27 real Control Systems questions from the ECE Core bank, as asked in Indian campus drives and tech interviews. Every question has a verified answer and an AI-tutor explanation on placd — free to start.
1. What is Static error constants?
Junior
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
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
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
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
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
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
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
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
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
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
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
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
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"?
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
D.PID rules from ultimate gain Ku and period Pu: Kp = 0.6Ku, Ti = 0.5Pu, Td = 0.125Pu, giving roughly quarter-amplitude decay
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"?
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
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
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
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
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
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
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
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
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"?
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
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
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
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
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
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
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
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
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"?
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
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
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
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
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
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
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
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
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"?
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
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
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
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
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
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
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
D.PID rules from ultimate gain Ku and period Pu: Kp = 0.6Ku, Ti = 0.5Pu, Td = 0.125Pu, giving roughly quarter-amplitude decay
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"?
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
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
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
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
A.PID rules from ultimate gain Ku and period Pu: Kp = 0.6Ku, Ti = 0.5Pu, Td = 0.125Pu, giving roughly quarter-amplitude decay
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
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
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
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
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
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
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
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