fig523.m

realize analysis and design for computer-controlled system

% Generates Fig 5.23
% Computer Controlled Systems (3rd ed)
% Author: B. Wittenmark
% Last edit: 1997-07-04
% Copyright (c) 1996 by K. J. 舠tr鰉, B. Wittenmark and
% Department of Automatic Control, Lund Institute of
% Technology, Lund, Sweden

newplot;clf;
lw=0.9;
set(gcf,'PaperUnits','centimeters','PaperPosition',[2 2 13 9.5])
set(gcf,'Units','centimeters','position',get(gcf,'PaperPosition'))

h=0.2;

r1= -0.18619619;
r2=0;
s0=5.6636344;
s1=-5.4699074;
s2=0;

be=cos(h);
apol=[1 -2*be 1];
bpol=(1-be)*[1 1];
rpol=[1 r1 r2];
spol=[s0 s1 s2];
alg=conv(apol,rpol);
blg=conv(bpol,spol);
wrad1=logspace(-3,pi,500)/h;
[mag1,ph1,wrad1]=dbode(blg,alg,h,wrad1);
ph1(330:500)=ph1(330:500)-360;

r1=-1.0750296;
r2=7.50296096e-02;
s0=12.830898;
s1=-22.864403;
s2=10.466061;
rpol=[1 r1 r2];
spol=[s0 s1 s2];
alg=conv(apol,rpol);
blg=conv(bpol,spol);
wrad2=logspace(-3,pi,500)/h;
[mag2,ph2,wrad2]=dbode(blg,alg,h,wrad2);

subplot(2,1,1)
loglog(wrad2,mag2,'k-','Linew',lw)
axis([0.01 10 0.01 10000])
set(gca,'Fontsize',9,'Fontname','NewCenturySchlbk');
set(gca,'ytick',[0.01 1 100 10000]);
set(gca,'xtick',[0.01 0.1 1 10]);
ylabel('Gain','Fontname','NewCenturySchlbk','Fontsize',9)
hold on
plot([0.01 10],[1 1],'k:','Linew',lw)

subplot(2,1,2)
%ph1=ph1-360*ones(length(ph1),1);
%ph2=ph2-360*ones(length(ph2),1);
semilogx(wrad2,ph2,'k-','Linew',lw)
axis([0.01 10 -300 100]);
set(gca,'Fontsize',9,'Fontname','NewCenturySchlbk');
set(gca,'xtick',[0.01 0.1 1 10]);
set(gca,'ytick',[-300 -200 -100 0 100]);
xlabel('Frequency, rad/s','Fontname','NewCenturySchlbk','Fontsize',9)
ylabel('Phase','Fontname','NewCenturySchlbk','Fontsize',9)
hold on
plot([0.01 10],[-180 -180],'k:','Linew',lw)