Active Disturbance Rejection Control

Abstract

This book puts in the hands of practitioners, students, and scientists alike, a powerful tool known as Active Disturbance Rejection Control (ADRC).Both the operating principles and ensuing control laws are made fully understandable and easily executable.It addresses real-world control problems where complexity, uncertainty, and physical constraints abound, but solutions must remain simple and transparent.Working at the forefront of technological developments for the past decade, the authors have played an instrumental role in shaping ADRC as a powerful platform for control system design in various sectors of engineering practice.It is with conviction that they set their minds on helping readers find a viable alternative to the century-old, but still dominating, trial-and-error practice of PID (proportional-integral-derivative) control, an alternative that is made both rational and practical in this book.The result is a well-structured book that brings the novices up the learning curve gently and gives the returning readers a source of references and a user's manual.Chapter 2 begins with two physical examples and confronts the readers head-on with the central question: Exactly how much do we need to know about these dynamic systems in order to control them?Hence begins the "first contact with ADRC" and a rendition of ADRC as a paradigm shift in the field of automatic control.Here the style of the narrative is "show, don't tell," allowing readers with some background in college physics and math to follow the narrative in breaking the problems of control and arriving at the core ADRC design principles naturally.Once a reader is engaged, there would be no turning back.Chapter 2 is followed by concrete expositions in the subsequent chapters, as ADRC is generalized to N-th order systems in Chap.3, interpreted and visualized in Chaps.4 and 5, respectively, in both time and frequency domains, and extended and modified in Chap.6 to demonstrate that "ADRC is not a fixed set of equations," but "a modular, flexible framework that could be tailored to specific applications."Part I (Foundations) of the book ends in Chap.7, which provides the overview of this active field of study and the bridge to Part II (Going Practical).Going practical, indeed!Covered in less than 50 pages, from Chaps.8-10, are digitizing ADRC in both state space and transfer function forms, arranging bumpless transfer from one to another controller, dealing with physical imperfections such as actuator saturation, v vi Foreword noise and deadtime, etc., and arriving finally at software implementation in Matlab/Simulink or C language directly.The key here is self-containment: practically it is all here for a user to try his/her hands on ADRC and solve real-world problems, as it is shown in Chap.11.In fact, the book doesn't have to be read sequentially.For example, readers may jump to Part II and do a quick proof of concept validation using the examples there, with the recipe-like procedures implemented in C codes or Simulink blocks.And then return to Part I for better understanding of the principles behind.Note that these procedures are collected as a whole in the final chapter for quick references, along with authors' outlook for ADRC as the tool of choice in the future.Finally, I want to thank the authors personally for their dedication and unselfishness in writing this go-to book for a wide range of audiences.It is a distinct privilege of mine to witness their professional growth both as scholars and practitioners, a rare combination in itself, for more than a decade.They did a great service to the field of control engineering with this book by providing a pragmatic, self-contained introduction to ADRC, where principles and practices are intimately connected.They made every attempt to make the book reader-friendly, understandable by all, and plug-and-play ready.What they didn't cover in this compact book of fundamentals, such as the subject of rigorous mathematical analysis, they provided an overview of the landscape and references for further readings in Chap.7.

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