ex8_27.m

华东理工大学自动化系《控制系统分析、设计和应用》教材配套程序实例,有关说明： 1. 安装MATLAB软件。安装时

% ex8_27
% 计算原系统的闭环系统和状态反馈组成的闭环系统的灵敏度
% 比较中，设参数变化有时间常数（开环极点的倒数）和前向放大系数
figure('pos',[50,50,200,250],'color','w');
axes('pos',[0.15,0.6,.75,.35]);
syms p1 p2 K s k1 k2 k3;
T=10*K/(s^3-(p1+p2)*s^2+p1*p2*s+10*K);
S1=subs(jacobian(T,p1)*p1/T,{p1,p2,K},{-1,-5,0.21});
[num,den]=numden(S1);
num=sym2poly(num);
den=sym2poly(den);
w=0:0.01:3;
G1=tf(num,den);
[mag,phase]=bode(G1,w);
plot(w,shiftdim(mag,2));
S2=subs(jacobian(T,p2)*p2/T,{p1,p2,K},{-1,-5,0.21});
hold on;
[num,den]=numden(S2);
num=sym2poly(num);
den=sym2poly(den);
G2=tf(num,den);
[mag,phase]=bode(G2,w);
plot(w,shiftdim(mag,2));
S3=subs(jacobian(T,K)*K/T,{p1,p2,K},{-1,-5,0.21});
[num,den]=numden(S3);
num=sym2poly(num);
den=sym2poly(den);
G3=tf(num,den);
[mag,phase]=bode(G3,w);
plot(w,shiftdim(mag,2));
set(gca,'fonts',8,'fontw','b');
axis([0 3 0 1.5]);
axes('pos',[0.15,0.13,.75,.35]);
Ts=10*K/(s^3+(2*K*k3-(p1+p2))*s^2+(p1*p2+10*K*(k3+k2))*s+10*K*k1);
Ss1=subs(jacobian(Ts,p1)*p1/T,{p1,p2,K,k1,k2,k3},{-1,-5,0.21,1,-3.393,4.77});
[num,den]=numden(Ss1);
num=sym2poly(num);
den=sym2poly(den);
Gs1=tf(num,den);
[mag,phase]=bode(Gs1,w);
plot(w,shiftdim(mag,2))
Ss2=subs(jacobian(Ts,p2)*p2/T,{p1,p2,K,k1,k2,k3},{-1,-5,0.21,1,-3.393,4.77});
[num,den]=numden(Ss2);
num=sym2poly(num);
den=sym2poly(den);
hold on;
Gs2=tf(num,den);
[mag,phase]=bode(Gs2,w);
plot(w,shiftdim(mag,2))
Ss3=subs(jacobian(Ts,K)*K/T,{p1,p2,K,k1,k2,k3},{-1,-5,0.21,1,-3.393,4.77});
[num,den]=numden(Ss3);
num=sym2poly(num);
den=sym2poly(den);
Gs3=tf(num,den);
[mag,phase]=bode(Gs3,w);
plot(w,shiftdim(mag,2))
set(gca,'fonts',8,'fontw','b');
axis([0 3 0 0.6])