Introduction

Control
:

is
that quantity responsible for activating the system for produce the output

The word control
is usually taken to mean
regulate, direct, or command.

System
:

is a
combination of elements intended to act together to accomplish an objective.

A
control system :

is a
collection of components working together under the direction of some machine
intelligence.

In
most cases,

electronic
circuits provide the intelligence, and

electromechanical
components such as sensors and motors provide the interface to the physical
world.

Examples
of control systems

Problems
of control engineering

Analysis
and design of control system configurations

Analysis

is
the investigation of the properties of an existing System.

Design

is
the choice and arrangement of control system components to perform a special
task.

Objectives
of analysis are:

The
determination of the following system characteristic:

•The
degree or extent of system stability

•The
steady state performance

•The
transient performance

General procedure for analyzing a linear control system

•
Determine the equations or transfer function for each system component.

•
Choose a scheme for representing the system ( block diagram or signal flow
graph ).

•
Formulate the system model by appropriately connecting the components (blocks, or nodes and branches).

•
Determine the system response characteristics.

By:

1.Time
domain-methods:

direct
solution of the system equations to find the steady state and transient
solutions.
Cumbersome for higher than second order systems.

2.
Graphical
methods.

simpler
and more direct.

__Bode-Plot Representations__

Nyquist
diagrams

Nichols Charts

__The Root-Locus Method__

Design

is
the choice and arrangement of control system components to perform a special
task.

objective
of Design :

__meeting performance specifications.__

performance
specifications

__are the constraints put on system response characteristics.__

Forms
of specifications:

•
Frequency domain specifications
( pertinent
quantities expressed as functions of frequency.)

• Time
domain specifications
(in terms of time response).

These
forms specify the following three important properties of dynamics systems:

•
Speed of response

•
Relative
stability

•
System accuracy or allowable error

Types
of design:

Design
by analysis of system

is
accomplished by modifying the characteristics of an existing or standard system
configuration.

Design
by synthesis (
direct design )

is
accomplished by defining the form of the system directly from its
specifications

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