80+ Control System 2 Solved MCQs

1.

A control system working under unknown random action is called

A. computer control system
B. digital data system
C. stochastic control system
D. adaptive control system
Answer» C. stochastic control system
2.

The first order control system, which is is well designed, has a

A. small bandwidth
B. negative time constant
C. large negative transfer function pole
D. none of the above
Answer» C. large negative transfer function pole
3.

Zero-order hold used in practical reconstruction of continuous-time signals is mathematically represented as a weighted-sum of rectangular pulses shifted by:

A. any multiples of the sampling interval
B. integer multiples of the sampling interval
C. one sampling interval
D. 1 second intervals
Answer» B. integer multiples of the sampling interval
4.

Sampling can be done by:

A. impulse train sampling
B. natural sampling
C. flat-top sampling
D. all of the mentioned
Answer» D. all of the mentioned
5.

The first step required to convert analog signal to digital is :

A. sampling
B. holding
C. reconstruction
D. quantization
Answer» A. sampling
6.

Sampling is necessary :

A. in complex control systems
B. where high accuracy is required
C. non automated control systems
D. automated control system
Answer» B. where high accuracy is required
7.

_______________ is a sampling pattern which is repeated periodically

A. single order sampling
B. multi order sampling
C. zero order sampling
D. unordered sampling
Answer» B. multi order sampling
8.

Aliasing is caused when:

A. sampling frequency must be equal to the message signal
B. sampling frequency must be greater to the message signal
C. sampling frequency must be less to the message signal
D. sampling frequency must be greater than or equal to the message signal
Answer» C. sampling frequency must be less to the message signal
9.

The signal is reconstructed back with the help of

A. zero order hold circuits
B. extrapolations
C. signal is reconstructed with zero order holds and extrapolations
D. signal is not reconstructed
Answer» C. signal is reconstructed with zero order holds and extrapolations
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
Answer» C. stochastic control system
11.

Zero initial condition for a system means

A. input reference signal is zero
B. zero stored energy
C. no initial movement of moving parts
D. system is at rest and no energy is stored in any of its components
Answer» D. system is at rest and no energy is stored in any of its components
12.

The first order control system ,which is well designed has a

A. small bandwidth
B. negative time constant
C. large negative transfer function pole
D. none of the above
Answer» C. large negative transfer function pole
13.

A zero order hold is used with sampled data system to

A. make it critically damped
B. reconstruct the sampled signal
C. improve the stability of the system
D. convert it to a continuous system
Answer» B. reconstruct the sampled signal
14.

A controller is basically a ---

A. sensor
B. comparator
C. amplifier
D. clipper
Answer» B. comparator
15.

Z and Laplace transform are related by:

A. s = ln z
B. s =ln z/t
C. s =z
D. s= t/ln z
Answer» B. s =ln z/t
16.

What is the z-transform of the signal x[n] = an u(n)?

A. x(z) =1/z-1
B. x(z) = 1/1-z
C. x(z) = z/z-a
D. x(z) = 1/z-a
Answer» C. x(z) = z/z-a
17.

Which one of the following rules determine the mapping of s-plane to z-plane?

A. right side of the s-plane maps into outside of the unit circle in z-plane
B. left half of s-plane maps into inside of the unit circle
C. imaginary axis in s-plane maps into the circumference of the unit circle
D. all of the mentioned
Answer» D. all of the mentioned
18.

Assertion (A): The z-transform of the output of the sampler is given by the series. Reason (R): The relationship is the result of the application of z = e-sT, where T stands for the time gap between the samples.

A. both a and r are true and r is correct explanation of a
B. both a and r are true but r is not correct explanation of a
C. a is true but r is false
D. a is false but r is true
Answer» C. a is true but r is false
19.

Inverse z-transform of the system can be calculated using:

A. partial fraction method
B. long division method
C. basic formula of the z-transform
D. all of the mentioned
Answer» D. all of the mentioned
20.

