pid_objfun_itae.m

-PID controller has been extensively used in the industrial world. But in this controller it is dif

%PID_objfun_ITAE.m
%Written by Ian Griffin July 2003
%Last Modified 20-08-03
%____________________________________________________________________
function [x_pop, fx_val]=PID_objfun_ITAE(x_pop,options)
global sys_controlled
global time
global sysrl
%____________________________________________________________________
Kp=x_pop(2);
Ki=x_pop(3);
Kd=x_pop(1);
%Creating the PID controller from current values
pid_den=[1 0];
pid_num=[Kd Kp Ki];
pid_sys=tf(pid_num,pid_den); %overall PID controller
%Creating PID feedback loop
sys_series=series(pid_sys,sysrl);
sys_controlled=feedback(sys_series,1);
%____________________________________________________________________
time =0:0.1:30;
[y t] = step(sys_controlled,time); % Step response of closed-loop
for i=1:301
error(i) = (abs(1-y(i)))*t(i);
end
%Integral of Squared Error
ITAE=sum(error);

%____________________________________________________________________
%to make sure controlled system is stable
poles=pole(sys_controlled);
if poles(1)>0
ITAE=100e300;
elseif poles(2)>0
ITAE=100e300;
elseif poles(3)>0
ITAE=100e300;
elseif poles(4)>0
ITAE=100e300;
elseif poles(5)>0
ITAE=100e300;
end
fx_val=1/ITAE;
%____________________________________________________________________