Control System Design Guide

Using Your Computer to Understand and Diagnose Feedback Controllers

George Ellis

• Publisher: Butterworth-Heinemann
• Year: 2012
• ISBN:
  9780123859211
• Edition: 4
• Topic: Tecnologia e ingegneria
• Subtopic: Ingegneria meccanica

Control Systems Design Guide has helped thousands of engineers to improve machine performance. This fourth edition of the practical guide has been updated with cutting-edge control design scenarios, models and simulations enabling apps from battlebots to solar collectors. This useful reference enhances coverage of practical applications via the inclusion of new control system models, troubleshooting tips, and expanded coverage of complex systems requirements, such as increased speed, precision and remote capabilities, bridging the gap between the complex, math-heavy control theory taught in formal courses, and the efficient implementation required in real industry settings. George Ellis is Director of Technology Planning and Chief Engineer of Servo Systems at Kollmorgen Corporation, a leading provider of motion systems and components for original equipment manufacturers (OEMs) around the globe. He has designed an applied motion control systems professionally for over 30 years He has written two well-respected books with Academic Press, Observers in Control Systems and Control System Design Guide, now in its fourth edition. He has contributed articles on the application of controls to numerous magazines, including Machine Design, Control Engineering, Motion Systems Design, Power Control and Intelligent Motion, and Electronic Design News.

• Explains how to model machines and processes, including how to measure working equipment, with an intuitive approach that avoids complex math
• Includes coverage on the interface between control systems and digital processors, reflecting the reality that most motion systems are now designed with PC software
• Of particular interest to the practicing engineer is the addition of new material on real-time, remote and networked control systems
• Teaches how control systems work at an intuitive level, including how to measure, model, and diagnose problems, all without the unnecessary math so common in this field
• Principles are taught in plain language and then demonstrated with dozens of software models so the reader fully comprehend the material (The models and software to replicate all material in the book is provided without charge by the author at www.QxDesign.com)
• New material includes practical uses of Rapid Control Prototypes (RCP) including extensive examples using National Instruments LabVIEW

Section I

Applied Principles of Controls

Important Safety Guidelines for Readers

Chapter 1 Introduction to Controls

Chapter 2 The Frequency Domain

Chapter 3 Tuning a Control System

Chapter 4 Delay in Digital Controllers

Chapter 5 The z-Domain

Chapter 6 Four Types of Controllers

Chapter 7 Disturbance Response

Chapter 8 Feed-Forward

Chapter 9 Filters in Control Systems

Chapter 10 Introduction to Observers in Control Systems

Important Safety Guidelines for Readers

1. Introduction to Controls

2. The Frequency Domain

3. Tuning a Control System

4. Delay in Digital Controllers

5. The z-Domain

6. Four Types of Controllers

7. Disturbance Response

8. Feed-Forward

9. Filters in Control Systems

10. Introduction to Observers in Control Systems

Important Safety Guidelines for Readers

This book discusses the normal operation, commissioning, and troubleshooting of control systems. Operation of industrial controllers can produce hazards, such as:

• Large amounts of heat

• High-voltage potentials

• Movement of objects or mechanisms that can cause harm

• Flow of harmful chemicals

• Flames

• Explosions or implosions

Unsafe operation makes it more likely for accidents to occur. Accidents can cause personal injury to you, your coworkers, and other people. Accidents can also damage or destroy equipment. By operating control systems safely, you make it less likely that an accident will occur. Always operate control systems safely!

You can enhance the safety of control system operation by taking the following steps:

1. Allow only people trained in safety-related work practices and lock-out/tag-out procedures to install, commission, or perform maintenance on control systems.

2. Always follow manufacturer-recommended procedures.

3. Always follow national, state, local, and professional safety code regulations.

4. Always follow the safety guidelines instituted at the plant where the equipment will be operated.

5. Always use appropriate safety equipment, for example, protective eyewear, hearing protection, safety shoes, and other protective clothing.

6. Never attempt to override safety devices such as limit switches, emergency stop switches, light curtains, or physical barriers.

7. Always keep clear from machines or processes in operation.

8. Provide reliable protection, such as mechanical stops and emergency off switches, so that unanticipated behavior from the controller cannot harm you or anyone else, and cannot damage equipment.

Remember that any change of system parameters (for example, tuning gains), components, wiring, or any other function of the control system may cause unexpected results, such as system instability or uncontrolled system excitation.

Remember that controllers and other control system components are subject to failure. For example, a microprocessor in a controller may experience catastrophic failure at any time. Leads to or within feedback devices may open or short together at any time. Failure of a controller may cause unexpected results, such as system instability or uncontrolled system excitation.

This book presents observers, the use of which within control systems poses certain risks, including that the observer may become unstable or otherwise fail to observe signals to an accuracy necessary for proper system operation. Ensure that observers behave properly in all operating conditions.

If you have any questions concerning the safe operation of equipment, contact the equipment manufacturer, plant safety personnel, or local governmental officials, such as the Occupational Health and Safety Administration.

Always operate control systems safely!

Chapter 1

Introduction to Controls

Chapter Outline

1.1 Visual ModelQ Simulation Environment

1.1.1 Installation of Visual ModelQ

1.1.2 Errata

1.2 The Control System

1.2.1 The Controller

1.2.2 The Machine

1.3 The Controls Engineer

Control theory is used for analysis and design of feedback systems, such as those that regulate temperature, fluid flow, motion, force, voltage, pressure, tension, and current. Skillfully used, control theory can guide engineers in every phase of the product and process design cycle. It can help engineers predict performance, anticipate problems, and provide solutions.

Colleges teach controls with little emphasis on day-to-day problems. The academic community focuses on mathematical derivations and on the development of advanced control schemes; it often neglects the methods that are commonly applied in industry. Students can complete engineering programs that include courses on controls and still remain untutored on how to design, model, build, tune, and troubleshoot a basic control system. The unfortunate result is that many working engineers lay aside analysis when they practice their profession, relying instead on company history and trial-and-error methods.

This book avoids the material and organization of most control theory textbooks. For example, design guidelines are presented throughout; these guidelines are a combination of industry-accepted practices and warnings against common pitfalls. Nontraditional subjects, such as filters and modeling, are presented here because they are essential to understanding and implementing control systems in the workplace. The focus of each chapter is to teach how to use controls to improve a working machine or process.

The wide availability of personal computers and workstations is an important advance for control system designers. Many of the classical control methods,...

Table of contents

• Cover Image
• Table of Contents
• Title
• Copyright
• Dedication
• Praise for the new edition
• Preface
• Section I Applied Principles of Controls
• Section II Modeling
• Section III Motion Control
• APPENDIX A. Active Analog Implementation of Controller Elements
• APPENDIX B. European Symbols for Block Diagrams
• APPENDIX C. The Runge—Kutta Method
• APPENDIX D. Development of the Bilinear Transformation
• APPENDIX E. The Parallel Form of Digital Algorithms
• APPENDIX F. Answers to End-of-Chapter Questions
• References
• Index