AP5.5 A system with a controller is shown in Figure AP5.5. The zero of the controller may be varied.

(a) Determine the steady-state error for a unit step input for α = 0 and α ≠ 0.

(b) Let α = 1, 15, and 75. Plot the response of the system to a unit step input disturbance for the three values of α. Compare the results, and se

lect the best value of the three values of α.