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Control Systems Mcqs

Q:

The Laplace transform of a parabolic signal is _______

A) 1 B) A/s³
C) A/s² D) A/s
 
Answer & Explanation Answer: A) 1

Explanation: As u(t) is a unity step function r(t)=0;t<0 and r(t)=1; t=0. The parabolic signal is a signal which has varying amplitudes and when we take Laplace Transform of that we get 1 as the answer.

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95
Q:

For a system whose transfer function is G(s) =10/s (1+s), what are the dynamic error coefficients k2 & k3 respectively as k1 is infinity?

A) 11, 10.1 B) 10.1, 11
C) 10, 11.1 D) 9, 10.1
 
Answer & Explanation Answer: C) 10, 11.1

Explanation: We should compare it with E(s)/R(s) = 1/k1+1/k2s+1/k3s². G(s) = 10/s(1+s) is compared with the above equation which is the parent equation for calculating dynamic error constants where k1 comes as infinity and K2, K3 takes the value of 10 & 11.1 respectively.

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111
Q:

The For a unity feedback system the open loop transfer function is G(s) = K(s+2)/s² (s²+7s+12). What is the value of Ka?

A) 12/k B) k/12
C) k/6 D) 6/k
 
Answer & Explanation Answer: C) k/6

Explanation: As limit s tends to zero : s²G(s) = K(s+2)/ (s²+7s+12) = k/6. Ka is the acceleration error constant which is calculated by the above method.

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38
Q:

For a unity feedback system, the open loop transfer function is G(s) = K(s+2)/s² (s²+7s+12). What is the type of system?

A) One B) Two
C) Three D) Four
 
Answer & Explanation Answer: B) Two

Explanation: As in the numerator it is mentioned K(s+2) so we got two poles in the open loop transfer function at the origin. For a given transfer function we calculate poles and zeros and the number of poles determine the type of the system.

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54
Q:

The steady state error for a unit step input is ________

A) 1/kp B) 1/(1-kp)
C) 1/2kp D) 1/(1+kp)
 
Answer & Explanation Answer: D) 1/(1+kp)

Explanation: R(s) =1/s for unit step and for the transfer function whose limit tends to zero, it is 1/1+kp. We use Laplace and Inverse Laplace Transform to calculate the same.

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49
Q:

The initial response when output is not equal to input is ______

A) Error response B) Transient response
C) Dynamic response D) Static response
 
Answer & Explanation Answer: B) Transient response

Explanation: The response is not long last lasting and real, so it is a transient response. It can’t be a static or dynamic response as the output doesn’t match the input and also there’s no chance of error response.

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44
Q:

Systems of type higher than 1 are not employed in practice.

A) True B) False
 
Answer & Explanation Answer: B) False

Explanation: Systems of type higher than 2 are not employed in practice as they’re difficult to stabilize and dynamic error increases. Systems of type 2 or lower are already stable and has less dynamic error.

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54
Q:

A unit integrator is applied to a modified system along with a ramp input. The modified value of the steady state error is 0.25. What was the initial value?

A) 0.05 B) 0.1
C) 0.15 D) 0.2
 
Answer & Explanation Answer: D) 0.2

Explanation: The integrator is similar to the phase lag systems and it is used to reduce or eliminate the steady state error and when it is cascaded with the ramp input. We know that when unit integrator is applied with a ramp input the steady state error will automatically increase but here we wanted the initial value which will be obviously less than the modified steady state error and by the same proportion.

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