%  Figure 3.27     Feedback Control of Dynamic Systems, 8e
%                        Franklin, Powell, Emami
% script to generate Fig. 3.27

clf;

s=tf('s');

%zeta = 0.5;
zeta = 0.707;

k=1/zeta;
set_a = [ 100 4 2 1 ];

for i = 1:4

a = set_a(i);
sys = (k/a*s+1)/(s^2+2*zeta*s+1);
t = 0:.1:10;
y = step(sys,t);

figure(1)
plot( t , y, '-','LineWidth',2);
grid on;
axis( [0, 10, -0.1, 1.8 ])
hold on;

pause(2)
end

%%%%%%%%%%%%%%%%

%sys1=1/((s^2+2*zeta*s+1)*(k/a*s+1));
