GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER-1V (NEW) EXAMINATION - WINTER 2018
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Subject Code:2142003 Date:01/12/2018
Subject Name:Control Theory
Time: 02:30 PM TO 05:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
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2. Make suitable assumptions wherever necessary.3. Figures to the right indicate full marks.
Q.1 (a) Describe any three block diagram reduction techniques. 03
(b) Explain Mason’s gain formula. 04
(c) Using Routh’s criterion check the stability of a system whose characteristic 07
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equation is given by s6+ 3s5+ 4s4+ 6s3+ 5s2+ 3s +2=0.Q.2 (a) Explain, How the gain and phase margin are obtained from Nyquist plots? 03
(b) Explain force voltage analogy with proper example. 04
(c) Explain standard Test signals & derive equation of steady state error. 07
OR
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(c) Explain following terms with necessary diagrams. (1) Delay Time (2) Rise Time (3) 07Peak Time (4) Steady state error (5) Settling Time.
Q.3 (a) Derive Correlation Between Transfer Functions and State-Space Equations. 03
(b) Determine the transfer function of system if impulse response of system is 04
e2tsin 3t (c) For the given mechanical system Write down differential equations, mechanical 07
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circuit diagram and obtain force-voltage analogy.OR
Q.3 (a) Define thermal resistance and thermal capacitance. Also derive the transfer function 03
of Thermometer placed in water bath as a Thermal system.
(b) Write short notes on open loop control systems and closed loop control systems. 04
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Discuss their advantages and disadvantages.(c) Obtain a state space and out-put equation for the system defined by 07
Y(s) 2s3+s2+s+2
U(s) s3+4s2+5s+2
Q.4 (a) Derive the expression for time response of first order control system subjected to 03
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unit step input.(b) Using suitable diagram derive the transfer function of liquid level system with 04
interaction.
(c) Draw root locus where G(s)H(s) = K(s +0.1) / (s2 +5s +0.8). Determine range of K for system 07
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stability. Also write the matlab code for the same.OR
Q.4 (a) What do you understand by absolute stability and relative stability? Which method 03
indicates what type of stability?
(b) Comment on the effect of derivative control on damping ratio, rise time, peak 04
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time and maximum overshoot.(c) A second order system is represented by the transfer function given below 07
C(s) 1
R(s) Js2+Fs+K
A step input of 10Nm is applied to the system and the test results are:
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a) Maximum overshoot =6%b) Time at peak overshoot = 1 sec
c) The steady value of the output is 0.5 radians
Determine the values of J,F.K
Q.5 (a) Mention the advantages of frequency domain analysis. 03
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(b) Determine the relation between the phase margin and damping ratio for an 04underdamped second-order system.
(c) Using Nyquist plot, comment on the stability of the following system. 07
G(s)H(s) = 2.2 / (s(s+1)(s2+2s+2))
OR
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Q.5 (a) How will you obtain the transfer function from Bode magnitude plot? 03
(b) State space and out-put equation for the system.defined by 04
Obtain the transfer function of the system.
(c) Sketch the Bode plot and determine the gain margin and phase margin for the 07
given unity feedback control.system.
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G(s) = 10 / (s(s+1)(s+5))--- Content provided by FirstRanker.com ---
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