aminit;

K=[];TI=[];PHM=[];WGC=[];P='1./(s+1).^4';str='b-.';
for wgc=0.1:0.1:0.5,
s=i*wgc;pgc=eval(P);
Ti=0.5/wgc;k=wgc*Ti/sqrt(1+wgc^2*Ti^2)/abs(pgc);K=[K,k];TI=[TI,Ti];
end;

str='b-.';
t=0:0.2:60;
for ij=1:5,
  k=K(ij);
  Ti=TI(ij)
  P=tf(1,[1 4 6 4 1]);C=tf(k*[Ti 1],[Ti 0]);
  y=step(P*C/(1+P*C),t);
  u=step(C/(1+P*C),t);
  subplot(3,2,1);
  pl=plot(t,y,str);hold on;
  ylabel('y');
  set(pl,'Linewidth', AM_data_linewidth);
  axis([0 60 0 2])
  subplot(3,2,3);
  pl=plot(t,u,str);hold on;
  set(pl,'Linewidth', AM_data_linewidth);
  xlabel('t');ylabel('u')
  axis([0 60 0 2])
  str='b-';
end

amprint('procctrl-pistep.eps');
