Fig.2.14 Block diagram of a stabilizing system

Using Eq.(2.1) and (2.2) we may have:

(2.3)

The higher is the value of the disturbance input signal the lower is the value of the controlled variable.

If Z = 0 (the case when disturbance in put signal is absent) we may obtain:

In this case the steady-state (static) error will be:

(2.4)