ziegler.m

使用ziegler函数可以直接设计出系统的PID类控制器

function [Gc,Kp,Ti,Td,H]=ziegler(key,vars)
Ti=[];Td=[];H=1;
if length(vars)==4,
    K=vars(1);L=vars(2);T=vars(3);N=vars(4);a=K*L/T;
    if key==1,Kp=1/a;
    elseif key==2,Kp=0.9/a;Ti=3.33*L;
    elseif key==3|key==4,Kp=1.2/a;Ti=2*L;Td=L/2;end
elseif length(vars)==3,
    K=vars(1);Tc=vars(2);N=vars(3);
    if key==1,Kp=0.5*K;
    elseif key==2,Kp=0.4*K;Ti=0.8*Tc;
    elseif key==3|key==4,Kp=0.6*K;Ti=0.5*Tc;Td=0.12*Tc;end
elseif length(vars)==5,
    K=vars(1);Tc=vars(2);rb=vars(3);N=vars(5);
    pb=pi*vars(4)/180;Kp=K*rb*cos(pb);
    if key==2,Ti=-Tc/(2*pi*tan(pb));
    elseif key==3|key==4,
        Ti=Tc*(1+sin(pb))/(pi*cos(pb));Td=Ti/4;
    end
end
switch key
    case 1,Gc=Kp;
    case 2,Gc=tf(Kp*[Ti,1],[Ti,0]);
    case 3,
        nn=[Kp*Ti*Td*(N+1)/N,Kp*(Ti+Td/N),Kp];
        dd=Ti*[Td/N,1,0];Gc=tf(nn,dd);
    case 4,
        d0=sqsrt(Ti*(Ti-4*Td));Ti0=Ti;Kp=0.5*(Ti+d0)*Kp/Ti;
        Ti=0.5*(Ti+d0);Td=Ti0-Ti;Gc=tf(Kp*[Ti,1],[Ti,0]);
        nH=[(1+Kp/N)*Ti*Td,Kp*(Ti+Td/N),kp];
        H=tf(nH,Kp*conv([Ti,1],[Td/N,1]));
    case 5,Gc=tf(Kp*[Td*(N+1)/N,1],[Td/N,1]);
end