If the z transform of x(n) is X(z) =z(8z-7)/4z2 -7z+3, then the final value theorem is :

A. 1
B. 2
C.
D. 0
Answer» A. 1
21.

Difference equation model results in:

A. sampled-data systems
B. numerical analysis of continuous time systems
C. continuous time feedback systems
D. both a & b
Answer» D. both a & b
22.

Which of the following is an advantage of Laplace transform method

A. it gives solution in frequency domain only
B. it gives total solution more systematically
C. initial conditions are incorporated in the very first step
D. both b & c
Answer» D. both b & c
23.

Analysis of control system by Laplace transform technique is not possible for

A. discrete time systems
B. linear systems
C. time invarient systems
D. unstable continuous time systems
Answer» A. discrete time systems
24.

Z-transform is used in:

A. continuous optimal control problem
B. discrete optimal problem
C. control systems
D. none of the mentione
Answer» B. discrete optimal problem
25.

Unit step response of the system described by the equation y(n) +y(n-1) =x(n) is:

A. z2/(z+1)(z-1)
B. z/(z+1)(z-1)
C. z+1/z-1
D. z(z-1)/z+1
Answer» A. z2/(z+1)(z-1)
26.

Difference equation model results in:

A. sampled-data systems
B. numerical analysis of continuous time systems
C. continuous time feedback systems
D. both a and b
Answer» D. both a and b
27.

For relative stability of the system which of the following is sufficient?

A. gain margin
B. phase margin
C. both a and b
D. magnitude
Answer» C. both a and b
28.

Stability of a system implies that :

A. small changes in the system input does not result in large change in system output
B. small changes in the system parameters does not result in large change in system output
C. small changes in the initial conditions does not result in large change in system output
D. small changes in the initial conditions result in large change in system output
Answer» A. small changes in the system input does not result in large change in system output
29.

Linear mathematical model applies to :

A. linear systems
B. stable systems
C. unstable systems
D. all of the mentioned
Answer» B. stable systems
30.

With feedback _____ reduces.

A. system stability
B. system gain
C. system stability and gain
D. damping
Answer» B. system gain
31.

Asymptotic stability is concerned with:

A. a system under influence of input
B. a system not under influence of input
C. a system under influence of output
D. a system not under influence of ou
Answer» B. a system not under influence of input
32.

A linear time invariant system is stable if :

A. system in excited by the bounded input, the output is also bounded
B. in the absence of input output tends zero
C. both a and b
D. system in excited by the bounded input, the output is not bounded
Answer» C. both a and b
33.

If a system is given unbounded input then the system is:

A. stable
B. unstable
C. not defined
D. linear
Answer» C. not defined
34.

If the impulse response in absolutely integrable then the system is :

A. absolutely stable
B. unstable
C. linear
D. stable
Answer» A. absolutely stable
35.

If root of the characteristic equation has positive real part the system is :

A. stable
B. unstable
C. marginally stable
D. linear
Answer» B. unstable
36.

The use of sampled data control system are:

A. for using analog components as the part of the control loop
B. for time division of control components
C. whenever a transmission channel forms a part of closed loop
D. none of the mentioned
Answer» C. whenever a transmission channel forms a part of closed loop
37.

Jury’s test determines whether the roots of a polynomial lie:

A. close to unit circle
B. within the unit circle
C. outside the unit circle
D. on the unit circle
Answer» B. within the unit circle
38.

The transformation technique in which there is one to one mapping from s-domain to z-domain is

A. approximation of derivatives
B. impulse invariance method
C. bilinear transformation method
D. backward difference for the derivative
Answer» C. bilinear transformation method
39.

Parallel form of realisation is done in

A. high speed filtering applications
B. low speed filtering applications
C. both a and b
D. none of the above
Answer» A. high speed filtering applications
40.

In cascade form of realization, how many bits should be used to represent the FIR filter coefficients in order to avoid the quantization effect on filter coefficients?

A. 5 to 10
B. 12 to 14
C. 20 to 24
D. 28 to 40
Answer» B. 12 to 14
41.

How is the sampling rate conversion achieved by factor I/D?

A. by increase in the sampling rate with (i)
B. by filtering the sequence to remove unwanted images of spectra of original signal
C. by decimation of filtered signal with factor d
D. all of above
Answer» D. all of above
42.

