JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech III Year CONTROL SYSTEMS ENGINEERING Previous Question Paper (August/September - 2024 - R13)
Note: i) Question paper consists of Part A, Part B. ii) Part A is compulsory, which carries 25 marks. In Part A, Answer all questions. iii) In Part B, Answer any one question from each unit. Each question carries 10 marks and may have a, b as sub questions.
Part A
What is a transfer function?
Answer
The transfer function of a linear time-invariant (LTI) system is defined as the ratio of the Laplace transform of the output to the Laplace transform of the input, assuming all initial conditions are zero.
Why negative feedback is invariably preferred in a closed loop system?
Answer
Negative feedback is preferred because it reduces system sensitivity to parameter variations, improves bandwidth, reduces noise and distortion, and stabilizes the gain of the system. While it reduces overall gain, the resulting improvement in system performance and robustness outweighs this disadvantage.
What are the standard test signals used in time domain analysis?
Answer
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Draw time response of second order system and represent time domain specifications on it.
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What are the limitations of Routh Criterion?
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Define stability. What is the necessary and sufficient condition for stability?
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State the Nyquist stability theorem.
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Draw the electrical equivalent circuits of lead, lag and lag-lead compensators.
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What is meant by controllability?
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What are the properties of state transition matrix?
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Part B
The dynamic behavior of the system is described by the equation, 6(dc/dt) + c = r, where ‘c’ is the output and ‘r’ is the input. Determine the transfer function of the system.
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The signal flow graph for a feedback control system is shown in Figure 1. Determine the closed loop transfer function.
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State and explain the Mason’s gain formula.
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Determine the transfer function Eo(s) to Ei(s) for the network shown in Figure 2.
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Damping factor and natural frequency of the system are 0.12 and 84.2 rad/sec respectively. Determine the rise time, peak time, maximum peak overshoot, and settling time.
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A unity feedback control system is characterized by an open loop transfer function G(s)=K/[s(s +5)]. Determine the gain K so that the system will have a damping factor of 0.7. For this value of K determine natural frequency of the system, it is subjected to a unity step input. Obtain the closed loop response of the system in time domain.
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Illustrate the effects of proportional integral control on transient performance of feedback control systems.
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The open loop transfer function of a control system with unity feedback is G(s) = 500 / [s(1 + 0.1s)]. Evaluate the error series for the system and determine the steady state error of the system when an input of r(t) = 1 + 2t + t^2 / 2 ; t > 0 is applied.
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A feedback control system has loop transfer function G(s)H(s) = K / [s(s+2)(s+10)]. Sketch the root locus and determine the range of ‘K’ for which the system is stable.
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Explain the procedure to draw root locus of a given transfer function.
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Open loop Transfer function of unity feedback system given by G(s) = K / [s(s+2)(s+T)]. Using Routh’s Criterion, determine values of K and T which will correspond to a stable system.
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What are steps involved in constructing the Bode plot for a given G(jω)H(jω).
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The open loop transfer function of a unity feedback system is given by G(s) = 5 / [s(2+s)(4+2s)]. Sketch the polar plot and determine the gain margin and phase margin.
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Derive the expressions for frequency domain specifications of a second order system.
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A system is given by G(s)H(s) = 250 / [s(s+1)(s+10)]. (i) Draw Bode plot (ii) Find gain margin & phase margin (iii) Determine the closed loop stability of the system.
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Determine the time response of the system given by state space equations. Where u(t) is the unit step input and x1(0) = x2(0) = 0.
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Test the controllability and observability of the system described.
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For the matrix given, find the Diagonalization matrix A = [[-2, -3], [2, 1]].
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Given the state equation, where A = [[0, 1, 3], [-1, -3, 0], [-2, 0, 0]]. Determine the state transition matrix.
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