Consider the block diagram in the Figure below: r(s) + ē(s) ū(s) K(s) T(s) G(s) The plant transfer function is G(8) = (1+0.25s)(1+0.55) and the controller is K(8) = 8+0.2 s+5 Use the Nyquist stability criterion to characterize the stability of the closed-loop system. O a. The closed-loop system is unstable. O b. None of the above. O c. The closed-loop system is marginally stable. O d. The closed-loop system is stable.
Consider the block diagram in the figure below: f(s) + ē(s) ū(s) y(s) K(s) G(s) The plant transfer function is G(s) = (x+1) 6+35+9) and the controller is K(s) = kp. Use the Nyquist plot to determine the maximum value of k, for closed-loop stability. O a. 3.4 O b.4.3 O c. 1.6 O d. 0.6 O e. 2.3