Question:-
A unity negative feedback closed loop system has a plant with the transfer function G(s) = (1 /(s2+2s+2)) and a controller Gc(S) in the feed forward path. For a unit set input, the transfer function of the controller that gives minimum steady state error is
Option (A)
Gc(s) = (s+1)/(s+2)
Option (B)
Gc(s) = (s+2)/(s+1)
Option(C)
Gc = (s+1)(S+4) / (s+2)(s+3)
Option(D)
Gc(s) = 1+ (2/s) + 3s
Correct Option:
(D)
Question Solution:
E(s) = { sR(s) / (1+[G(s) + Gc(s)] H(s) }

So, Gc(s)|s ®0 should be maximum for error = ¥ Gc (s)|s ®0
question-answer-faq-2183