# Multiple choice question for engineering

## Set 1

1. A control system in which the control action is somehow dependent on the output is known as

a) Closed loop system

b) Semi closed loop system

c) Open system

d) Non feedback control system

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2. In closed loop control system, with positive value of feedback gain the overall gain of the system will

a) Decrease

b) Increase

c) Be unaffected

d) Exponentially increase

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3. Which of the following is an open loop control system?

a) Field controlled D.C. motor

b) Ward Leonard control

c) Metadyne

d) Stroboscope

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4. Which of the following statements is not necessarily correct for open control system?

a) Input command is the sole factor responsible for providing the control action

b) Presence of non-linearities causes malfunctioning

c) Less expensive

d) Generally free from problems of non-linearities

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5. In open loop system

a) The control action depends on the size of the system

b) The control action depends on system variables

c) The control action depends on the input signal

d) The control action is independent of the output

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6. ___________has tendency to oscillate.

a) Open loop system

b) Closed loop system

c) Open and closed loop systems have tendency to oscillate

d) No Systems have tendency to oscillate

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7. A good control system has all the following features except

a) Good stability

b) Slow response

c) Good accuracy

d) Sufficient power handling capacity

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8. A car is running at a constant speed of 50 km/h, which of the following is the feedback element for the driver?

a) Clutch

b) Eyes

c) Needle of the speedometer

d) Steering wheel

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9. The initial response when the output is not equal to input is called

a) Transient response

b) Error response

c) Dynamic response

d) All of the mentioned

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10. A control system working under unknown random actions is called

a) Computer control system

b) Digital data system

c) Stochastic control system

d) Adaptive control system

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## Set 2

1. The impulse response of a LTI system is a unit step function, then the corresponding transfer function is

a) 1/s

b) 1/s^{2}

c) 1

d) s

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2. For a type one system, the steady – state error due to step input is equal to

a) Infinite

b) Zero

c) 0.25

d) 0.5

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3. The equation 2s^{4}+s^{3}+3s^{2}+5s+10=0 has roots in the left half of s–plane:

a) One

b) Two

c) Three

d) Four

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4. If the Nyquist plot of the loop transfer function G (s)H (s) of a closed-loop system encloses the (1, j0) point in the G (s)H (s) plane, the gain margin of the system is

a) Zero

b) Greater than zero

c) Less than zero

d) Infinity

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5. Consider the function F (s) =5/s (s^{2}+s+2) , where F (s) is the Laplace transform f (t). Then the final value theorem is equal to

a) 5

b) 5/2

c) Zero

d) Infinity

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6. The transfer function of a phase-lead controller is given by

a) (1+aTs)/(1+Ts) , a>1 T>0

b) (1+aTs)/(1+Ts) , a<1 T>0

c) (1-aTs)/(1+Ts) , a>1 T>0

d) (1±Ts)/(1+Ts) , a<1 T>0

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7. If the system matrix of a linear time invariant continuous system is given by

Its characteristic equation is given by:

a) s^{2}+5s+3=0

b) s^{2}-3s-5=0

c) s^{2}+3s+5=0

d) s^{2}+s+2=0

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8. Given a unity feedback control system with G (s) = K/s(s+4), the value of K for which the damping ratio is 0.5.

a) 1

b) 16

c) 64

d) 32

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9. The LVDT is used in the measurement of:

a) Displacement

b) Acceleration

c) Velocity

d) Humidity

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10. A system with gain margin close to unity and phase margin close to zero is :

a) Highly stable

b) Oscillatory

c) Relatively stable

d) Unstable

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## Set 3

1. The output of the system is considered near :

a) 1

b) 2

c) 3

d) 0

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2. A performance index written in terms of :

a) 1 variable

b) 2 variable

c) 3 variable

d) 5 variable

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3. Matrix Q is :

a) Positive semi definite symmetric matrix

b) Positive definite non-symmetric matrix

c) Negative definite symmetric matrix

d) Negative definite non-symmetric matrix

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4. Matrix R is :

a) Positive semi definite symmetric matrix

b) Positive definite non-symmetric matrix

c) Negative definite symmetric matrix

d) Negative definite non-symmetric matrix

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5. The major requirement of making the output of the system small in output regulator problem is :

