q7.m

Robust自动控制讲义

% Uses the robust control toolbox from Matlab v. 7
% Mixed sensitivity design

 close all;

 % Part (b)
 
 s = tf('s'); % Laplace transform variable 's'.
 G = (4*s+1)/((s-0.01)*(s^2+0.1*s+1)); % plant to be controlled 
 Gss=ss(G);
 Wp=(0.5*s+10)/(s+0.01); % Sensitivity weight
 Wu=[0.001];                % Control weight
 Wt=(2*s+1)/(10*s+2); % Complementary sensitivity weight
 [Kss,N,N_norm,INFO]=mixsyn(Gss,Wp,Wu,Wt);
 K = tf(Kss);
 Kzp=zpk(K)
 
 % Part (c)
 
 L=G*K;  % loop transfer function
 S=inv(1+L); % Sensitivity
 T=1-S;      % complementary sensitivity
 [Gm,Pm,wcg,wcp] = margin(L); % Calculate the gain margin and phase margins.
 Gm_dB = 20*log10(Gm);
 
 % Part (d)
 
 figure;
 step(T);
 figure;
 sigma(S,1/Wp,'-.');title('|S|(-) and |1/Wp| (-.)');
 figure;
 sigma(T,1/Wt,'-.');title('|T| (-) and |1/Wt| (-.)');