JNTU
JNTU B.Tech III Year CONTROL SYSTEMS ENGINEERING Previous Question Paper (March - 2021 - R15)
Answer any five questions. All questions carry equal marks.
Main
Write the differences between open loop and closed loop control systems.
Answer
| Feature | Open Loop Control System | Closed Loop Control System |
|---|---|---|
| Feedback | No feedback present | Feedback is present |
| Complexity | Simple and economical | Complex and expensive |
| Accuracy | Less accurate | Highly accurate |
| Stability | Generally stable | May become unstable |
| Sensitivity | Sensitive to parameter variations | Less sensitive to parameter variations |
| Calibration | Requires frequent calibration | Calibration is less critical |
Find the transfer function
Answer
For an electrical circuit consisting of a resistor R and capacitor C in series, the input voltage V(s) is related to the current I(s) and the output voltage Vc(s) across the capacitor.
Applying Kirchhoff's Voltage Law (KVL) in the s-domain:
The voltage across the capacitor is given by:
From this, the current I(s) is:
Substituting I(s) into the KVL equation:
The transfer function is the ratio of output to input:
Obtain the transfer function for the following signal flow graph using mason’s gain formula (figure 2).
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Determine the expression for output response when a standard second order system is excited with a unit step input. Also sketch the responses for various dampings.
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State and explain different error constants in steady state error analysis.
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A unity feedback control system has open loop transfer function
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Sketch the Root-locus for the open loop transfer function
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Explain the Routh-Hurwitz criteria to predict system stability. State its limitations.
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Draw the Bode plot for the system whose open loop transfer function is
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Obtain the solution for the following state space system:
ẋ2 = x3
ẋ3 = -2x1 - 4x2 - 6x3 + u
Here, the initial value is given and 'u' is input variable.
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