%PID Feedforward Controler
clear all;
close all;

ts=0.001;
sys=tf(133,[1,25,0]);
dsys=c2d(sys,ts,'z');
[num,den]=tfdata(dsys,'v');

u_1=0;u_2=0;
y_1=0;y_2=0;

error_1=0;ei=0;
for k=1:1:1000
time(k)=k*ts;
   
A=0.5;F=3.0;
rin(k)=A*sin(F*2*pi*k*ts); 
drin(k)=A*F*2*pi*cos(F*2*pi*k*ts);
ddrin(k)=-A*F*2*pi*F*2*pi*sin(F*2*pi*k*ts);

%Linear model
yout(k)=-den(2)*y_1-den(3)*y_2+num(2)*u_1+num(3)*u_2;

error(k)=rin(k)-yout(k);

ei=ei+error(k)*ts;

up(k)=80*error(k)+20*ei+2.0*(error(k)-error_1)/ts;

uf(k)=25/133*drin(k)+1/133*ddrin(k);

M=2;
if M==1        %Only using PID
	u(k)=up(k);
elseif M==2    %PID+Feedforward
	u(k)=up(k)+uf(k);
end

if u(k)>=10
   u(k)=10;
end
if u(k)<=-10
   u(k)=-10;
end

u_2=u_1;u_1=u(k);
y_2=y_1;y_1=yout(k);
error_1=error(k);
end
figure(1);
plot(time,rin,'r',time,yout,'b');
xlabel('time(s)');ylabel('rin,yout');
figure(2);
plot(time,error,'r');
xlabel('time(s)');ylabel('error');
figure(3);
plot(time,up,'k',time,uf,'b',time,u,'r');
xlabel('time(s)');ylabel('up,uf,u');