Control Systems interview questions

27 Control Systems questions from the ECE Core bank, written for Indian campus drives and tech interviews. Every question has a verified answer and an AI-tutor explanation on placd.

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1. What is Static error constants?

Junior
  1. A.network with pole nearer the origin than its zero placed well below crossover, raising low-frequency gain to cut steady-state error without disturbing transient response
  2. B.Kp, Kv and Ka are the low-frequency limits of G(s), sG(s) and s²G(s); a type-1 system has zero step error and ramp error 1/Kv
  3. C.network with zero nearer the origin than its pole that adds phase near gain crossover, improving phase margin and speed at the cost of wider bandwidth and noise
  4. D.path traced by closed-loop poles as gain varies from zero to infinity, starting at open-loop poles and ending at open-loop zeros or along asymptotes to infinity

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2. Which term means: "Kp, Kv and Ka are the low-frequency limits of G(s), sG(s) and s²G(s); a type-1 system has zero step error and ramp error 1/Kv"?

Junior
  1. A.Lead compensator
  2. B.Ziegler-Nichols closed-loop tuning
  3. C.Static error constants
  4. D.Peak overshoot

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3. Which statement is correct?

Junior
  1. A.Static error constants — network with pole nearer the origin than its zero placed well below crossover, raising low-frequency gain to cut steady-state error without disturbing transient response
  2. B.Static error constants — Kp, Kv and Ka are the low-frequency limits of G(s), sG(s) and s²G(s); a type-1 system has zero step error and ramp error 1/Kv
  3. C.Static error constants — time for the response to enter and stay within a ±2% band of its final value, approximately 4/(ζωn) for a second-order system
  4. D.Static error constants — maximum excursion beyond the final value, e^(−πζ/√(1−ζ²)) for a second-order system, depending only on damping ratio and about 16% at ζ = 0.5

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4. What is Peak overshoot?

Junior
  1. A.maximum excursion beyond the final value, e^(−πζ/√(1−ζ²)) for a second-order system, depending only on damping ratio and about 16% at ζ = 0.5
  2. B.Kp, Kv and Ka are the low-frequency limits of G(s), sG(s) and s²G(s); a type-1 system has zero step error and ramp error 1/Kv
  3. C.state-space property that the initial state can be reconstructed from output measurements, holding when [C; CA; …; CA^(n−1)] has full rank n
  4. D.path traced by closed-loop poles as gain varies from zero to infinity, starting at open-loop poles and ending at open-loop zeros or along asymptotes to infinity

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5. Which term means: "maximum excursion beyond the final value, e^(−πζ/√(1−ζ²)) for a second-order system, depending only on damping ratio and about 16% at ζ = 0.5"?

Junior
  1. A.Peak overshoot
  2. B.Static error constants
  3. C.Lead compensator
  4. D.Root locus

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6. Which statement is correct?

Junior
  1. A.Peak overshoot — path traced by closed-loop poles as gain varies from zero to infinity, starting at open-loop poles and ending at open-loop zeros or along asymptotes to infinity
  2. B.Peak overshoot — network with pole nearer the origin than its zero placed well below crossover, raising low-frequency gain to cut steady-state error without disturbing transient response
  3. C.Peak overshoot — maximum excursion beyond the final value, e^(−πζ/√(1−ζ²)) for a second-order system, depending only on damping ratio and about 16% at ζ = 0.5
  4. D.Peak overshoot — network with zero nearer the origin than its pole that adds phase near gain crossover, improving phase margin and speed at the cost of wider bandwidth and noise

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7. What is Settling time?

Junior
  1. A.Kp, Kv and Ka are the low-frequency limits of G(s), sG(s) and s²G(s); a type-1 system has zero step error and ramp error 1/Kv
  2. B.network with pole nearer the origin than its zero placed well below crossover, raising low-frequency gain to cut steady-state error without disturbing transient response
  3. C.state-space property that the initial state can be reconstructed from output measurements, holding when [C; CA; …; CA^(n−1)] has full rank n
  4. D.time for the response to enter and stay within a ±2% band of its final value, approximately 4/(ζωn) for a second-order system

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8. Which term means: "time for the response to enter and stay within a ±2% band of its final value, approximately 4/(ζωn) for a second-order system"?

Junior
  1. A.Ziegler-Nichols closed-loop tuning
  2. B.Settling time
  3. C.Static error constants
  4. D.Root locus

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9. Which statement is correct?

Junior
  1. A.Settling time — time for the response to enter and stay within a ±2% band of its final value, approximately 4/(ζωn) for a second-order system
  2. B.Settling time — network with zero nearer the origin than its pole that adds phase near gain crossover, improving phase margin and speed at the cost of wider bandwidth and noise
  3. C.Settling time — magnitude in dB and phase against log frequency, where each real pole contributes −20 dB/decade and −90° asymptotically, letting gain and phase margins be read directly
  4. D.Settling time — Kp, Kv and Ka are the low-frequency limits of G(s), sG(s) and s²G(s); a type-1 system has zero step error and ramp error 1/Kv

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10. What is Root locus?

