp| (-.)');figure;
loglog(w, abs(frsp_T(:)),w,abs(frsp_bound_T(:)),'.-' );
title('|T|(-) and |1/Wt| (-.)');