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%PID Controler for Square Tracking with Filtered Signal 
clear all; 
close all; 
 
ts=20; 
sys=tf([1],[60,1],'inputdelay',80); 
dsys=c2d(sys,ts,'zoh'); 
[num,den]=tfdata(dsys,'v'); 
 
u_1=0;u_2=0;u_3=0;u_4=0;u_5=0; 
y_1=0; 
error_1=0; 
ei=0; 
rin_1=0;rin_2=0; 
for k=1:1:1500 
time(k)=k*ts; 
 
rin(k)=1.0*sign(sin(0.00005*2*pi*k*ts)); 
 
M=1; 
switch M; 
case 1 
   rin(k)=rin(k); 
case 2 
   rin(k)=0.10*rin(k)+0.80*rin_1+0.10*rin_2; 
end 
 
%Linear model 
yout(k)=-den(2)*y_1+num(2)*u_5; 
 
kp=0.80; 
kd=10; 
ki=0.002; 
 
error(k)=rin(k)-yout(k); 
ei=ei+error(k)*ts; 
 
u(k)=kp*error(k)+kd*(error(k)-error_1)/ts+ki*ei; 
 
%Update parameters 
u_5=u_4;u_4=u_3;u_3=u_2;u_2=u_1;u_1=u(k); 
y_1=yout(k); 
    
error_2=error_1; 
error_1=error(k); 
rin_2=rin_1; 
rin_1=rin(k); 
end 
figure(1); 
plot(time,rin,'k',time,yout,'k'); 
xlabel('time(s)');ylabel('rin,yout'); 
figure(2); 
plot(time,u,'k'); 
xlabel('time(s)');ylabel('u');