Mid
  1. A.network with pole nearer the origin than its zero placed well below crossover, raising low-frequency gain to cut steady-state error without disturbing transient response
  2. B.maximum excursion beyond the final value, e^(−πζ/√(1−ζ²)) for a second-order system, depending only on damping ratio and about 16% at ζ = 0.5
  3. C.path traced by closed-loop poles as gain varies from zero to infinity, starting at open-loop poles and ending at open-loop zeros or along asymptotes to infinity
  4. D.PID rules from ultimate gain Ku and period Pu: Kp = 0.6Ku, Ti = 0.5Pu, Td = 0.125Pu, giving roughly quarter-amplitude decay

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11. Which term means: "path traced by closed-loop poles as gain varies from zero to infinity, starting at open-loop poles and ending at open-loop zeros or along asymptotes to infinity"?

Mid
  1. A.Peak overshoot
  2. B.Lead compensator
  3. C.Ziegler-Nichols closed-loop tuning
  4. D.Root locus

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12. Which statement is correct?

Mid
  1. A.Root locus — path traced by closed-loop poles as gain varies from zero to infinity, starting at open-loop poles and ending at open-loop zeros or along asymptotes to infinity
  2. B.Root locus — state-space property that the initial state can be reconstructed from output measurements, holding when [C; CA; …; CA^(n−1)] has full rank n
  3. C.Root locus — time for the response to enter and stay within a ±2% band of its final value, approximately 4/(ζωn) for a second-order system
  4. D.Root locus — PID rules from ultimate gain Ku and period Pu: Kp = 0.6Ku, Ti = 0.5Pu, Td = 0.125Pu, giving roughly quarter-amplitude decay

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13. What is Bode plot?

Mid
  1. A.magnitude in dB and phase against log frequency, where each real pole contributes −20 dB/decade and −90° asymptotically, letting gain and phase margins be read directly
  2. B.maximum excursion beyond the final value, e^(−πζ/√(1−ζ²)) for a second-order system, depending only on damping ratio and about 16% at ζ = 0.5
  3. C.path traced by closed-loop poles as gain varies from zero to infinity, starting at open-loop poles and ending at open-loop zeros or along asymptotes to infinity
  4. D.network with pole nearer the origin than its zero placed well below crossover, raising low-frequency gain to cut steady-state error without disturbing transient response

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14. Which term means: "magnitude in dB and phase against log frequency, where each real pole contributes −20 dB/decade and −90° asymptotically, letting gain and phase margins be read directly"?

Mid
  1. A.Bode plot
  2. B.Lag compensator
  3. C.Ziegler-Nichols closed-loop tuning
  4. D.Root locus

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15. Which statement is correct?

Mid
  1. A.Bode plot — time for the response to enter and stay within a ±2% band of its final value, approximately 4/(ζωn) for a second-order system
  2. B.Bode plot — state-space property that the initial state can be reconstructed from output measurements, holding when [C; CA; …; CA^(n−1)] has full rank n
  3. C.Bode plot — maximum excursion beyond the final value, e^(−πζ/√(1−ζ²)) for a second-order system, depending only on damping ratio and about 16% at ζ = 0.5
  4. D.Bode plot — magnitude in dB and phase against log frequency, where each real pole contributes −20 dB/decade and −90° asymptotically, letting gain and phase margins be read directly

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16. What is Lead compensator?

Mid
  1. A.maximum excursion beyond the final value, e^(−πζ/√(1−ζ²)) for a second-order system, depending only on damping ratio and about 16% at ζ = 0.5
  2. B.Kp, Kv and Ka are the low-frequency limits of G(s), sG(s) and s²G(s); a type-1 system has zero step error and ramp error 1/Kv
  3. C.network with zero nearer the origin than its pole that adds phase near gain crossover, improving phase margin and speed at the cost of wider bandwidth and noise
  4. D.magnitude in dB and phase against log frequency, where each real pole contributes −20 dB/decade and −90° asymptotically, letting gain and phase margins be read directly

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17. Which term means: "network with zero nearer the origin than its pole that adds phase near gain crossover, improving phase margin and speed at the cost of wider bandwidth and noise"?

Mid
  1. A.Lead compensator
  2. B.Observability
  3. C.Peak overshoot
  4. D.Static error constants

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18. Which statement is correct?

Mid
  1. A.Lead compensator — path traced by closed-loop poles as gain varies from zero to infinity, starting at open-loop poles and ending at open-loop zeros or along asymptotes to infinity
  2. B.Lead compensator — time for the response to enter and stay within a ±2% band of its final value, approximately 4/(ζωn) for a second-order system
  3. C.Lead compensator — network with zero nearer the origin than its pole that adds phase near gain crossover, improving phase margin and speed at the cost of wider bandwidth and noise
  4. D.Lead compensator — state-space property that the initial state can be reconstructed from output measurements, holding when [C; CA; …; CA^(n−1)] has full rank n

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19. What is Lag compensator?

