Control Systems Questions & Answers

 Control Systems Questions & Answers

1. In case of type-1 system steady state acceleration is
a) unity
b) infinity
c) zero
d) 10
Answer: infinity
2. Which of the following devices is used for conversion of co-ordinates ?
a) Microsyn
b) Selsyn
c) Synchro-resolver
d) Synchro-transformer
Answer: Synchro-resolver
3. Which of the following is the best method for determining the stability and transient response ?
a) Root locus
b) Bode plot
c) Nyquist plot
d) None of the above
Answer: Root locus
4. An increase in gain, in most systems, leads to
a) smaller damping ratio
b) larger damping ratio
c) constant damping ratio
d) none of the above
Answer: smaller damping ratio
5. A conditionally stable system exhibits poor stability at
a) low frequencies
b) reduced values of open loop gain
c) increased values of open loop gain
d) none of the above
Answer: reduced values of open loop gain
6. Which of the following is the non-linearity caused by servomotor ?
a) Static friction
b) Backlash
c) Saturation
d) None of the above
Answer: Saturation
7. The type 1 system has _________ at the origin.
a) no pole
b) net pole
c) simple pole
d) two poles
Answer: simple pole
8. The type 2 system has    at the origin.
a) no net pole
b) net pole
c) simple pole
d) two poles
Answer: two poles
9. The position and velocity errors of a type-2 system are
a) constant, constant
b) constant, infinity
c) zero, constant
d) zero, zero
Answer: zero, constant
10. Velocity error constant of a system is measured when the input to the system is unit ___________ function.
a) parabolic
b) ramp
c) impulse
d) step
Answer: ramp
11. ___ can be extended to systems which are time-varying ?
a) Bode-Nyquist stability methods
b) Transfer functions
c) Root locus design
d) State model representatives
Answer: State model representatives
12. If a step function is applied to the input of a system and the output remains below a certain level for all the time, the system is
a) not necessarily stable
b) stable
c) unstable
d) always unstable
Answer: not necessarily stable
13. The frequency and time domain are related through which of the following?
a) Laplace Transform and Fourier Integral
b) Laplace Transform
c) Fourier Integral
d) Either (b) or (c)
Answer: Laplace Transform and Fourier Integral
14. Phase margin of a system is used to specify which of the following ?
a) Frequency response
b) Absolute stability
c) Relative stability
d) Time response
Answer: Relative stability
15. Addition of zeros in transfer function causes which of the following ?
a) Lead-compensation
b) Lag-compensation
c) Lead-lag compensation
d) None of the above
Answer: Lag-compensation
16. In order to increase the damping of a badly underdamped system which of following compensators may be used ?
a) Phase-lead
b) Phase-lag
c) Both (a) and (b)
d) Either (a) and (b)
Answer: Phase-lead
17. The phase lag produced by transportation relays
a) is independent of frequency
b) is inverseh’proportional to frequency
c) increases linearly with frequency
d) decreases linearly with frequency
Answer: increases linearly with frequency
18. In a stable control system saturation can cause which of the following ?
a) Low-level oscillations
b) High-level oscillations
c) Conditional stability
d) Overdamping
Answer: Low-level oscillations
19. Which of the following can be measured by the use of a tacho-generator ?
a) Acceleration
b) Speed
c) Speed and acceleration
d) Displacement
Answer: Speed
20. ___________ technique gives quick transient and stability response
a) Root locus
b) Bode
c) Nyquist
d) Nichols
Answer: Root locus
21. _________ is not a final control element.
a) Control valve
b) Potentiometer
c) Electro-pneumatic converter
d) Servomotor
Answer: Potentiometer
22. In pneumatic control systems the control valve used as final control element converts
a) pressure signal to electric signal
b) pressure signal to position change
c) electric signal to pressure signal
d) position change to pressure signal
Answer: pressure signal to position change
23. Spring constant in force-voltage analogy is analogous to
a) capacitance
b) reciprocal of capacitance
c) current
d) resistance
Answer: reciprocal of capacitance
24. Pressure error can be measured by which of the following ?
a) Differential bellows and straingauge
b) Selsyn
c) Strain gauge
d) Strain gauge and potentiometer
Answer: Differential bellows and straingauge
25. The effect of error damping is to
a) provide larger settling lime
b) delay the response
c) reduce steady state error
d) none of the above
Answer: reduce steady state error
26. Which of the following is the definition of proportional band of a controller ?
a) The range of air output as measured variable varies from maximum to minimum
b) The range of measured variables from set value
c) The range of measured variables through which the air output chan¬ges from maximum to minimum
d) None of the above
Answer: The range of measured variables through which the air output chan¬ges from maximum to minimum
27. A phase lag lead network introduces in the output
a) lag at all frequencies
b) lag at high frequencies and lead at low frequencies
c) lag at low frequencies and lead at high frequencies
d) none of the above
Answer: lag at low frequencies and lead at high frequencies
28. ______ technique is not applicable to nonlinear system ?
a) Nyquist Criterion
b) Quasi linearization
c) Functional analysis
d) Phase-plane representation
Answer: Nyquist Criterion
29. Static error co-efficients are used as a measure of the effectiveness of closed loop systems for specified     ________ input signal.
a) acceleration
b) velocity
c) position
d) all of the above
Answer: all of the above
30. The type 0 system has ________ at the origin.
a) no pole
b) net pole
c) simple pole
d) two poles
Answer: no pole


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