Jawaharlal Nehru Technological University Hyderabad
Jawaharlal Nehru Technological University Hyderabad B.Tech III CONTROL SYSTEMS Previous Question Paper (March - 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
Define closed loop control system. Give examples of closed loop control system.
Answer
A closed loop control system is a system in which the control action is dependent on the output of the system. It uses a feedback mechanism to compare the actual output with the desired input to minimize the error. Examples include an automatic electric iron, air conditioning systems, and speed control of a DC motor.
Obtain the transfer function Vc(s)/Vi(s) of the following network (figure 1):
Answer
For an RC series circuit with input voltage Vi(s) and output voltage Vc(s) across the capacitor, the transfer function is derived using the voltage divider rule:
Write the importance of signal flow graph in control systems.
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Compare the AC and DC servomotors.
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Distinguish between type and order of a system.
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What are the standard test signals?
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What is Routh stability criterion?
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Define centroid, how it is calculated in root locus technique?
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Explain Gain cross-over frequency and phase cross-over frequency.
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What is Bode plot? What are the advantages of Bode Plot?
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PART - B
What is feedback? Explain the effects of feedback on control system.
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Explain the mathematical modelling of translatory and rotary elements of mechanical systems.
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Write the differential equations governing the mechanical system shown in figure 2 and determine the transfer function.
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Explain the properties of signal flow graphs.
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Derive the transfer function of an a.c. servomotor and draw its characteristics.
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Determine the transfer function for the following block diagram (figure 3).
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Determine the error coefficients and static error for G(s)=1/(s(s+1)(s+10)), H(s) = s + 2.
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Explain effects of proportional derivative and proportional integral controllers in system performance.
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A unity feedback control system has an open loop transfer function G(S)=5/S(S+5). Find the rise time, settling time and peak over shoot for a step input of 3 units.
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Derive the expressions for peak time and rise time in terms of ξ and ωn for a second order system.
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With the help of Routh Hurwitz criterion comments upon the stability of the system having the characteristic equation: S^6 + 2S^5 + 3S^4 + 7S^3 + 4S^2 + 4S = 0.
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Explain the effects of adding poles and zeros to G(s)H(s) on the root loci by considering one the example.
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Draw the root locus for the unity feedback system whose open loop transfer function is G(s)=k(s+1)/(s(s-1)(s+2)(s+4)).
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Sketch the Bode plots for the system G(s)=25/(s(1+s)(1+0.1s)). Hence find gain cross over frequency and phase cross over frequency.
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Enlist the steps for the construction of Bode plots.
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What are the frequency domain specifications?
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