Mid
  1. A.path traced by closed-loop poles as gain varies from zero to infinity, starting at open-loop poles and ending at open-loop zeros or along asymptotes to infinity
  2. B.network with pole nearer the origin than its zero placed well below crossover, raising low-frequency gain to cut steady-state error without disturbing transient response
  3. C.magnitude in dB and phase against log frequency, where each real pole contributes −20 dB/decade and −90° asymptotically, letting gain and phase margins be read directly
  4. D.state-space property that the initial state can be reconstructed from output measurements, holding when [C; CA; …; CA^(n−1)] has full rank n

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20. Which term means: "network with pole nearer the origin than its zero placed well below crossover, raising low-frequency gain to cut steady-state error without disturbing transient response"?

Mid
  1. A.Ziegler-Nichols closed-loop tuning
  2. B.Lead compensator
  3. C.Lag compensator
  4. D.Static error constants

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21. Which statement is correct?

Mid
  1. A.Lag compensator — time for the response to enter and stay within a ±2% band of its final value, approximately 4/(ζωn) for a second-order system
  2. B.Lag compensator — network with pole nearer the origin than its zero placed well below crossover, raising low-frequency gain to cut steady-state error without disturbing transient response
  3. C.Lag compensator — magnitude in dB and phase against log frequency, where each real pole contributes −20 dB/decade and −90° asymptotically, letting gain and phase margins be read directly
  4. D.Lag compensator — maximum excursion beyond the final value, e^(−πζ/√(1−ζ²)) for a second-order system, depending only on damping ratio and about 16% at ζ = 0.5

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22. What is Observability?

Senior
  1. A.network with zero nearer the origin than its pole that adds phase near gain crossover, improving phase margin and speed at the cost of wider bandwidth and noise
  2. B.state-space property that the initial state can be reconstructed from output measurements, holding when [C; CA; …; CA^(n−1)] has full rank n
  3. C.magnitude in dB and phase against log frequency, where each real pole contributes −20 dB/decade and −90° asymptotically, letting gain and phase margins be read directly
  4. D.PID rules from ultimate gain Ku and period Pu: Kp = 0.6Ku, Ti = 0.5Pu, Td = 0.125Pu, giving roughly quarter-amplitude decay

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23. Which term means: "state-space property that the initial state can be reconstructed from output measurements, holding when [C; CA; …; CA^(n−1)] has full rank n"?

Senior
  1. A.Ziegler-Nichols closed-loop tuning
  2. B.Settling time
  3. C.Observability
  4. D.Static error constants

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24. Which statement is correct?

Senior
  1. A.Observability — state-space property that the initial state can be reconstructed from output measurements, holding when [C; CA; …; CA^(n−1)] has full rank n
  2. B.Observability — PID rules from ultimate gain Ku and period Pu: Kp = 0.6Ku, Ti = 0.5Pu, Td = 0.125Pu, giving roughly quarter-amplitude decay
  3. C.Observability — Kp, Kv and Ka are the low-frequency limits of G(s), sG(s) and s²G(s); a type-1 system has zero step error and ramp error 1/Kv
  4. D.Observability — network with pole nearer the origin than its zero placed well below crossover, raising low-frequency gain to cut steady-state error without disturbing transient response

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25. What is Ziegler-Nichols closed-loop tuning?

Senior
  1. A.PID rules from ultimate gain Ku and period Pu: Kp = 0.6Ku, Ti = 0.5Pu, Td = 0.125Pu, giving roughly quarter-amplitude decay
  2. B.time for the response to enter and stay within a ±2% band of its final value, approximately 4/(ζωn) for a second-order system
  3. C.state-space property that the initial state can be reconstructed from output measurements, holding when [C; CA; …; CA^(n−1)] has full rank n
  4. D.path traced by closed-loop poles as gain varies from zero to infinity, starting at open-loop poles and ending at open-loop zeros or along asymptotes to infinity

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26. Which term means: "PID rules from ultimate gain Ku and period Pu: Kp = 0.6Ku, Ti = 0.5Pu, Td = 0.125Pu, giving roughly quarter-amplitude decay"?

Senior
  1. A.Lead compensator
  2. B.Root locus
  3. C.Observability
  4. D.Ziegler-Nichols closed-loop tuning

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27. Which statement is correct?

Senior
  1. A.Ziegler-Nichols closed-loop tuning — state-space property that the initial state can be reconstructed from output measurements, holding when [C; CA; …; CA^(n−1)] has full rank n
  2. B.Ziegler-Nichols closed-loop tuning — Kp, Kv and Ka are the low-frequency limits of G(s), sG(s) and s²G(s); a type-1 system has zero step error and ramp error 1/Kv
  3. C.Ziegler-Nichols closed-loop tuning — magnitude in dB and phase against log frequency, where each real pole contributes −20 dB/decade and −90° asymptotically, letting gain and phase margins be read directly
  4. D.Ziegler-Nichols closed-loop tuning — PID rules from ultimate gain Ku and period Pu: Kp = 0.6Ku, Ti = 0.5Pu, Td = 0.125Pu, giving roughly quarter-amplitude decay

Answer + AI explanation with Pro

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