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 = 1/((s+0.01)*(s-0.01))
 
 
  Wp=100/(s^3+2*s^2+2*s+1); % Sensitivity weight

 Wu=0.000;

 Wi= 0.1*s/(0.05*s+1); % Complementary sensitivity weight
 [Kss,N,N_norm,INFO]=mixsyn(G,Wp,Wu,Wi);
 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,10);
 figure;
 sigma(S,1/Wp,'-.');title('|S|(-) and |1/Wp| (-.)');
 figure;
 sigma(T,1/Wi,'-.');title('|T| (-) and |1/Wi| (-.)');