Question Six A feedback control architecture is given in Figure 4 in which Gc(s) is a PI controller to be designed and G(s) is plant transfer function. X(s) E(s) Ge(s) Y(s) G(s) Figure 4.Control architecture for question six G(s) 1 (s + 3)(s +6) a) Determine the reference complex coordinate corresponding to the following design specifications: Zero steady-state error for step input; time constant of 0.25 seconds; and damping ratio of 0.6247 (7 marks) Given that Ge(s) has the following transfer function: b) Page 4 of 6 Scanned kp(s +2.) Gc(s) = = S Where: Zo ki kp (13 marks) Determine the location of zo on the complex plane