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Seat No.: Enrolment
GUJARAT TECHNOLOGICAL UNIVERSITY
PDDC- SEMESTER-III EXAMINATION SUMMER 2017
Subject Code: X30903 Date:31/05/2017
Subject Name: Control Theory
Time: 02:30 PM to 05:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
Q.1

Compare open loop and close loop control system
07

Explain force to current analogy with proper example.
07
Q.2

Using block diagram reduction techniques find the close loop transfer function of the system given in fig.1
07

Using Mason's gain formula, find the gain of following signal flow graph shown in fig.2
07
OR

Determine the Transfer Function of the network shown in fig.3
07
Q.3

Describe liquid level system and derive transfer function of liquid level system with interaction.
07

Find out the stability of the system by Routh criterion if the characteristic equation is given by, S4 S3 2S2 2S 3 0.
07
OR
Q.3

Using suitable diagram derive the transfer function of Thermometer placed in water bath as a Thermal system.
07

Define: Delay time, rise time, pick time, settling time Peak Overshoot Absolute stability, Relative stability.
07
Q.4

Plot the root locus for the unity feedback system with
.
07

Explain the advantages of state space over classical approaches also define State variable, State-space state-vector.
07
OR
Q.4

Explain procedure to obtain asymptotes centroid of asymptotes and breakaway points in root locus. Also explain significance of the root locus.
07

Derive the expression for unit step response for second order control system for
07
Q.5

Define and explain following terms with respect to frequency response
(1)Gain Margin Phase Margin Gain cross-over frequency Phase cross-over Frequency.
07

Using Nyquist plot, comment on the stability of the following system,
.
07
OR
Q.5

Explain the general steps for solving Bode Plot.
07

Sketch the polar plot of the transfer function,
.
07
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