www.pudn.com > mohu.rar > CHAP1_12.M

%PID Controler with Partial differential 
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; 
ud_1=0; 
y_1=0;y_2=0;y_3=0; 
error_1=0; 
ei=0; 
 
for k=1:1:100 
time(k)=k*ts; 
 
rin(k)=1.0; 
 
%Linear model 
yout(k)=-den(2)*y_1+num(2)*u_5; 
 
D(k)=0.01*rands(1); 
yout(k)=yout(k)+D(k); 
 
error(k)=rin(k)-yout(k); 
 
%PID Controller with partly differential 
ei=ei+error(k)*ts; 
kc=0.30; 
ki=0.0055; 
TD=140; 
 
kd=kc*TD/ts; 
 
Tf=180; 
Q=tf([1],[Tf,1]);   %Low Freq Signal Filter 
 
M=1; 
if M==1      %Using PID with Partial differential 
	alfa=Tf/(ts+Tf); 
	ud(k)=kd*(1-alfa)*(error(k)-error_1)+alfa*ud_1; 
	u(k)=kc*error(k)+ud(k)+ki*ei; 
   ud_1=ud(k); 
elseif M==2  %Using Simple PID 
	u(k)=kc*error(k)+kd*(error(k)-error_1)+ki*ei; 
end 
 
%Restricting the output of controller 
if u(k)>=10 
   u(k)=10; 
end 
if u(k)<=-10 
   u(k)=-10; 
end 
 
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); 
error_1=error(k); 
end 
figure(1); 
plot(time,rin,'b',time,yout,'r'); 
xlabel('time(s)');ylabel('rin,yout'); 
figure(2); 
plot(time,u,'r'); 
xlabel('time(s)');ylabel('u'); 
figure(3); 
plot(time,rin-yout,'r'); 
xlabel('time(s)');ylabel('error'); 
figure(4); 
bode(Q,'r'); 
dcgain(Q);