Question
Problem 2. Given the same plant as Problem 1, you now want to completely eliminate the steady-state error of the closed-loop system with a PI controller. r(t) + e(t) u(t) y(t) Ge Gp 4 y(t) Ge(s) = kp + kĮ 5 kps + ki Gp(s) =- 4s + 1 2 (a) Show that the closed-loop transfer function is 2(kps +ki) Gel(s) = 5 4s2 + (1 + 2kp)s + 2kj (b) From this transfer function, find equations for the natural frequency W), and damping ratio { in terms of the controller gains. (c) Find the DC gain of the transfer function. Comment on the steady-state error of the closed-loop system. (d) Find the gains kp and kį for the closed loop transfer function to have @n =1 and { =1 (critical damping). (e) Find the poles of the closed-loop system with the controller gains from (d). (f) Use MATLAB to create a single plot with 2 step response traces: one for the open loop plant and one for the closed-loop system designed in (d).
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