getfolpd.m

控制系统计算机辅助设计——MATLAB语言与应用(源代码）

function [K,L,T,G1]=getfolpd(key,G)
switch key
case 1, [y,t]=step(G); 
   fun = inline('x(1)*(1-exp(-(t-x(2))/x(3))).*(t>x(2))','x','t');
   x=lsqcurvefit(fun,[1 1 1],t,y); K=x(1); L=x(2); T=x(3);
case 2, [Kc,Pm,wc,wcp]=margin(G); 
   ikey=0; L=1.6*pi/(3*wc); K=dcgain(G); T=0.5*Kc*K*L; 
   if finite(Kc), x0=[L;T]; 
      while ikey==0, u=wc*x0(1); v=wc*x0(2); 
          FF=[K*Kc*(cos(u)-v*sin(u))+1+v^2; sin(u)+v*cos(u)];
          J=[-K*Kc*wc*sin(u)-K*Kc*wc*v*cos(u),-K*Kc*wc*sin(u)+2*wc*v;
              wc*cos(u)-wc*v*sin(u), wc*cos(u)]; x1=x0-inv(J)*FF; 
      if norm(x1-x0)<1e-8, ikey=1; else, x0=x1; end, end
      L=x0(1); T=x0(2);  end
case 3, [n1,d1]=tfderv(G.num{1},G.den{1}); 
   [n2,d2]=tfderv(n1,d1); K1=dcgain(n1,d1); 
   K2=dcgain(n2,d2); K=dcgain(G); Tar=-K1/K; T=sqrt(K2/K-Tar^2); L=Tar-T;
case 4
   Gr=opt_app(G,0,1,1);  L=Gr.ioDelay;
   T=Gr.den{1}(1)/Gr.den{1}(2); K=Gr.num{1}(end)/Gr.den{1}(2);
end
G1=tf(K,[T 1],'iodelay',L);
function [e,f]=tfderv(b,a)
f=conv(a,a); na=length(a); nb=length(b); 
e1=conv((nb-1:-1:1).*b(1:end-1),a);
e2=conv((na-1:-1:1).* a(1:end-1),b); maxL=max(length(e1),length(e2));
e=[zeros(1,maxL-length(e1)) e1]-[zeros(1,maxL-length(e2)) e2];