Distributed Embedded Control Systems

by Colnaric, Matjaz; Verber, Domen; Halang, Wolfgang A.

• ISBN13: 9781848000513
• ISBN10: 1848000510
• Format: Hardcover
• Copyright: 2008-01-28
• Publisher: Springer Verlag

Summary

Very often, practical design of embedded systems lacks consistency resulting in computer control systems that do not provide the performance they should. Most notably they lack dependability, a key property now that programmed electronic devices are so pervasive, even in extremely safety-critical applications.Distributed Embedded Control Systems handles the domains encountered when designing a distributed embedded computer control system as an integrated whole. First to be discussed are some basic issues about real-time systems and their properties, specifically safety. Then, system and hardware architectures are dealt with: areas like scheduling, asymmetrical distributed multiprocessor architectures, time-triggered communications, middleware, fault-tolerant peripherals, etc. Next, programming issues, embodying desired properties, basic language subsets, object orientation and language support for hardware and software specifications and co-design are elaborated and finally, the prototype implementation of a distributed embedded control system is given as a detailed example.Different audiences will find much of interest in this work: industrial professionals are given guidelines for the design of embedded hardware and software with fault tolerance that will help them to decide which methods, tools and solutions they should employ and to which features they should pay attention. Academics have a new source of solutions and further questions to stimulate research and it will also be informative for graduate students in electrical, control and computer engineering.

Author Biography

Professor Colnaric has been involved in real-time research for more than fifteen years. Before that, he worked on practical industrial projects mainly designing embedded operating system kernels and other system software. Most of his research papers, co-authored with Professor Halang, have been practically oriented and some were published in Control Engineering Practice, Real-Time Systems and Annual Reviews in Control. Their book chapters have been published by Kluwer and World Scientific. Following work in the late 90s in embedded computer systems in process control and mechatronic systems he wrote a textbook on digital systems in computing (in Slovene) which is being used in the undergraduate programme of computer science at the University of Maribor. He has authored or co-authored about eighty peer-reviewed contributions to conferences. Professor Colnaric founded and is the current chairman of the Real-Time Systems Laboratory at the Faculty of Electrical Engineering and Computer Science. He teaches courses in real-time systems, digital systems, microprocessors, and data structures and algorithms.Beginning in 1994, he has led several scientific projects financed by Slovenian Government. In the years 2002-2005 his group participated in a 5th FW European project IFATIS dealing with intelligent fault tolerant control, designing and building a distributed embedded platform.Matja++ Colnaric is a member of IFAC and active in its Technical Committee 3.1: Computers and Control. He is one of the four working group leaders, concerned with safety issues. He was a programme committee member for many years, and in the last two years has been the chairman of the IFAC/IFIP/IEEE Workshop on Real-Time Programming, the longest-standing conference in this area (29 years).Professor Colnaric is one of the Editors of the journal Computing and Information Technology published by the University of Zagreb, Croatia, and is an editorial board member of Springer's Real-Time Systems journal and of Oldenbourg's atp International, the new international edition of the well-known German journal of practical automation. Dr. Domen Verber is a member of the Real-time Systems Laboratory and gives the course in microprocessors and is leading laboratory work for students. He has co-authored a number of joint publications and has led a scientific project financed by the Slovenian government.Prof. Wolfgang A. Halang is a well-known scientist in the domain of real-time system design. He is Dean of Faculty of Electrical and Computer Engineering at FernUniversit+ñt in Hagen in Germany. He has (co-) written 7 books, including the Springer titles Genetic Algorithms for Control and Signal Processing and Integration of Fuzzy Logic and Chaos Theory and a very large number of journal and conference papers. He is Editor of Springer's Real-Time Systems journal and is on the editorial board of Multimedia Tools and Applications (Springer), Real-Time Imaging (Elsevier), High Integrity Systems (OUP) and IEEE Concurrency. Professor Halang has also guest-edited numerous journal special issues. He is chairman of the Coordinating Committee of Computers, Cognition and Communications, an important position within IFAC serving on many conference program committees and giving dozens of invited lectures to audiences both industrial and academic. Prof. Halang has rich industrial experience, having worked in the process industry (Coca Cola and Bayer). He holds doctorates in mathematics and in computer science. He has organised a large number of scientific conferences and participated in important scientific and industrial projects.

