Specification Unaffected by K

Correct Answer

D — Settling time

Concept and Reasoning

For the unity-feedback characteristic equation Js²+Bs+K=0, ωn=√(K/J) and ζ=B/(2√(JK)). Their product ζωn=B/(2J) is independent of K. Since the 2% settling time is approximately 4/(ζωn), settling time is unaffected by K.

Calculation / Key Relation

Ts≈4/(ζωn)=8J/B

Exam Takeaway

Look for a specification depending on the product ζωn.

Common Mistake

Do not assume every transient specification changes when the loop gain changes.