JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech II CONTROL SYSTEMS Previous Question Paper (December - 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.
Part A
What are the advantages and disadvantages of positive feed back control systems.
Answer
Advantages: Positive feedback increases the overall gain of the system and improves sensitivity to parameter variations. Disadvantages: It decreases the stability of the system and increases the noise and distortion levels.
Explain the translatory and rotary elements of mechanical system.
Answer
Translatory mechanical elements include mass (stores kinetic energy), spring (stores potential energy), and dashpot (dissipates energy via friction). Rotary mechanical elements include moment of inertia (stores kinetic energy), torsional spring (stores potential energy), and rotational damper (dissipates energy).
What are the advantages of signal flow graph over block diagram reduction technique?
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Write the differences between AC servo motor and DC servo motor.
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What is difference between type and order of the system?
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Write the advantages of PD controller and PI controller of second order system.
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Define the concept of Routh Hurwitz criteria.
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What is PID controller?
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What are the advantages and limitations of frequency response analysis?
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Write the advantages of bode plot.
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Part B
Explain the advantages and features of transfer function.
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Obtain the transfer function X1(s)/F(s) for the mechanical system as shown in figure 1.
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Explain Open Loop and closed loop control systems with examples and classify control systems.
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Derive the transfer function for the following rotational mechanical systems shown in the figure 2.
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Briefly describe Synchro transmitter and Receiver pair.
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Determine the transfer function C(S)/R(S) for the block diagram shown in Figure 3.
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Derive Transfer Function of DC Servo motor.
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Obtain transfer function C(s)/R(s) using signal flow graph shown in figure 4.
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Derive expressions for rise time, peak over shoot, settling time of 2nd order system of unit step input.
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The open loop transfer function of a control system with unity feedback is given by G(s) = 100 / [s(s+10)]. Determine the steady state error of the system when the input is 10+10t+4t2.
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A unit feedback 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 ratio of 0.5. For this value of K, determine settling time, peak overshoot and times to peak overshoot for a unit-step input.
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The open loop transfer function of unity feedback system is given by G(s) = K / [s(1+Ts)]. By what factor the amplifier gain be reduced so that (i) The peak overshoot of unit step response of the system is reduced from 80% to 20% (ii) The damping ratio increases from 0.2 to 0.7.
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Determine the range of K for stability of a unity-feedback control system whose open loop transfer function is given.
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Sketch the root locus plot of the system whose open loop transfer function is given.
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Explain different conditions for stability using RH criteria.
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Sketch the root locus diagram for a unity feedback system. Thus find the value of K at a point where the complex poles provide a damping factor of 0.5.
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The open loop transfer function of a unity feedback system is: G(s) = K / [(1+0.02s)(1+0.04s)]. Draw the Bode plot and find the gain margin and phase margin. Also find the value of open loop gain so that the system has a phase margin of 45o.
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For a system having G(s)=k/s(s+2)(s+20), H(s)=1, construct bode plot and determine:
limiting value of K for the system to be stable
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value of k for the gain margin to be 10db
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value of k for the phase margin to be 50o
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