fig135.m

realize analysis and design for computer-controlled system

% Generates Fig 13.5 (recurres)
% Using the System Identification Toolbox
% Computer Controlled Systems (3rd ed)
% Author: B. Wittenmark
% Last edit: 1997-08-04
% Copyright (c) 1996 by K. J. 舠tr鰉, B. Wittenmark and
% Department of Automatic Control, Lund Institute of
% Technology, Lund, Sweden

newplot;clf
set(gcf,'PaperUnits','centimeters','PaperPosition',[2 2 13 10])
set(gcf,'Units','centimeters','position',get(gcf,'PaperPosition'))

lw=0.9;

N=500;
a1=-0.8;
b1=0.5;
sig=0.5;
P0=10;

model=poly2th([1 a1],[0 b1]);
u=idinput(600,'prbs',[0 1/5]);
u=-u(1:N);
randn('seed',217);
e=sig*randn(N,1);
y=idsim([u e],model);
mydata=[y u];
[thm,yh,P]=rarx(mydata,[1 1 1],'ff',1,[0 0],P0*eye(2));
thm(N,:)
P

ts=[1:N];
subplot(2,1,1)
plot(ts,thm(:,1),'k-',ts,thm(:,2),'k-','Linew',lw);
hold on
plot([0 N],[a1 a1],'k--',[0 N],[b1 b1],'k--','Linew',lw);
axis([0 N -1.5 1.5]);
set(gca,'Fontsize',9,'Fontname','NewCenturySchlbk');
set(gca,'xtick',[0 N],'ytick',[-1 0 1]);
text(200,0.9,'\it{b}','Fontsize',9,'Fontname','NewCenturySchlbk')
a=hex2dec('d9');
text(201,1.1,setstr(a),'fontname','symbol','fontsize',7)
text(200,-0.4,'\it{a}','Fontsize',9,'Fontname','NewCenturySchlbk')
text(201,-0.26,setstr(a),'fontname','symbol','fontsize',7)
ylabel('Parameter estimates','Fontsize',9,'Fontname','NewCenturySchlbk')
xlabel('Time','Fontsize',9,'Fontname','NewCenturySchlbk')