# Feedback Control Systems

1. Mar 3, 2010

### l46kok

1. The problem statement, all variables and given/known data

http://img24.imageshack.us/img24/9028/72841137.jpg [Broken]

2. Relevant equations

Routh-Hurwitz Stability Criterion

3. The attempt at a solution

For first question, you just write the Routh Array, make sure that the first row is all positive and you get Kmax = 1. Simple enough

How would I approach the second question though? Any starters would be sincerely appreciated.

Last edited by a moderator: May 4, 2017
2. Mar 4, 2010

### CEL

You got the value K = 1 by making the line $$s^1$$ equal to zero. Now, you form an auxiliary equation with the coefficients of the $$s^2$$ line. The roots of the auxiliary equation are also roots of the characteristic equation. Solve it and you get two imaginary roots, whose module is the oscillation frequency when K = 1.

Last edited by a moderator: May 4, 2017