How to set the frequency range of a nyquist plot?

I use the following command to draw a Nyquist plot a dynamic transfer function:

s=tf('s');

G0=(d_x*(d_Fx*SYSD{1,1}+d_Fy*SYSD{2,1}+d_Fz*SYSD{3,1})+...

d_y*(d_Fx*SYSD{2,1}+d_Fy*SYSD{2,2}+d_Fz*SYSD{3,2})+...

d_z*(d_Fx*SYSD{3,1}+d_Fy*SYSD{3,2}+d_Fz*SYSD{3,3}))*(...

exp(-T_t*s)-1)*b*k_cb;

figure(8);

NyquistPlot=nyquistplot(G0);

setoptions(NyquistPlot,'ShowFullContour','off','FreqUnits','Hz','Grid','off');

CurrentPlots=get(gca,'children');

set(CurrentPlots(1),'DisplayName',['a_p=',num2str(a_p),' mm']);

set(gcf,'color','w');

set(gca, 'XMinorGrid','on', 'YMinorGrid','on');

legend('Location','best');

title('Ortskurve von G_0(jw)');

hold on;

xline(1,'HandleVisibility','off');

For the purpose of my analysis, I only need Nyquist plot from 20 Hz to 200 Hz range and I want to hide the Nyquist curve outside the abovementioned frequency range. However I didn't find any option about manipulating the frequency limit of the curve.

Answer 1

[Cris LaPierre]

You should be able to set the freqeuncy range using the following syntax:

• h = nyquistplot(___,w) plots Nyquist diagram for frequencies specified by the frequencies in w.
• If w is a cell array of the form {wmin,wmax}, then nyquistplot plots the Nyquist diagram at frequencies ranging between wmin and wmax.
• Specify frequencies in units of rad/TimeUnit, where TimeUnit is the TimeUnit property of the model.

See here for more.

load TransferFcnNyquist.mat

s=tf('s');
G0=(d_x*(d_Fx*SYSD{1,1}+d_Fy*SYSD{2,1}+d_Fz*SYSD{3,1})+...
    d_y*(d_Fx*SYSD{2,1}+d_Fy*SYSD{2,2}+d_Fz*SYSD{3,2})+...
    d_z*(d_Fx*SYSD{3,1}+d_Fy*SYSD{3,2}+d_Fz*SYSD{3,3}))*(...
    exp(-T_t*s)-1)*b*k_cb;

figure(8);
NyquistPlot=nyquistplot(G0,{20*2*pi,200*2*pi});
%                          ^^^^^^^^^^^^^^^^^^ specify range in rad
setoptions(NyquistPlot,'ShowFullContour','off','FreqUnits','Hz','Grid','off');

CurrentPlots=get(gca,'children');
set(CurrentPlots(1),'DisplayName',['a_p=',num2str(a_p),' mm']);
set(gcf,'color','w');
set(gca, 'XMinorGrid','on', 'YMinorGrid','on');
legend('Location','best');
title('Ortskurve von G_0(jw)');
xline(1,'HandleVisibility','off');