Control Systems

Question 1

A unity feedback control system has a G value of 40/s(s + 20). The closed-loop response is very slow, and the tachometer feedback is considered to improve the response. If the tachometer response has a transfer function ks, what is the value of k necessary to get a damping ratio of 0.707?

A. 0.45

B. -0.45

C. 0.27

D. -0.27

Answer 1

Correct Option: D

Question 2

If there is a third-order all-pole system, what would the slope be of the Bode plot for high frequencies?

A. 60 dB/decade

B. 30 dB/decade

C. -30 dB/decade

D. -60 dB/decade

Answer 2

Correct Option: D
Solution:
When constructing a Bode plot, each pole gives the slope of the plot a -20-dB/decade slope. These slopes are additive.

Each zero gives the slope +20 dB/decade.

Given that there are no zeros and three poles, there would be a -60 dB/decade slope at high frequencies (the effects of all the poles are in place).

Question 3

What are the methods of specifying the performance of control systems?

A. Peak overshoot
B. Setting time
C. Gain margin
D. All the above

Answer 3

D. All the above

Question 4

Which of the following plots is preferred over bode plots?

A. Polar plots
B. Nicholas chart
C. Transport lay
D. Bode plots

Answer 4

A. Polar plots

Question 5

Which of the following is a relaxed-linear system bounded with finite input results that are bounded in finite output

A. BIBO stability
B. Absolute stable
C. Relative stable
D. Marginal table

Answer 5

A. BIBO stability

Question 6

Which of the following is used to determine the condition of stability foe linear feedback control system?

A. Root locus
B. Gain margin
C. Limited stable system
D. Root stability criterion

Answer 6

D. Root stability criterion

Question 7

What is the amount of gain in decibel to be increased in the loop before the closed-loop system reaches stability?

A. Gain margin
B. State variables
C. State vector
D. State space

Answer 7

A. Gain margin

Question 8

The changes in the parameters due to environmental changes and disturbances are referred to as:

A. Stability
B. Sensitivity control
C. Parameters
C. Parameter variations

Answer 8

C. Parameter variations

Question 9

How is the velocity coefficient determined?

A. Type 0
B. Type 2
C. Type 1
D. Type 3

Answer 9

C. Type 1

Question 10

Which of the following points occurs in the multiple roots of the characteristic equation?

A. Multiple points
B. Breakaway points
C. Characteristic points
D. State space

Answer 10

B. Breakaway points

Question 11

Which of the following techniques provides a graphical method of plotting the locus in the s-plane?

A. Bode plots
B. Root locus
C. State variables
D. Stability

Answer 11

B. Root locus

Question 12

Which one the following has a constant amplitude oscillator for output?

A. Low-level oscillations
B. Gain margin
C. Limited stable system
D. Stability

Answer 12

C. Limited stable system

Question 13

Which one of the following is obtained from a system’s variables and it derivatives?

A. State variables
B. Phase variables
C. Stable system
D. Steady state response

Answer 13

B. Phase variables

Question 14

What are the classifications of stability?

A. Absolute stable
B. Condition stable
C. Marginal stable
D. All of the above

Answer 14

D. All of the above

Question 15

What is the necessary condition for stability in all the coefficients of the characteristic polynomial?

A. Positive
B. Negative
C. Zero
D. Parameters

Answer 15

A. Positive

Question 16

How to represent the gain cross over frequencies

A. Double
B. Unity
C. Gauge
D. Phase

Answer 16

B. Unity

Question 17

Which type of stable system is used for a bounded input?

A. Limited stable system
B. Stability
C. Marginal stability system
D. System state

Answer 17

C

Question 18

Nyquist stability criterion is based:

A. Cauchy’s residue theorem
B. principle of argument
C. loop theorem
D. gain margin

Answer 18

A. Cauchy’s residue theorem

Question 19

Which of the following are time domain specifications?

A. Delay time
B. Rise time
C. Peak time
D. All the above

Answer 19

D. All the above

Question 20

The ___________ is used to represent a logarithmic plot which consist of two graphs:

A. decade plot
B. bode plot
C. polar plot
D. pure delay

Answer 20

B. bode plot

Question 21

Give the expression for total time response C(t)?

A. C(t) = Ct(t)
B. C(t) = C(t) - css(t)
C. C(t) = css(t) - Ct(t)
B. C(t) = css(t) + Ct(t)

Answer 21

B. C(t) = css(t) + Ct(t)

Question 22

What type of controller is used to increased the damping factor of the dominant poles?

A. PID controller
B. PD controller
C. PI controller
D. Derivative controller

Answer 22

A. PID controller

Question 23

Which one of the following breaks the real axis to enter into the complex plane?

A. Bode plots
B. Load cell calibration
C. Root locus
D. Polar plot

Answer 23

C. Root locus

Question 24

What exists when a closed sequence of cause and effect relations exist between an available system?

A. Open loop system
B. Feedback
C. Feedforward
D. Close loop system

Answer 24

B. Feedback