www.pudn.com > chap1.rar > chap1_18.m

%PID Controller with Partial differential 
clear all; 
close all; 
 
ts=0.001; 
sys=tf(5.235e005,[1,87.35,1.047e004,0]); 
dsys=c2d(sys,ts,'z'); 
[num,den]=tfdata(dsys,'v'); 
 
u_1=0;u_2=0;u_3=0;u_4=0;u_5=0; 
y_1=0;y_2=0;y_3=0; 
yy_1=0; 
error_1=0;error_2=0;ei=0; 
 
kp=0.20;ki=0.05; 
 
sys1=tf([1],[0.04,1]);   %Low Freq Signal Filter 
dsys1=c2d(sys1,ts,'tucsin'); 
[num1,den1]=tfdata(dsys1,'v'); 
f_1=0; 
 
M=3; 
for k=1:1:1000 
time(k)=k*ts; 
 
rin(k)=20;  %Step Signal 
 
%Linear model 
yout(k)=-den(2)*y_1-den(3)*y_2-den(4)*y_3+num(2)*u_1+... 
        num(3)*u_2+num(4)*u_3; 
      
if M==1                 %No disturbance signal 
   error(k)=rin(k)-yout(k);  
   filty(k)=yout(k); 
end 
 
D(k)=5.0*rands(1);      %Disturbance signal 
yyout(k)=yout(k)+D(k); 
 
if M==2                 %No filter 
   filty(k)=yyout(k); 
   error(k)=rin(k)-filty(k); 
end 
if M==3                 %Using low frequency filter 
   filty(k)=-den1(2)*f_1+num1(1)*(yyout(k)+yy_1); 
   error(k)=rin(k)-filty(k); 
end 
 
%I separation 
if abs(error(k))<=0.8 
   ei=ei+error(k)*ts; 
else 
   ei=0; 
end 
   u(k)=kp*error(k)+ki*ei; 
 
if u(k)>=10       % Restricting the output of controller 
   u(k)=10; 
end 
if u(k)<=-10 
   u(k)=-10; 
end 
%----------Return of PID parameters------------ 
rin_1=rin(k); 
u_5=u_4;u_4=u_3;u_3=u_2;u_2=u_1;u_1=u(k);    
y_3=y_2;y_2=y_1;y_1=yout(k); 
 
f_1=filty(k); 
yy_1=yyout(k); 
 
error_2=error_1; 
error_1=error(k); 
end 
figure(1); 
subplot(211); 
plot(time,rin,'b',time,filty,'r'); 
xlabel('time(s)');ylabel('rin,yout'); 
subplot(212); 
plot(time,u,'r'); 
xlabel('time(s)');ylabel('u'); 
figure(2); 
plot(time,D,'r'); 
xlabel('time(s)');ylabel('Disturbance signal');