In the cascaded form of realisation, the polynomials are factored into

A. product of 1st-order and 2nd-order polynomials
B. product of 2nd-order and 3rd-order polynomials
C. sum of 1st-order and 2nd-order polynomials
D. sum of 2nd-order and 3rd-order polynomials
Answer» A. product of 1st-order and 2nd-order polynomials
43.

Open loop transfer function of a system having one zero with a positive real value is called.

A. zero phase function
B. negative phase function
C. positive phase function
D. non-minimum phase function
Answer» D. non-minimum phase function
44.

Consider the function F (s)= 5/s(s2+3s+2), the initial value of f(t) is:

A. 5
B. 5/2
C. 5/3
D. 0
Answer» D. 0
45.

In a closed loop for which the output is the speed of the motor, the output rate control can be used to:

A. limit the speed of the motor
B. limit the torque output of the motor
C. reduce the damping of the system
D. limit the acceleration of the motor
Answer» A. limit the speed of the motor
46.

The transfer function of any stable system which has no zeros or poles in the right half of the s-plane is said to be:

A. minimum phase transfer function
B. non-minimum phase transfer function
C. minimum phase frequency response function
D. minimum gain transfer function
Answer» A. minimum phase transfer function
47.

State model representation is possible using _________

A. physical variables
B. phase variables
C. canonical state variables
D. all of the above
Answer» D. all of the above
48.

Conventional control theory is applicable to ______ systems

A. siso
B. mimo
C. time varying
D. non-linear
Answer» A. siso
49.

The transfer function for the state representation of the continuous time LTI system: dq(t)/dt=Aq(t)+Bx(t) Y(t)=Cq(t)+Dx(t) is given by

A. c(si-a)-1b+d
B. b(si-a)-1b+d
C. c(si-a)-1b+a
D. d(si-a)-1b+c
Answer» A. c(si-a)-1b+d
50.

The system which works on the initial condition without any input applied to it is called as :

A. homogeneous system
B. non homogeneous system
C. linear system
D. non linear system
Answer» A. homogeneous system
51.

The transfer function of a LTI system is given as 1/(s+1). What is the steady-state value of the unit-impulse response?

A. 0
B. 1
C. 2
D. infinite
Answer» A. 0
52.

The values of the characteristic equation is given by:

A. eigen values
B. state matrix
C. eigen vector
D. none of the mentioned
Answer» A. eigen values
53.

The state variable representation is preferred

A. to increase the sensitivity to the plant parameter variations
B. to reduce the sensitivity to the plant parameter variations
C. to make a plant simple and to control the transient response
D. none of the above
Answer» C. to make a plant simple and to control the transient response
54.

With the knowledge of state space representation the transfer function of the system

A. can be determined partly
B. can be determined completely
C. cannot be determined
D. none of the above
Answer» B. can be determined completely
55.

Which among the following are the interconnected units of state diagram representation?

A. scalars
B. adders
C. integrators
D. all of the above
Answer» D. all of the above
56.

Which among the following controls the speed of D.C. motor?

A. galvanometer
B. gauss meter
C. potentiometer
D. tachometer
Answer» D. tachometer
57.

State model representation is possible using _________

A. . physical variables
B. . phase variables
C. canonical state variables
D. all of the above
Answer» D. all of the above
58.

Which among the following constitute the state model of a system in addition to state equations?

A. . input equations
B. . output equations
C. state trajectory
D. state vector
Answer» B. . output equations
59.

Which among the following plays a crucial role in determining the state of dynamic system?

A. . state variables
B. state vector
C. state space
D. state scalar
Answer» A. . state variables
60.

What is Eigen value?

A. a vector obtained from the coordinates
B. a matrix determined from the algebraic equations
C. a scalar associated with a given linear transformation
D. it is the inverse of the transform
Answer» C. a scalar associated with a given linear transformation
61.

Let us consider a 3×3 matrix A with Eigen values of λ1, λ2, λ3 and the Eigen values of A-1 are?

