Control Systems Flashcards
7 cards from real BME practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Control Systems flashcards as text
The Routh-Hurwitz criterion determines system stability by:
Answer: Examining the signs of elements in the Routh array without computing roots
The Routh-Hurwitz criterion constructs a Routh array from the characteristic equation coefficients and assesses stability by checking for sign changes in the first column, avoiding direct root computation.
A second-order system with damping ratio ζ = 0.5 is classified as:
Answer: Underdamped
An underdamped system has 0 < ζ < 1; with ζ = 0.5 the system exhibits oscillatory step response with overshoot that decays to the final value.
The gain margin of a control system is measured at the frequency where the open-loop phase angle equals:
Answer: −180°
Gain margin is evaluated at the phase crossover frequency ωpc where ∠G(jω)H(jω) = −180°, and it equals the reciprocal of the open-loop magnitude at that frequency.
In a Bode magnitude plot, a first-order lag factor (1 + jωT)^(−1) has a high-frequency asymptotic slope of:
Answer: −20 dB/decade
A single real pole contributes a −20 dB/decade asymptote above its corner frequency (ω = 1/T), reflecting the −1 power in the denominator factor.
Root locus plots the trajectories of closed-loop poles as:
Answer: Open-loop gain K varies from 0 to ∞
Root locus shows how the closed-loop poles migrate in the s-plane as the open-loop gain K increases from 0 to infinity, starting at open-loop poles and ending at open-loop zeros.
The phase margin of a stable feedback system is the additional phase lag that would cause:
Answer: The system to become marginally stable (oscillatory)
Phase margin is measured at the gain crossover frequency (|G(jω)| = 1) and represents the additional phase lag required to bring the system to the verge of instability (−180° total phase).
Which of the following transfer functions represents a pure integrator?
Answer: K/s
A pure integrator has transfer function K/s, corresponding to the time-domain operation of integration, and introduces a pole at the origin of the s-plane.