18EC43
Model Question Paper-2 with effect from 2019-20 (CBCS Scheme)
USN
Fourth Semester B.E. Degree Examination
Subject CONTROL SYSTEMS
TIME: 03 Hours Max. Marks: 100
Note: 01. Answer any FIVE full questions, choosing at least ONE question from each MODULE.
02.
03.
*Bloom’s
Module -1 Taxonomy Marks
Level
Q.01 a What are the merits and demerits of Closed Loop control systems. L1 04 M
CO1
b Define control system and explain the same with an example. L1 04 M
CO1
c Find the transfer function for the given electro mechanical system shown in Fig L1, L2 12 M
1(c). CO1
dx
e b (t) = k b
dt
kb back emf constant V m−1 s−1
FIG 1(C)
OR
Q.02 a What are the classification of control system. L1 05 M
CO1
b Explain closed loop control system with an example. L1 05 M
CO1
c Find the Translational mechanical system for the Force Voltage electrical circuit L1, L2 10 M
shown in Fig 2 c. CO1
FIG 2 (C)
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Module-2
Q. 03 a V (s) L1 06 M
Find the transfer function 0 for the system shown with unity gain buffer
Vi (s) CO2
amplifier shown in Fig 3(a)
C1 C2
Vi R1 Buffer R2 V 0
Amp
FIG 3(a)
b Compare Block diagram and signal flow graph method of finding the transfer L1 04 M
function. CO2
c The system block diagram is given in Fig 3(c) below. Find L1, L2 10 M
C(s) CO2
if N(s) = 0 .
R(s)
N(S)
3
+
R(S) 10 C(S)
S+4 2
–
s + 6s
FIG 3 (c)
OR
Q.04 a What are the types of Loops and their respective loop gains in a signal flow L1 04 M
graph? CO2
b Find the transfer function by constructing a Block diagram and reducing the same L1, L2 08 M
for the circuit shown in Fig 4(b). CO2
R1 V1 C2 E0
Ei ~ R2 E0(t)
i1(t) i2(t)
Fig 4(b)
c Find the transfer function by constructing SFG and Mason’s Gain formula for the L1,L2 08 M
circuit shown in Fig 4 b. CO2
Module-3
Q. 05 a Obtain expressions for specifications namely time constant, rise time, and L1 04 M
settling time of first order system for a unit step input. CO3
b Derive an expression for C(t) of an under damped second order system for a unit L1, L2 08 M
step input. CO3
c A unity feedback system is characterized by an open loop transfer function L1,L2 08 M
K CO3
G (S) = find the value of K so that the system will have the
S ( S + 10 )
damping ratio of 0.5. for this value of K find MP, tP & tS for a unit step input.
OR
Q. 06 a Starting from the output equation C(t) derive expressions for: L1, L2 08 M
(i) Peak time (tp) (ii) Peak overshoot (Mp) CO3
of an under damped second order system subjected to unit step input.
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b K L3 08 M
A unity feedback system has G(s) = CO3
s(s + 2)(s 2 + 2s + 5)
(i) For a unit ramp input it is desired that eSS ≤ 0.2. Find K.
t2
(ii) Find eSS if r(t) = 2 + 4t +
2
c Write a short note on PID controllers. L1 04 M
CO3
Module-4
Q. 07 a Define stability and hence stable, unstable, marginally stable, and conditional L1 06 M
stability of a unity feedback system. CO4
b In a unity feedback system find the range of K for stability and K mar , ωmar with L1,L2 06 M
CO4
K
G ( s) =
s (1 + 0.4s ) (1 + 0.25s )
c Prove that part of root loci is a circle using angle condition and find the center as L2, CO4 08 M
K(s + 2)
well as radius when G(s)H(s) =
s(s + 1)
OR
Q. 08 a K L3 04 M
A – ve feedback control system is characterised by G ( s ) = CO5
s (s + α )
H(s) = 1. Find value of K and α so that Mr = 1.04 and ωr = 11.55 rad/sec
b Using RH criterion determine the stability of the system, the system is type one L1 06M
system with error constant of 10 sec−1 and poles at S = −3 and S = −6 CO4
c Find transfer function for the magnitude plot. L2,L3 10 M
CO5
Freq
Module-5
Q. 09 a Compare transfer function method and state space approach in control systems. L1,L2 04 M
CO5
b K ( s + 1) L1 10 M
Find stability and range of K using Nyquist Plot G ( s ) H ( s ) = CO5
s ( s − 1)
c Write short note on Lead, Lag, lead lag compensators. L1,CO5 06 M
OR
Q. 10 a Define state, state variable, state space. L1,CO5 04 M
b Obtain the state equations for the electrical network shown in fig 10 b. L2, L3 08 M
CO5
FIG 10 (b)
c A system is given by the following vector matrix equation write φ(t) L2,L3 08 M
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CO5
x1 = 0 1 x1 + 0 U
−4 −5 x 2 1
x 2
*Bloom’s Taxonomy Level: Indicate as L1, L2, L3, L4, etc. It is also desirable to indicate the COs and POs to be
attained by every bit of questions.
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