JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech II CONTROL SYSTEMS Previous Question Paper (September/October - 2023 - R16)
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
How the control systems are classified?
Answer
Control systems are primarily classified into two categories based on the nature of the control action:
- Open-Loop Control Systems: Systems where the control action is independent of the output; there is no feedback mechanism to correct errors.
- Closed-Loop (Feedback) Control Systems: Systems where the control action is dependent on the output, utilizing a feedback loop to compare the actual output with the desired input to minimize error.
Additionally, they can be classified based on parameters as linear or non-linear, time-invariant or time-variant, and continuous-data or discrete-data systems.
State and explain Mason’s gain formula.
Answer
Mason's Gain Formula is a mathematical technique used to determine the overall transfer function of a complex signal flow graph. It relates the input node to the output node by accounting for all possible forward paths and feedback loops within the system.
The formula is expressed as:
Where:
- Pk is the path gain of the k-th forward path.
- Δ is the graph determinant, calculated as 1 - (sum of all individual loop gains) + (sum of gain products of all possible combinations of two non-touching loops) - (sum of gain products of all combinations of three non-touching loops) + ...
- Δk is the cofactor of the k-th forward path, which is the value of Δ for that part of the graph not touching the k-th forward path.
Define the terms (i) Rise time (ii) Delay time.
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Describe the PID controllers.
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What is frequency response? And, define corner frequency.
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What is break-away and break-in point? How to determine them?
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What is the need of lag-lead compensator?
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What is the difference between polar plot and Nyquist plot?
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What are the demerits of state variable techniques?
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What are the advantages of canonical form?
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Part B
Explain the necessity and effect of feedback in control systems.
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Find the transfer function for a given rotational mechanical system.
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What are the important rules of the block diagram reduction techniques?
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Derive the transfer function of armature-controlled DC servomotor.
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Derive an expression for the time response of a second-order system excited by a unit step Input.
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A closed loop system has two complex conjugate poles at S1, S2 = -2 ± j1. Determine the form of transfer function and values of natural frequency of oscillations, peak time, rise time, settling time and peak overshoot.
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Explain the effect of Proportional control action on the performance of a second order system.
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A unity feedback system with closed loop transfer function is given; show that the steady state error with unit ramp input is determined as required.
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Factorize the given polynomial using Routh– Hurwitz criterion: F(s) = s6 + 2s5 + 8s4 + 12s3 + 20s2 + 16s + 16 = 0.
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Explain the steps for the construction of root locus? From the given root locus plot, how can you determine the gain margin and phase margin?
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List the advantages and limitations of Frequency response methods.
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Draw the bode plot for the unity feedback system. Hence, find gain margin and phase margin.
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Explain the effect of addition of a pole to the transfer function of using polar plot of a given system.
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Explain the design procedure of PID controllers.
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Draw the Nyquist plot for a given transfer function.
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Explain the design procedure for lag compensation in frequency domain.
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Construct the state model for a system characterized by the differential equation y''' + 6y'' + 11y' + 4u = 0. Also, give the block diagram of the model.
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Explain various methods of evaluation of the state transition matrix.
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Write short notes on the following: (i) State transition matrix (ii) Diagonalization
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Obtain the transfer function for linear time invariant system and also draw the state model.
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