Dept of Aero: Unit I-Introduction PART - A (2 Marks)
Dept of Aero: Unit I-Introduction PART - A (2 Marks)
Dept of Aero: Unit I-Introduction PART - A (2 Marks)
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DEPT OF AERO
QUESTION BANK
SUBJECT CODE: EE 2365
SEM / YEAR: V/III
SUBJECT NAME: CONTROL ENGINEERING
UNIT I- INTRODUCTION
PART A (2 Marks)
1) What is control system?
In a system, when output quantity is controlled by varying the input quantity, then it is
called as control system.
7) What are the basic elements used for modeling mechanical translational systems?
1) Mass 2) Dash pot 3) Spring
8) What are the basic elements used for modeling mechanical rotational systems?
1) Moment of inertia 2) Dash pot with rotational frictional coefficient 3)Torsional spring
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13) Write force balance equation of ideal spring, ideal mass and ideal dashpot.
2 2
For Ideal mass fm = M. (d x/dt ), for ideal spring fk =k.X and for ideal dashpot fb =B. (dX/dt)
7) Determine the transfer function Y2(S)/F(S) of the system shown in fig. (16)
8) Write the differential equations governing the Mechanical rotational system shown in fig.
Draw the Torque-voltage and Torque-current electrical analogous circuits. (16)
Note: Diagrams in these above referred problems are given separately. Only the type of
the questions expected/asked in the previous year university end semester examinations
are referred here
UNIT II
OPEN AND CLOSED LOOP
SYSTEMS PART A (2 MARKS)
1) What is feedback? What type of feedback is employed in control system?
The Feedback is a control action in which the output is sampled and a proportional signal is
given back to the input for automatic correction of any changes in desired output.
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6) What is transmittance?
The transmittance is the gain acquired by the signal when it travels from one node to the
node in signal flow graph.
1. Determine the overall transfer function C(S)/R(S) for the system shown in fig. (16)
2. Obtain the closed loop transfer function C(S)/R(S) of the system whose block diagram is
shown in fig. (16)
3. For the system represented by the block diagram shown in fig. Determine C1/R1and C2/R1. (16)
4. Obtain the closed loop transfer function C(S)/R(S) of the system whose block diagram is
shown in fig. (16)
5. Find the overall gain of the system whose signal flow graph is shown in fig. (16)
6. Draw a signal flow graph and evaluate the closed loop transfer function of a system whose
block is shown in fig. (16)
Note: Diagrams in these above referred problems are given separately. Only the type of
the questions expected/asked in the previous year university end semester examinations
are referred here.
UNIT III
CHARACTERISTIC EQUATIONS AND
FUNCTIONS PART A (2 Marks)
1. What is time response?
It is the output of the closed loop system as a function of time. It is denoted by c(t).It is
given by inverse of Laplace of product of input and transfer function of the system.
-1 -1
C (t) = L {(C(s)} = L {(R(s) G(s))/ (1+G(s) H(s))}
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The transient response is the response of the system when the input changes from one state to another. The response of the system at t= is called steady state response
A parabolic signal is a signal in which the instantaneous value varies as square of the time from an initial value of zero at t=0.It is
2
mathematically represented as r (t) = A.t /2 for fort0 and r (t) =0 for t<0.
Undamped system (=0), under damped system (<1), critically damped system (=1) and over damped system (>1)
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UNIT IV
Concept of stability
PART A (2 Marks)
1. What are the two methods of designing a control system?
Base on time domain specification and based on frequency domain specifications.
The phase margin () is the amount of additional phase lag at the gain cross over frequency wgc
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21. How will you find the root locus on real axis?
To find root locus on real axis, one test point is to be chosen on real axis. If the total number
of poles and zeros on the real axis to the right of this test point is odd number, then, the test
point lies on the root locus. If it is even, then, the test point does not lie on the root locus.
22. What are asymptotes? How will you find the angle of asymptotes?
Asymptotes are straight lines which are parallel to root locus going to infinity and meet
the root locus at infinity.
Angle of asymptotes = {180 ((2.q) +1)/ (n-m)}
N= number of poles= number of zeros and q= 0, 1, 2, 3, . (n-m)
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3. Sketch the Bode plot and hence find Gain cross over frequency, Phase cross over frequency,
Gain margin and Phase margin(S) = 0.75(1+0.2S)/ S (1+0.5S) (1+0.1S) (16)
4. Sketch the Bode plot and hence find Gain cross over frequency, Phase cross over frequency,
Gain margin and Phase margin. G(S) = 10(S+3)/ S(S+2) (S2+4S+100) (16)
5. Sketch the Bode plot for the following transfer function .and find Gain cross over frequency,
Phase cross over frequency, Gain margin and Phase margin.
G(S) = 10(S+2)(S+4)/ S (S2 -3S+10) (16)
6. Construct the Bode plot for the function GH(S) =2(S+1)/ S2. Find Gain cross over frequency,
Phase cross over frequency, Gain margin and Phase margin. (16)
7. Plot the Bode diagram for the following transfer function and obtain the gain and phase cross
over frequencies. G(S) =KS2 / (1+0.2S) (1+0.02S). Determine the value of K for a gain cross over
frequency of 20 rad/sec. (16)
8. Sketch the Bode plot and hence find Gain cross over frequency, Phase cross over frequency,
Gain margin and Phase margin. G(S) = 10(1+0.1S)/ S(1+0.01S) (1+S). (16)
9. Write the short notes on correlation between the time and frequency response? (16)
10. Using Routh criterion, determine the stability of the system whose Characteristics equation
4 3 2 1
is S +8S +18S +16 +5 =0. (16)
6 5 4 3 2 1
11. F(S)=S +S -2S -3S -7S -4S -4 =0.Find the number of roots falling in the RHS plane and LHS
plane. (16)
UNIT V
SAMPLED DATA SYSTEMS
PART A (2 Marks)
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7. What are the methods available for the stability analysis of sampled data control system?
1) Jurys stability test.
2) Bilinear transformation
3) Root locus technique.
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