ex8_20.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_20
% 确定关联系统的稳定性
num={[1],[5];[1],[2]};
den={[0.1 1],[1 1];[0.5 1],[0.4 1]};
G=tf(num,den);
sp=0.1;
n=30;
syms Kc1 Kc2 x;
Gon11=poly2sym(G.num{1,1});Gon12=poly2sym(G.num{1,2});
Gon21=poly2sym(G.num{2,1});Gon22=poly2sym(G.num{2,2});
God11=poly2sym(G.den{1,1});God12=poly2sym(G.den{1,2});
God21=poly2sym(G.den{2,1});God22=poly2sym(G.den{2,2});
[x1]=solve(God11+Kc1*Gon11,'x');
[x2]=solve(God22+Kc2*Gon22,'x');
Kc1=solve(x1,'Kc1');
Kc2=solve(x2,'Kc2');
Kc1=sym2poly(Kc1),
Kc2=sym2poly(Kc2)
syms Kc1 Kc2;
qu1=simple((God11+Kc1*Gon11)*(God22+Kc2*Gon22)*God12*God21);
qu2=simple(Kc1*Kc2*Gon12*Gon21*God11*God22);
for j=1:n;
    Kc2=1+sp*j,
    for i=1:n;
        Kc1=1+sp*i;
        qs=subs(qu1-qu2,{'Kc1','Kc2'},{Kc1 Kc2});
        sy(:,i,j)=roots(sym2poly(qs));
    end;
end;
Z=shiftdim(sy,1);
figure('pos',[50,50,200,150],'color','w');
[X,Y]=meshgrid(1+sp:sp:Kc1,1+sp:sp:Kc2);
surf(X,Y,Z(:,:,4));shading interp;
axis([1 4 1 4 0 1])