a) The system must be controllable

b) The system must be stable

c) The system must be observable

d) The system must be LTI

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6. Minimum principle was given by:

a) Pontryagin

b) Hamiltonian

c) Bellman

d) Jacobi

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7. Dynamic programming is developed by:

a) Pontryagin

b) Hamiltonian

c) Bellman

d) Jacobi

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8. The performance index is reduced by:

a) State variable constraint

b) Input constraint

c) Control function minimization

d) Control function constraint

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9. Minimum principle is based on :

a) Concepts of calculus of variations

b) Principle of calculus

c) Principle of invariant imbedding

d) Principle of optimality

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10. Dynamic programming is based on :

a) Principle of calculus

b) Principle of invariant imbedding

c) Principle of optimality

d) All of the mentioned

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## Set 4

1. The main step for solving the optimal control problem:

a) Transfer function of system which is optimal with respect to the given performance criterion

b) Compensators for the system

c) Minimizing the quadratic function

d) All of the mentioned

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2. For minimizing the transfer function the condition is :

a) Second differentiation of the function must be zero

b) Second differentiation of the function must be positive

c) Second differentiation of the function must be negative

d) Second differentiation of the function must be complex

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3. For the stability in optimal control poles of the transfer function must be :

a) Located on the right half of s plane

b) Left half of s plane

c) On the s plane

d) None of the mentioned

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4. The method of choosing compensator is the configuration must be:

a) Forward path

b) Cascade and feedback compensation

c) Feed forward configuration

d) All of the mentioned

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5. When some of the states are inaccessible, then we may set the feedback coefficients equal to zero.

a) True

b) False

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6. Z-transform is used in:

a) Continuous optimal control problem

b) Discrete optimal problem

c) Control systems

d) None of the mentioned

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7. For the stable system in discrete optimal control systems:

a) Poles must lie outside the unit circle

b) Poles must lie within the unit circle

c) Poles must be on the unit circle

d) Pole must be in infinity

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8. The special case of the tracking problem with input equal to zero:

a) Free response

b) Regulator problem

c) Forced response

d) Output regulator problem

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9. The primary objective of the output regulator problem is to damp out:

a) Initial conditions quickly

b) Reducing the effect of excessive oscillations

c) Reducing the effect of excessive overshoot

d) All of the mentioned

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10. The limitation of the transfer function approach are:

a) The spectral factorization becomes quite complex

b) It is restricted to the systems with all performance index

c) Multi input and multi output systems are not obvious

d) It is useful for time varying and linear systems

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## Set 5

1. For output regulator problem in performance index the parameter which is set to zero:

a) Input vector

b) Output vector

c) Control vector

d) State vector

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2. In tracking problem the parameter reduced is :

a) Error

b) Output

c) Input

d) State

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3. Riccati equation is formed by using:

a) Output regulator problem

b) Finite state regulator problem

c) Infinite state regulator problem

d) Tracking problem

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4. The value of K must further follow the following constraint that the closed loop system must be:

a) Asymptotically stable

b) Stable

c) Marginally stable

d) Conditionally stable

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5. For suboptimal control the value of R is assumed to be:

a) Positive definite

b) Non-positive definite

c) Negative

d) Complex

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6. Which one of the following compensation is required for improving the transient response of the system?

a) Phase lead compensation

b) Phase lag compensation

c) Gain compensation

d) Both phase lag compensation and gain compensation

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7. Pneumatic controller

a) Flexible operation

b) High torque high speed operation

c) Fire and explosion proof operation

d) No leakage

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8. Hydraulic controller:

a) Flexible operation

b) High torque high speed operation

c) Fire and explosion proof operation

d) No leakage

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9. Electronic Controller:

a) Flexible operation

b) High torque high speed operation

c) Fire and explosion proof operation

d) No leakage

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10. Which one of the following statement is correct?

A plant controlled by a proportional controller. If a time delay element is introduced in the loop its:

a) Phase margin remains the same

b) Phase margin increases

c) Phase margin decreases

d) Gain margin increases