Chapter 7, Problem 1RQ

To determine

The two sources of Steady state error.

Explanation of Solution

Steady state error: It is defined as the difference between the input and the output of a system. The steady state error can be calculated by using final value theorem, it is represented as e_ss.

Final value theorem is:

e_ss= $\underset{x\to \infty }{\lim }e(t)=\underset{s\to 0}{\lim }sE(S)$

E(s) is Laplace transform of the error signal e(t).

Two sources of steady state errors are:

• Steady state error in control system arises from nonlinear sources, such as backlash in gear or a motor that will not move because the input voltage exceeds a threshold.
• Steady state error arises from the configuration of the system itself and applied input (Step, Ramp, Parabolic).