Measuring real time performances of PC-based industrial control systems

This paper discuss on how to develop a hard real-time machine control system with Microsoft Windows NT Operating System, where the respond must be within 0.5 milliseconds. The attempt to use a general-purpose operating system (Microsoft Windows NT 4.0 Workstation) is because there is abundance of Commercial-Off-the-Shelf Components (COTS), easily available tools (compilers, and 3 party tools) and need not to learn another operating system behavior. The most important factor is there is no single dominant operating system or tools vendor for real-time operating system. Since the no single dominant real-time operating system development under real-time operating system is riskier and more costly. Ideally codes must be portable between different operating system where it is apparent with Windows platforms, Windows 95/98, Windows ME, Windows 2000, Windows XP or even Windows CE. Firstly study was done on how Microsoft Windows NT operating system works internally from materials from Microsoft Software Development Network (MSDN). Secondly study was done how to take advantage of the operating system to create a real time application. Microsoft Windows NT is a general purpose operating system that does not support real time application development, but it has all the vital elements that a real time operating system needs. The vital elements are priority-driven, preemptive scheduler, preemptive interrupt handler (for critical interrupts), deferred procedure calls (DPC) for non-critical (DPC executes after ISR), synchronization and deterministic response time. With these vital elements and some modification to application codes to enable it to execute in higher priority level, would result a real time application. This does not mean changing all the codes to higher priority is the solution, as it would cause system to malfunction as other device driver or low-level interface run at high priority too and this would lock up the system. With the combination of priority level, synchronization a complete real time solution can be implemented and this paper covers the concept. This concept also explains what was done to overcome the need of special hardware (as recommended) to accomplish hard real-time application with the response of 0.5 milliseconds.

The core idea in this project is to have two operating systems for both cores of dual core processor individually. General purpose operating system on one core and Real time operating system (RTOS) on second core. Implementation of same will be done by making one of core independent from General purpose operating system and install RTOS in that core so that both will work as one system i.e. General purpose operating system will look after the non-real time applications and RTOS will ensure that all real time application should not miss their deadline and executed as fast as they can. As by installing general purpose operating system and RTOS in both the cores of dual core processors of system and running them in parallel way, dual core processors is being used to its maximum efficiency. The advantage is that if one of OS gets crashed, whole system will not crash instead one of OS which didn't crash hold the system to safe mode till damaged OS is recovered.

This paper investigates the possibilities of using virtualization in multicore real-time embedded systems based on combination of general-purpose and real-time operating systems running on separate processor cores. The research is focused on ARM processor architecture due to its widespread usage in numerous application domains. The paper describes the concepts and practical considerations of using virtualization to achieve better interrupt latency both in Linux, as a typical representative of commonly used general-purpose operating system in applications requiring real-time response, and real-time operating system running on separate cores. In the proposed approach we demonstrate how to use virtualization mechanism to decouple cores responsible for real-time and non real-time tasks in a multiprocessor system with real-time requirements. Xen Hypervisor is used as a virtual machine monitor with default credit and new experimental null scheduler. The aim of research was to study the system response time characteristics and to assess practical usability of such approach in applications with hard real-time requirements.

In this paper we present a software tool, developed using Matlab, that serves as an instructional aid for learning the design of ratio control systems for industrial processes. The tool considers both the series and the parallel control structure and enables the user to tune the parameters of the two PID controllers, as well as subsequently evaluating the impacts of these alterations. The evaluation of the set-point and load disturbance step response, along with the filtering of measurement noise, can be conducted. It is thought that this software has the potential to be effectively utilized in process control courses, facilitating a deeper comprehension of the practical application of theoretical concepts given by the instructor. An illustrative example is given in this context.

Internet-based control systems have been evolving rapidly in recent years. Using Web-based technology, control systems have been shown to have an increasing potential for remote control, industry process control system. In order to improve the industry process system performance affected by Internet-induced variable time delay, this paper carries on a plenty of test: (1) analyzes its statistic characteristics; (2) adopts the modified Elman NN to predict uncertain Internet time-delays; and, (3) applies to adaptive Smith compensator to improve the system dynamic performance and remain system's stability. The experimental tests show that this method improves greatly the forecast precision and system's dynamic performance.

