# Control theory

1. Oct 21, 2007

### Logarythmic

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

I have a transfer function $G(s) = \frac{1}{s^2}$ and a PI controller $P(s) = 6 \left( 1 + \frac{1}{s} \right)$.

How do I check for stability? Just use 1 + P(s)G(s) = 0 and check the roots?

2. Oct 23, 2007

### CEL

Yes, if all the roots have a negative real part the system is stable.