Microcontroller Based Applied Digital Control

Preface xi

1 Introduction 1

1.1 The Idea of System Control 1

1.2 Computer in the Loop 2

1.3 Centralized and Distributed Control Systems 5

1.4 Scada Systems 6

1.5 Hardware Requirements for Computer Control 7

1.6 Software Requirements for Computer Control 9

1.7 Sensors Used in Computer Control 14

1.8 Exercises 24

2 System Modelling 27

2.1 Mechanical Systems 27

2.2 Electrical Systems 37

2.3 Electromechanical Systems 42

2.4 Fluid Systems 44

2.5 Thermal Systems 49

2.6 Exercises 52

3 The PIC Microcontroller 57

3.1 The PIC Microcontroller Family 57

3.2 Minimum PIC Configuration 61

3.3 Some Popular PIC Microcontrollers 66

3.4 Exercises 75

4 Programming PIC Microcontrollers in C 77

4.1 PICC Lite Variable Types 78

4.2 Variables 80

4.3 Comments in Programs 81

4.4 Storing Variables in the Program Memory 82

4.5 Static Variables 82

4.6 Volatile Variables 83

4.7 Persistent Variables 83

4.8 Absolute Address Variables 83

4.9 Bank1 Qualifier 83

4.10 Arrays 84

4.11 ASCII Constants 86

4.12 Arithmetic and Logic Operators 86

4.13 Number Bases 89

4.14 Structures 89

4.15 Program Flow Control 91

4.16 Functions in C 96

4.17 Pointers in C 99

4.18 Pre-processor Commands 101

4.19 Accessing the EEPROM Memory 104

4.20 Interupts in C Programs 104

4.21 Delays in C Programs 105

4.22 Structure of a C Program 105

4.23 PIC Microcontroller Input-Output Interface 107

4.24 Exercises 116

5 Microcontroller Project Development 119

5.1 Hardware and Software Requirements 119

5.2 Program Development Tools 120

5.3 Exercise 129

6 Sampled Data Systems and the z-Transform 131

6.1 The Sampling Process 131

6.2 The z-Transform 136

6.3 Pulse Transfer Function and Manipulation of Block Diagrams 154

6.4 Exercises 166

7 System Time Response Characteristics 171

7.1 Time Response Comparison 171

7.2 Time Domain Specifications 174

7.3 Mapping the s-Plane into the z-Plane 177

7.4 Damping Ratio and Undamped Natural Frequency in the z-Plane 178

7.5 Damping Ratio and Undamped Natural Frequency Using Formulae 181

7.6 Exercises 183

8 System Stability 187

8.1 Factorizing the Characteristic Equation 187

8.2 Jury's Stability Test 189

8.3 Routh-Hurwitz Criterion 192

8.4 Root Locus 194

8.5 Nyquist Criterion 201

8.6 Bode Diagrams 205

8.7 Exercises 208

9 Discrete Controller Design 213

9.1 Digital Controllers 214

9.2 PID Controller 230

9.3 Exercises 137

10 Controller Realization 243

10.1 Direct Structure 243

10.2 Cascade Realization 246

10.3 Parallel Realization 249

10.4 PID Controller Implementations 250

10.5 Microcontroller Implementations 253

10.6 Choice of Sampling Interval 263

10.7 Exercises 267

Further Reading 268

11 Liquid Level Digital Control System: a Case Study 269

11.1 The System Schematic 269

11.2 System Model 270

11.3 Identification of the System 273

11.4 Designing a Controller 274

11.5 Conclusions 278

Appendix A Table of z-Transforms 283

Appendix B MATLAB Tutorial 285

Index 307