Table of Contents

Concepts
Real-time Characteristics and Safety of Embedded Systems	p. 3
Introduction	p. 3
Real-time Systems and their Properties	p. 5
Definitions, Classification and Properties	p. 6
Problems in Adequate Implementation of Embedded Applications and General Guidelines	p. 10
Safety of Embedded Computer Control Systems	p. 13
Brief History of Safety Standards Relating to Computers in Control	p. 16
Safety Integrity Levels	p. 19
Dealing with Faults in Embedded Control Systems	p. 21
Fault-tolerance Measures	p. 23
Summary of Chapter 1 and Synopsis of What Follows	p. 28
Multitasking	p. 29
Task Management Systems	p. 29
Cyclic Executive	p. 30
Asynchronous Multitasking	p. 32
Scheduling and Schedulability	p. 34
Scheduling Methods and Techniques	p. 35
Deadline-driven Scheduling	p. 39
Sufficient Condition for Feasible Schedulability Under Earliest Deadline First	p. 41
Implications of Employing Earliest Deadline First Scheduling	p. 45
Rate Monotonic vs Earliest Deadline First Scheduling	p. 46
Synchronisation Between Tasks	p. 50
Busy Waiting	p. 51
Semaphores	p. 53
Bolts	p. 54
Monitors	p. 55
Rendezvous	p. 56
Bounding Waiting Times in Synchronisation	p. 57
Hardware and System Architectures	p. 61
Undesirable Properties of Conventional Hardware Architectures and Implementations	p. 62
Processor Architectures	p. 63
System Architectures	p. 67
Top-layer Architecture: An Asymmetrical Multiprocessor System	p. 69
Concept	p. 70
Operating System Kernel Processor	p. 73
Task Processor	p. 78
Implementation of Architectural Models	p. 82
Centralised Asymmetrical Multiprocessor Model	p. 83
Distributed Multiprocessor Model	p. 86
Intelligent Peripheral Interfaces for Increased Dependability and Functionality	p. 86
Higher-level Functions of the Intelligent Peripheral Interfaces	p. 88
Enhancing Fault Tolerance	p. 89
Support for Programmed Temporal Functions	p. 90
Programming Peripheral Interfaces	p. 93
Adequate Data Transfer	p. 93
Real-time Communication	p. 94
Time-triggered Communication	p. 95
Fault Tolerance in Communication	p. 98
Distributed Data Access: Distributed Replicated Shared Memory	p. 100
Programming of Embedded Systems	p. 107
Properties Desired of Control Systems Development	p. 111
Support for Time and Timing Operations	p. 111
Explicit Representation of Control System Entities	p. 116
Explicit Representation of Other Control System Entities	p. 119
Support for Temporal Predictability	p. 120
Support for Low-level Interaction with Special-purpose Hardware Devices	p. 121
Support for Overload Prevention	p. 124
Support for Handling Faults and Exceptions	p. 124
Support for Hardware/Software Co-implementation	p. 130
Other Capabilities	p. 132
Time Modeling and Analysis	p. 132
Execution Time Analysis of Specifications	p. 135
Execution Time Analysis of Source Code	p. 136
Execution Time Analysis of Executable Code	p. 140
Execution Time Analysis of Hardware Components	p. 141
Direct Measurement of Execution Times	p. 142
Programming Language Support for Temporal Predictability	p. 144
Schedulability Analysis	p. 147
Object-orientation and Embedded Systems	p. 149
Difficulties of Introducing Object-orientation to Embedded Real-time Systems	p. 150
Integration of Objects into Distributed Embedded Systems	p. 150
Survey of Programming Languages for Embedded Systems	p. 156
Assembly Language	p. 157
General-purpose Programming Languages	p. 158
Special-purpose Real-time Programming Languages	p. 160
Languages for Programmable Logic Controllers	p. 163
Implementation
Hardware Platform	p. 169
Architecture	p. 169
Communication Module Used in Processing and Peripheral Units	p. 171
Fault Tolerance of the Hardware Platform	p. 175
System Software of the Experimental Platform	p. 176
Implementation of a Fault-tolerant Distributed Embedded System	p. 181
Generalised Model of Fault-tolerant Real-time Control Systems	p. 182
Implementation of Logical Structures on the Hardware Platform	p. 185
Partial Implementation in Firmware	p. 187
Communication Support Module	p. 188
Supporting Middleware for Distributed Shared Memory	p. 189
Kernel Processor	p. 190
Implementation of Monitoring, Reconfiguration and Mode Control Unit	p. 195
Programming of the FTCs	p. 196
Extensions to MATLAB®/Simulink® Function Block Library	p. 196
Generation of Time Schedules for the TTCAN Communication Protocol	p. 197
Development Process	p. 199
Asynchronous Real-time Execution with Runtime State Restoration by Martin Skambraks	p. 201
Design Objectives	p. 201
Task-oriented Real-time Execution Without Asynchronous Interrupts	p. 202
Operating Principle	p. 203
Priority Inheritance Protocol	p. 206
Aspects of Safety Licensing	p. 211
Fragmentation of Program Code	p. 213
State Restoration at Runtime	p. 220
State Restoration at Runtime and Associated Problems	p. 222
Classification of State Changes	p. 226
State Restoration with Modification Bits	p. 227
Concept of State Restoration	p. 229
Influence on Program Code Fragmentation and Performance Aspects	p. 233
Epilogue	p. 237
References	p. 241
Index	p. 247
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