Study Guide

System Performance Study Guide
(Links to material about system performance)

System performance is what is it all about. It includes topics like system accuracy, speed of response, stability and relative stability.

System performance is important. You design control systems so that you can obtain good system performance. 'nuff said.

Before you can learn about system performance, you need to know how to calculate how systems respond. That includes topics like step response (1st order and 2nd order) and impulse response, for example. Basically, when you talk about system performance, you are talking about details of system response, and you need to know a lot about system dynamics.
You also need a good understanding of how performance measures and system paramters are inter-related. For example, you need a good understanding of how bandwidth and response time are related.

Time response of a system is important, and there are several ways of measuring various aspects of the time response of a system.

The accuracy of a system is usually measured using Steady State Error (SSE).
The speed of response is measured in many different ways. It gets complicated because higher order systems can't be described with a single time-constant. Higher order systems often use arbitrary measures of speed of response like rise time and settling time. You will find that in first order systems rise time and settling time are related to the time constant.

We are usually concerned with closed loop systems, and you need to be able to relate open loop characteristics to closed loop characteristics that determine performance. A lot of that relies on interpreting a root locus.
In many cases, design of a closed loop system is done using frequency response methods, and you need to do things like relate closed loop bandwidth to rise time, etc.

When you design a control system you are manipulating parts of the system in a closed loop in order to make the overall system - the closed loop system - behave in a way that you want - which may be a way specified by a purchaser, etc. You're dealing with measures of system performance, and they will be measured.