BME Control Systems 2

Question 1

The Routh-Hurwitz criterion determines system stability by:

Accepted Answer

Examining the signs of elements in the Routh array without computing roots

Answer

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.

Question 2

A second-order system with damping ratio ζ = 0.5 is classified as:

Accepted Answer

Underdamped

Answer

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.

Question 3

The gain margin of a control system is measured at the frequency where the open-loop phase angle equals:

Accepted Answer

−180°

Answer

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.

Question 4

In a Bode magnitude plot, a first-order lag factor (1 + jωT)^(−1) has a high-frequency asymptotic slope of:

Accepted Answer

−20 dB/decade

Answer

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.

Question 5

Root locus plots the trajectories of closed-loop poles as:

Accepted Answer

Open-loop gain K varies from 0 to ∞

Answer

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.

BME - Bachelor of Mechanical Engineering Practice Test

BME - Bachelor of Mechanical Engineering Practice Test

BME Control Systems 2