Question

Write down a transfer function of a stable system for which pure proportional feedback could drive the system unstable.

Answer 1

Answer:

$Gs = 1 / (s + 1)^3$

Explanation:

A system is known to be a stable system if the poles of the system lie on the negative real axis of the s plane.

A system that could be driven unstable by a P-controller would be:

$Gs = 1 / (s + 1)^3$

As the value of K increases, the closed loop poles move into the right half s plane