A. λ1, λ2, λ3
B. 1/λ1,1/λ2,1/λ3
C. -λ1, -λ2, -λ3
D. λ1, 0, 0
Answer» B. 1/λ1,1/λ2,1/λ3
62.

The Eigen values of a 3×3 matrix are λ1, λ2, λ3 then the Eigen values of a matrix A3 are __________

A. λ1, λ2, λ3
B. 1/λ1,1/λ2,1/λ3
C. λ31,λ32,λ33
D. 1, 1, 1
Answer» C. λ31,λ32,λ33
63.

State space analysis is applicable even if the initial conditions are _____

A. zero
B. non-zero
C. equal
D. not equal
Answer» B. non-zero
64.

According to the property of state transition method, e0 is equal to _____

A. i
B. a
C. e-at
D. -eat
Answer» C. e-at
65.

Which mechanism in control engineering implies an ability to measure the state by taking measurements at output?

A. controllability
B. observability
C. differentiability
D. adaptability
Answer» B. observability
66.

State model representation is possible using _________

A. physical variables
B. phase variables
C. canonical state variables
D. all of the mentioned
Answer» D. all of the mentioned
67.

Which among the following constitute the state model of a system in addition to state equations?

A. input equations
B. output equations
C. state trajectory
D. state vector
Answer» B. output equations
68.

Which among the following are the interconnected units of state diagram representation?

A. scalars
B. adders
C. integrator
D. all of the mentioned
Answer» D. all of the mentioned
69.

Which among the following is a unique model of a system?

A. transfer function
B. state variable
C. block diagram
D. signal flow graphs
Answer» A. transfer function
70.

State model is generally not suitable for measuring:

A. investigation of system properties
B. evaluation of time response
C. real variables
D. both a and b
Answer» D. both a and b
71.

______________ are the techniques for converting general state models into canonical one.

A. observable
B. controllable
C. diagoanlization
D. cannonical
Answer» C. diagoanlization
72.

The diagonalizing matrix is also known as:

A. eigen matrix
B. modal matrix
C. constant matrix
D. state matrix
Answer» B. modal matrix
73.

A system is said to be_____________ if it is possible to transfer the system state from any initial state to any desired state in finite interval of time.

A. controllable
B. observable
C. cannot be determined
D. controllable and observable
Answer» A. controllable
74.

A system is said to be_________________ if every state can be completely identified by measurements of the outputs at the finite time interval.

A. controllable
B. observable
C. cannot be determined
D. controllable and observable
Answer» B. observable
75.

Kalman’s test is for :

A. observability
B. controllability
C. optimality
D. observability and controllability
Answer» D. observability and controllability
76.

Consider a system if represented by state space equation and x1 (t) =x2 (t), then the system is:

A. controllable
B. uncontrollable
C. observable
D. unstable
Answer» B. uncontrollable
77.

A transfer function of the system does not have pole-zero cancellation? Which of the following statements is true?

A. system is neither controllable nor observable
B. system is completely controllable and observable
C. system is observable but uncontrollable
D. system is controllable and unobservable
Answer» B. system is completely controllable and observable
78.

The impulse response of a linear LTI system is given as g (t) = e(-t)The transfer function of the system is equal to:

A. 1/s
B. 1/s(s+1)
C. 1/(s+1)
D. s/(s+1)
Answer» C. 1/(s+1)
79.

An oberser or program that that estimates less than n state variables, where n is dimension of stage vector is called

A. reduced order state observer
B. simply a reduced order observer
C. full observer
D. state observer
Answer» A. reduced order state observer
80.

Gilbert's test is used to check

A. controllabilty
B. observability
C. observer
D. controlability & observability
Answer» D. controlability & observability
81.

The necessary and sufficient condition for the system to be completely state controllable is that therank of the composite matrix QC is

A. 1
B. n
C. 2
D. 3
Answer» B. n
82.

In control system an error detector

A. detects error and signal out an alarm
B. detects error of the system
C. produces an error signal as actual difference of value and desired value of output
D. any of the above
Answer» B. detects error of the system
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