[PDF] WirelessHART Filter Design for Industrial Wireless Networked Control Systems

Industrial wired communication protocols such as highway addressable remote transducer (HART), Foundation Fieldbus, and process field bus (PROFIBUS) have been in industries for more than 25 years. Recent advances in wireless technology have led to the emergence of international industrial wireless standards such as wireless HART (WirelessHART) and ISA100 Wireless (formerly known as ISA100.11a) that are specifically designed for industrial monitoring and control applications. The introduction of these technologies has allowed the process industries to move forward in applying them to solve some of the critical issues associated with the wired protocols such as high operation cost and low installation flexibility. At present, their main application is for monitoring process parameters while several attempts are being made for control. This is mainly because of the two major technical challenges: network induced delays and packet dropout (loss) which contribute significantly to the
degradation of control performance of wireless process plants.

In order to address these issues, model-based approaches using Smith predictor and Kalman filter have been considered. However, they are complex, model-dependent, and not computationally efficient for use in low processing capability microcontroller-based field actuators. In an industrial environment, long battery life is required for these actuators, and the model-based techniques cannot satisfy this requirement.

Therefore, to tackle these two challenges, this book aims to introduce an
advanced dual purpose exponentially weighted moving average (dpEWMA)
filter which is simple, model-independent, and more computationally efficient than traditional filters. The filter can be implemented in any type of microcontroller without severely affecting its energy consumption. In addition, by applying the designed filter, the negative effects of network induced delays as well as packet dropouts on plant control performance are compensated. Being generic is another advantage of the filter; thus it can be applied to address the issues across industrial networked control systems, regardless of communication medium such as wires or wireless. In addition, this book also details the development of WirelessHART hardware-in-the-loop simulator (WH-HILS) that is suitable for use as a scalable validation platform for any wireless control strategies using the industrial WirelessHART technology.

This book will be of particular interest to process control engineers, especially those working towards migrating their plants from a wired to a wireless network. Other possible beneficiaries of the content of this book are researchers and students studying delay and packet dropouts compensation in a wireless networked control environment. This is specifically made easy by the use of
WH-HILS.

With a total of 11 chapters, the book is structured in such a way that
sequential flow is maintained. Thus the readers of the book will find it interesting since each chapter builds on the preceding chapter. For example, Chapters 1 and 2 give the introduction to general wireless technologies and WirelessHART. This includes the recent work being done in both simulation and practical environments. Chapters 3 and 4 discuss the challenges of the uncertain nature of wireless networks including delay and packet dropout and approaches for measurement of these entities. Next, Chapter 5 discusses in detail the essential delay and packet dropout compensation techniques. Furthermore, Chapters 6 and 7 cover the fundamentals of EWMA filters and advanced design of the dpEWMA filter for addressing the negative effects of both delay and packet dropout in wireless networked control systems. The remaining chapters (8, 9, 10) focus on the implementation of the designed filter for both wired and wireless industrial-like control environments and assessing its performance. Finally Chapter 11 presents some interesting directions for
future investigations and continuation of the presented works.