Jawaharlal Nehru Technological University Hyderabad
Jawaharlal Nehru Technological University Hyderabad B.Tech III Year CONTROL SYSTEMS ENGINEERING Previous Question Paper (May - 2018 - R13)
Note: This question paper contains two parts A and B. Part A is compulsory which carries 25 marks. Answer all questions in Part A. Part B consists of 5 Units. Answer any one full question from each unit. Each question carries 10 marks.
Part A
What are the feed-back characteristics?
Answer
Feedback characteristics include increased accuracy, reduced sensitivity to parameter variations, improved disturbance rejection, and the ability to modify system bandwidth and transient response characteristics.
State and write the Mason’s gain formula.
Answer
Mason's gain formula relates the input and output of a signal flow graph. It is given by:
Where Pk is the gain of the k-th forward path, Δ is the determinant of the graph, and Δk is the cofactor of the k-th forward path.
What are the time domain specifications?
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What are the demerits of static error coefficient method?
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What is the concept of stability?
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States the Routh’s stability criterion?
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States the Nyquist stability criterion.
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What is meant by Compensation in control systems?
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States the properties of STM.
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What are the merits of state variable technique?
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Part B
What do you mean by a block diagram? What is meant by summing point and takeoff point? List the merits of block diagram representation.
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Determine the transfer function of the system given in Figure 1.
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Compare the open loop and closed loop control systems.
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Using block diagram reduction technique find the transfer function for the system shown in Figure 2.
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Derive the expression for response of second order system with unit step input.
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For a negative feedback control system G(s) = 8/(s(0.2s+1)) and H(s) = 3/(s+2). Using generalized error series determine the steady state error of the system when the input applied is r(t) = 1+2t+5t^2.
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What is meant by step input, ramp input and impulse input? How do you represent them graphically?
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A unity feedback control system has an open loop transfer function G(s) = 7/(s(s+2)). Determine the time domain specifications for a step input of 10 units.
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Describe the effects of adding poles and zeros to G(s)H(s) on the root loci with necessary diagrams.
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Determine the stability of a closed loop control system whose characteristic equation is s^5+s^4+6s^3+6s^2+9s+9=0.
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For a unity feedback system, the open loop transfer function is G(s) = k / (s(s+1)(s+4)(s+13)). Sketch the root locus and find the value of k to maintain the stability.
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Sketch the bode plot and determine the following: a) Gain cross over frequency, b) Phase cross over frequency, c) Gain margin, d) Phase margin. For the transfer function G(s) = 8 / ((s+3)(s+5)).
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A unit feedback system has an open loop transfer function G(s) = k / (s(s+4)(s+2)). Design a phase lag compensator to meet the specifications, velocity error constant = 7 and phase margin >= 35 degrees.
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Write the general procedure to determine the state space models of a control system.
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Check the controllability and observability of the given system matrices.
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The state variable formulation of a system is given by [x_dot] = [[-1, 0], [-2, -1]][x] + [1, 0]^T u and y = [1, 0][x]. Determine the following: a) Transfer function, b) State transition matrix, c) State equation for a unit step input under zero initial condition.
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