% ***** MATLAB Code Starts Here %
%NYQUIST_02_MAT
%
fig_size = [232 84 774 624];
% System 1 -- all open-loop poles & zeros in LHP
%
olz1 = [-0.5;-10]; olp1 = [-0.3;-5;-20;-20];
num1 = 250 * real(poly(olz1));
den1 = real(poly(olp1));
[re1,im1] = nyquist(num1,den1);
figure(1),clf,plot(re1,im1,
'b',re1,-im1,'r--'),plotax,set(gcf,'Position',fig_size),... title('System #1: All open-loop poles in LHP, All open-loop zeros in LHP'),... v=axis;nyquist_arrow(re1,im1,v);%
% System 2 -- one open-loop zero in RHP, all open-loop poles in LHP
%
olz2 = [0.5;-10]; olp2 = [-0.3;-5;-20;-20];
num2 = 250 * real(poly(olz2));
den2 = real(poly(olp2));
[re2,im2] = nyquist(num2,den2);
figure(2),clf,plot(re2,im2,
'b',re2,-im2,'r--'),plotax,set(gcf,'Position',fig_size),...title(
'System #2: All open-loop poles in LHP, 1 open-loop zero in RHP'),... v=axis;nyquist_arrow(re2,im2,v);%
% System 3 -- one open-loop zero and one open-loop pole in RHP
%
olz3 = [0.5;-10]; olp3 = [0.3;-5;-20;-20];
num3 = 250 * real(poly(olz3));
den3 = real(poly(olp3));
[re3,im3] = nyquist(num3,den3);
figure(3),clf,plot(re3,im3,
'b',re3,-im3,'r--'),plotax,set(gcf,'Position',fig_size),...title(
'System #3: 1 open-loop pole in RHP, 1 open-loop zero in RHP'),... v=axis;nyquist_arrow(re3,im3,v);%
% System 4 -- one open-loop pole in RHP, all open-loop zeros in LHP
%
olz4 = [-0.5;-10]; olp4 = [0.3;-5;-20;-20];
num4 = 250 * real(poly(olz4));
den4 = real(poly(olp4));
[re4,im4] = nyquist(num4,den4);
figure(4),clf,plot(re4,im4,
'b',re4,-im4,'r--'),plotax,set(gcf,'Position',fig_size),...title(
'System #4: 1 open-loop pole in RHP, All open-loop zeros in LHP'),... v=axis;nyquist_arrow(re4,im4,v);%
% Form the closed-loop characteritics equations
%
dcl(1,:) = den1 + [0 0 num1];
dcl(2,:) = den2 + [0 0 num2];
dcl(3,:) = den3 + [0 0 num3];
dcl(4,:) = den4 + [0 0 num4];
%
% Find the closed-loop poles
%
for
i = 1:4clp(:,i) = roots(dcl(i,:));
end
%
clear i
% % ***** MATLAB Code Stops Here
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Lastest revision on Wednesday, June 7, 2006 12:39 PM