# Control Systems/System Specifications

## System Specification

There are a number of different specifications that might need to be met
by a new system design. In this chapter we will talk about some of the
specifications that systems use, and some of the ways that engineers
analyze and quantify technical systems.

## Steady-State Accuracy

## Sensitivity

The **sensitivity** of a system is a parameter that is specified in
terms of a given output and a given input. The sensitivity measures how
much change is caused in the output by small changes to the reference
input. Sensitive systems have very large changes in output in response
to small changes in the input. The sensitivity of system H to input X is
denoted as:

$$S_H^X(s)$$

## Disturbance Rejection

All physically-realized systems have to deal with a certain amount of
noise and disturbance. The ability of a system to reject the noise is
known as the **disturbance rejection** of the system.

## Control Effort

The control effort is the amount of energy or power necessary for the
controller to perform its duty.

