Gain Margin

Discussion in 'Homework Help' started by acrofts84, May 14, 2012.

  1. acrofts84

    Thread Starter New Member

    Aug 12, 2010

    I'm trying to find the gain margin for a system with a 1/s^2 term.

    The gain margin is the change in open loop gain required at 180 deg of phase shift to make the closed loop system unstable.

    The 1/s^2 term makes the phase -180 deg regardless so how do I graphically find the gain margin.

    The transfer function is:

    25(s+4) / (s^2 (s + 10)^2)

    Thanks for your help!