The Nyquist stability criterion and the Routh criterion both are powerful analysis tools for
determining the stability of feedback controllers. Identify which of the following statements
is FALSE.
A
The closed-loop frequency response for a unity feedback system cannot be obtained
from the Nyquist plot.
B
The Routh criterion is not applicable in the condition of transport lag, which can be
readily handled by the Nyquist criterion.
C
The general shape of the Nyquist plot is readily obtained from the Bode magnitude plot
for all minimum-phase systems.
D
Both the criteria provide information relative to the stable gain range of the system.
2
GATE ECE 2018
Numerical
+2
-0.67
The figure below shows the Bode magnitude and phase plots of a stable transfer function
Consider the negative unity feedback configuration with gain k in the feedforward path.
The closed loop is stable for k < k0. The maximum value of k0 is ______.
Your input ____
3
GATE ECE 2018
MCQ (Single Correct Answer)
+1
-0.33
Consider p(s) = s3 + $${a_2}$$s2 + $${a_1}$$s + $${a_0}$$ with all real coefficients. It is known that its
derivative p'(s) has no real roots. The number of real roots of p(s) is
A
0
B
1
C
2
D
3
4
GATE ECE 2018
Numerical
+2
-0.67
For a unity feedback control system with the forward path transfer function
$$G(s) = {K \over {s\left( {s + 2} \right)}}$$
The peak resonant magnitude Mr
of the closed-loop frequency response is 2. The
corresponding value of the gain
K
(correct to two decimal places) is _________.
