PPT - Introduction Digital Control Systems - Electrical Engineering (EE) PDF Download

 Page 1


DigitalControl
Systems
INTRODUCTION
Page 2


DigitalControl
Systems
INTRODUCTION
Introduction
What is a control system?
Objective:
To make the system OUTPUT and the desired REFERENCE as close as possible, i.e., to make the ERROR as
small as possible.
Key Issues:
1) How to describe the system to be controlled? (Modeling)
2) How to design the controller? (Control)
Page 3


DigitalControl
Systems
INTRODUCTION
Introduction
What is a control system?
Objective:
To make the system OUTPUT and the desired REFERENCE as close as possible, i.e., to make the ERROR as
small as possible.
Key Issues:
1) How to describe the system to be controlled? (Modeling)
2) How to design the controller? (Control)
Introduction
What is important in a control system?
Stability
 (Transient) response speed
 Accuracy
Ødynamic overshooting and oscillation duration
ØSteady state error
 Robustness
Øerrors in models (uncertainties and nonlinearities)
Øeffects of disturbances
Øeffects of noises
Page 4


DigitalControl
Systems
INTRODUCTION
Introduction
What is a control system?
Objective:
To make the system OUTPUT and the desired REFERENCE as close as possible, i.e., to make the ERROR as
small as possible.
Key Issues:
1) How to describe the system to be controlled? (Modeling)
2) How to design the controller? (Control)
Introduction
What is important in a control system?
Stability
 (Transient) response speed
 Accuracy
Ødynamic overshooting and oscillation duration
ØSteady state error
 Robustness
Øerrors in models (uncertainties and nonlinearities)
Øeffects of disturbances
Øeffects of noises
Introduction
Modeling of dynamic systems
Model: A representation of a system.
Types of Models:
 Physical models (prototypes)
 Mathematical models (e.g., input-output relationships)
Analytical models (using physical laws)
Computer (numerical) models
Experimental models (using input/output experimental data)
Models for physical dynamic systems:
Lumped-parameter models
Continuous-parameter models. Example: Spring element (flexibility, inertia,
damping)
Page 5


DigitalControl
Systems
INTRODUCTION
Introduction
What is a control system?
Objective:
To make the system OUTPUT and the desired REFERENCE as close as possible, i.e., to make the ERROR as
small as possible.
Key Issues:
1) How to describe the system to be controlled? (Modeling)
2) How to design the controller? (Control)
Introduction
What is important in a control system?
Stability
 (Transient) response speed
 Accuracy
Ødynamic overshooting and oscillation duration
ØSteady state error
 Robustness
Øerrors in models (uncertainties and nonlinearities)
Øeffects of disturbances
Øeffects of noises
Introduction
Modeling of dynamic systems
Model: A representation of a system.
Types of Models:
 Physical models (prototypes)
 Mathematical models (e.g., input-output relationships)
Analytical models (using physical laws)
Computer (numerical) models
Experimental models (using input/output experimental data)
Models for physical dynamic systems:
Lumped-parameter models
Continuous-parameter models. Example: Spring element (flexibility, inertia,
damping)
Introduction
Signal categories for identifying control system types
Continuous-time signal & quantized signal
Continuous-time signal is defined continuously in the time domain. Figure on the left
shows a continuous-time signal, represented by x(t).
Quantized signal is a signal whose amplitudes are discrete and limited. Figure on the right
shows a quantized signal.
Analog signal or continuous signal is continuous in time and in amplitude. The real word
consists of analog signals.