P2.35 A feedback control system has the structure shown in Figure P2.35. Determine the closed-loop transfer function Y(s)/R(s)

(a) by block diagram manipulation and

(b) by using a signal-flow graph and Mason’s signal-

flow gain formula.

(c) Select the for a unit step input. What is the time required for the step response to reach 90% of its final value?

+ R(s) K s+1 + K Y(s) S FIGURE P2.35 Multiloop feedback system.