文档介绍：INSTRUMENTATION AND CONTROL
TUTORIAL 3 – TRANSFER FUNCTION MANIPULATION
This tutorial is of interest to any student studying control systems and in particular the EC
module D227 – Control System Engineering.
pletion of this tutorial, you should be able to do the following.
• Explain a basic open loop system.
• Explain a basic closed loop system.
• Explain the use of negative feedback
• Manipulate transfer functions.
• Explain the use of velocity feedback.
• Explain the affect of disturbances to the output of a system.
• Explain the use of proportional and derivative feedback.
• plex systems to a single transfer function.
If you are not familiar with instrumentation used in control engineering, you should
complete the tutorials on Instrumentation Systems.
In order plete the theoretical part of this tutorial, you must be familiar with basic
mechanical and electrical science.
You must also be familiar with the use of transfer functions and the Laplace Transform
(see maths tutorials).
1
1. INTRODUCTION
The function of any control system is to automatically regulate the output and keep it at the desired value.
The desired value is the input to the system. If the input is changed the output must respond and change to
the new set value. If something happens to disturb the output without a change to the input, the output
must return to the correct value. Here is a short list of some of the things we might be controlling.
The speed or angle of a motor (electric or hydraulic)
The speed or position of a linear actuator (. in robotics, ship’s stabilisers, aircraft control etcetera)
The temperature of an oven (. heat treatment)
The pressure of a vessel (. a steam boiler)
The quantity inside a container (. metering contents in a vessel)
The flow of solids, liquids and gases (. controlling the steam flow to a turbine)
The