GATE IN topic:control-systems PYQs & Answers — Page 3

Questions 21–30 of 56. Imported answers require independent review unless marked reviewed.

Topic practice 56 questionsPage 3 of 6

A unity-gain negative-feedback control system has a loop-gain

given by

The closed-loop system is ______

Your answerChoose one option.

Causal and stable

Causal and unstable

Non-causal and stable

Non-causal and unstable

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The transfer function of a system is:

In the state-space representation of the system, the minimum number of state variables (in integer) necessary is ______

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The signal flow graph of a system is shown. The expression for

is ________

Diagram for Instrumentation Engineering question 37

Your answerChoose one option.

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A proportional-integral-derivative (PID) controller is employed to stably control a plant with transfer function

. Now, the proportional gain is increased by a factor of 2, the integral gain is increased by a factor of 3, and the derivative gain is left unchanged. Given that the closed-loop system continues to remain stable with the new gains, the steady-state error in tracking a ramp reference signal ________

Your answerChoose one option.

Remains unchanged

Decreases by a factor of 2

Decreases by a factor of 3

Decreases by a factor of 5

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The Nyquist plot of a stable open-loop system

is plotted in the frequency range

as shown. It is found to intersect a unit circle with center at the origin at the point

. The points

and

lie on

and assume values

and

. The phase margin (PM) and the gain margin (GM) of the system are ______

Diagram for Instrumentation Engineering question 43

Your answerChoose one option.

PM = 39.7° and GM = 4.76

PM = 39.7° and GM = 0.07

PM = −39.7° and GM = 4.76

PM = −39.7° and GM = 0.07

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In a unity-gain feedback control system, the plant

is controlled by a lag compensator

The slope (in dB/decade) of the asymptotic Bode magnitude plot of the loop gain at

rad/s is ______ (in integer)

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The step response of a circuit is seen to have an oscillatory behaviour at the output with oscillations dying down after some time. The correct inference(s) regarding the transfer function from input to output is/are

Your answerSelect all correct options. You can choose more than one.

that it is of at least second order.

that it has at least one pole-pair that is underdamped.

that it does not have a real pole.

that it is a first order system.

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Taking

as positive for clockwise encirclement, otherwise negative, the number of encirclements

in the Nyquist plot of

is _____.

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Consider a unity feedback configuration with a plant and a PID controller as shown in the figure.

and

with K being scalar. The closed loop is

Diagram for Instrumentation Engineering question 29

Your answerChoose one option.

only stable for

between -1 and +1

only stable for

stable for all values of

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A sinusoid

, where

is the step input, is applied to a system with transfer-function

. The amplitude of the steady state output is ____.

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GATE IN topic:control-systems PYQs

Question 15

Question 30

Question 37

Question 41

Question 43

Question 53

Question 9

Question 13

Question 29

Question 45