Question: 1 -

The gain margin for the system with open loop transfer function

G(s)H(s) = 2(1+s)/s²

0

-∞

∞

1

Answer:

∞

Solution:

∠G(s)H(s) = −180° + tan⁻¹ω

Question: 2 -

The system shown in the figure remains stable when

−1< K <1

K < −1

1< K < 3

K < −3

Answer:

K < −3

Solution:

Y(s)/R(s) = (K/s)/{1-(3/s+k/s)} = K/s-(3+K)

 

Question: 3 -

The feedback control system in the figure is stable.

only if 0 ≤ K ≤1

onlyif 0 ≤ K <1

only is K ≥ 0

for all K ≥ 0

Answer:

onlyif 0 ≤ K <1

Solution:

TF= G1G2/1+H1G1G2

then use Routh's Array.

Question: 4 -

The phase margin of a system wit the open-loop transfer function

G(s)H(s) = (1-s)/(1+s)(2+s)

∞

0°

63.4°

90°

Answer:

∞

Solution:

|G(s).H(s)|= 1

Question: 5 -

The characteristic polynomial of a system is

q(s) = 2s⁵+s⁴+4s³+2s²+2s+1

The system is

marginally stable

unstable

stable

oscillatory

Answer:

unstable

Solution not available.