ex6_2.m

反馈控制系统设计与分析（matlab程序）

Gc2=tf([0.5 1],[2.5,1]); G=tf(100,[0.04,1,0]); G_o=Gc2*G;
[Gm,Pm,Wcg,Wcp]=margin(G_o); [Gm,Pm,Wcg,Wcp]

[m,p]=bode(G,w); [m1,p1]=bode(G_o,w);
subplot(211), semilogx(w,20*log10([m(:),m1(:)]))
subplot(212), semilogx(w,[p(:),p1(:)])
G_c1=feedback(G,1); G_c2=feedback(G_o,1);
G_c3=feedback(Gc1*G,1); 
[y,t]=step(G_c1); y=[y,step(G_c2,t),step(G_c3,t)]; 
figure, plot(t,y)

T=[0.5,1,2.5,5,10,20]; G=tf(100,[0.04,1,0]);
f1=figure;  f2=figure; y=[]; m=[]; p=[];
w=logspace(-2,2);
for i=1:length(T)
   Gc2=tf([0.2*T(i) 1],[T(i),1]);
   G_o=G*Gc2; G_c=feedback(G_o,1);
   [mm,pp]=bode(G_o,w);
   y=[y,step(G_c,t)];
   m=[m,mm(:)]; p=[p,pp(:)];
end
figure(f1), 
subplot(211), semilogx(w,20*log10(m)) 
subplot(212), semilogx(w,p)
figure(f2), plot(t,y)