www.pudn.com > chap1.rar > chap1_27.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; 
 
kp=0.12;ki=0.015; 
x=[0,0]; 
for k=1:1:3000 
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; 
      
D(k)=0.50*rands(1);  %Disturbance signal 
yyout(k)=yout(k)+D(k); 
 
M=1; 
if M==1             %No filter 
   filty(k)=yyout(k); 
elseif M==2         %Using filter with tracker and differentiation 
r=2000; 
h=0.02; 
T=ts; 
 
delta=r*h;  
delta0=delta*h;  
y=x(1)-yyout(k)+h*x(2); 
a0=sqrt(delta*delta+8*r*abs(y)); 
if abs(y)<=delta0 
    a=x(2)+y/h; 
else 
    a=x(2)+0.5*(a0-delta)*sign(y); 
end 
if abs(a)<=delta 
   fst2=-r*a/delta; 
else 
   fst2=-r*sign(a); 
end 
      
x(1)=x(1)+T*x(2); 
x(2)=x(2)+T*fst2; 
filty(k)=x(1); 
end 
 
error(k)=rin(k)-filty(k); 
%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); 
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'); 
 
figure(3); 
plot(time,yyout,'r',time,filty,'b'); 
xlabel('time(s)');ylabel('ideal signal,practical signal');