The steady-state value of the step response is called the DC gain of the system:
where .
By the Final Value Theorem, we can compute DC gain with easy (when FVT holds). For example, for the unit step response where we have
If all poles of are strictly stable, then by FVT
Example
Given the system transfer function
compute the DC gain of the system.
All the poles of are strictly stable poles (Routh-Hurwitz Criterion), so