Project ForgeInstrumentation & Process Control
Controller Modes
GATE 2017
Hard
GOL=Kc·e^(−2s)/s. Based on the Bode criterion for closed-loop stability, the ultimate gain, rounded to 2 decimal places, is
0.79(± 0.03 accepted)
Explanation
Phase=−2ω−π/2=−π at the ultimate frequency ⟹ ωu=π/4=0.785 rad/time. |GOL(ωu)|=Kcu/ωu=1 ⟹ Kcu=ωu=0.785.
Source: GATE CH 2017 (2017)
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