figure(3)
clf;
clear;

robot = tf(1, [1 8 25]);		

Kp = 0.5;			% defines the proportional controller gain
Ki = 0.5;

t=0:0.01:2;

perturbation = 0;

picontroller=tf([Kp Ki], [1 0]);
picontrol=feedback(picontroller*robot+perturbation, 1);

figure(3)
step(picontrol)
title('PI control')
