5. Consider the feedback control system shown in Fig. 5. Let K = 0, i.e., the controller is an integral controller K(s) = K/s.
(5a) Determine the value of K so that the closed-loop system has a damping ratio ζ = 0.707.
(5b) Then find the natural frequency ωn and the transfer functions Y(s)/R(s) and U(s)/R(s) of the closed-loop system.
(5c) Plot the output response y(t) and control input u(t) due to the reference input r(t) = 20u(t) on separate graphs using these two transfer functions and the MATLAB step command.
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R(s)
E(s)
U(s)
Y(s)
145.5 G(s) = s + 43.14
Fig. 5
K(s)
G(s)
r(t) = 20u(t)
e(t)
u(t) = ?
y(t) = ?
K(s) = K + S