An architecture for metamorphic control of holonic manufacturing systems

In recent years, the number of invested resources adopted in experiments of embedded applications dropped significantly as many simulation technologies are widely used. However, the efficiency of simulations is seriously influenced by some expensive and difficult-to-obtain devices. It is urgent and of great significance to build a universal simulation platform for embedded applications on general-purpose operating systems with an objective of improving the efficiency and effectiveness of system development and implementation. Since virtualization technology can greatly enhance the simulation efficiency by providing virtual models to simulate the behaviors of real devices, this paper designs and realizes a real-time simulation platform on general-purpose operating systems with the virtualization technology such that embedded applications would be correctly and efficiently debugged and tested on the general-purpose operating systems. The proposed simulation platform contains four layers named hardware resource, virtualization, virtual runtime environment, and interface adaptation, allowing dynamic debugging and testing of embedded applications without requiring the actual presence of real devices. Experiments are conducted to verify the functionalities of the proposed simulation platform, and results demonstrate that the proposed simulation platform can meet the real-time and high reliability requirements of embedded applications.

In the movie Matrix, our hero Neo must choose between taking the Blue Pill and continuing to live in an online, synthesized fantasy world, or taking the Red Pill and joining the real world. The fantasy world appears to those living in it to be full of flowers and trees and big steak dinners, but unknown to them contains malicious Agents who can alter any portion of the world to suit their needs. The real world, in turn, while real, has no visible sun, and the people have only gray mush for food.Authorization and authentication of online transactions across a network requires a trusted path between the user and the server. We posit that those who attempt to solve this problem by creating the trusted path on the general-purpose operating system have taken the Blue Pill and are living in a fantasy world. One simply cannot properly secure a general-purpose operating system.Solving the problem by taking the Red Pill and completely replacing currently used operating systems with ones that we can properly secure does not seem palatable. We suggest a solution that involves taking both the Blue Pill and the Red Pill: providing the trusted path by means of a separate device with a secure operating system, used in tandem with the existing general purpose operating system. Most user interaction occurs on the un-trusted system, with the secure device only being used to finalise transactions.We believe that the technology required for such a device is readily available. Obviously our idea is not a completely novel idea; prior work in the area has had a similar goal. However, most of those attempts have not properly addressed the requirements for the trusted system, generally preferring to use existing general-purpose systems even when on a dedicated [Balfanz 1999] [Kingpin 2001] Others have a very limited scope of use. [Blakely 2004].We identify a minimum set of requirements for the trusted device. This paper does not provide a working solution (it is a position paper after all); we simply define how one should approach that working solution. Because we advocate a hybrid system it is possible to simplify the trusted system to a point where it would not be usable as a general purpose system, which should make the trusted system rather easier to build and have confidence in.

6 - Operating Systems

Describes OFTT (OLE Fault Tolerance Technology), a fault tolerance middleware toolkit running on the Microsoft Windows NT operating system that provides the required fault tolerance for networked PCs in the context of industrial process monitoring and control applications. It is based on the Microsoft Component Object Model (COM) and consists of components that perform checkpoint-saving, failure detection, recovery and other fault tolerance functions. The ease with which this technology can be incorporated into an application represents the primary innovation. It is hoped that, by making fault tolerance more compatible with standard software architectures, more reliable PC-based monitoring and control systems can be built conveniently.

Real time control of holonic manufacturing systems requires a radically different approach from that of traditional unit level regulatory control. Because they need to automatically adapt and reconfigure based on the ever changing requirements of the manufacturing system, control systems based on this approach are termed metamorphic control systems. The engineering of such software centric metamorphic control systems for dynamically reconfigurable distributed multi sensor based holonic systems is addressed. An integrated and uniform event driven control architecture is specified for various functional levels of metamorphic control system. This architecture utilizes the emerging International Electrotechnical Commission function block standard (IEC 1499) for industrial process measurement and control systems to specify the requisite behavior of distributed control software components (agents).

The characteristics and applications of the system for welding machines based on SCM , based on PLC control system and PC-based industrial control system was introduced. It has certain significance to the design of welding machine control system.

This book presents a synthesis of recent works concerning reactive system design. The term `reactive system' has been introduced in order to avoid ambiguities often involved with the term `real-time system' which, while being best-known and suggestive, has been assigned so many different meanings that it is almost inevitably misunderstood. Industrial Process control system, transportation control and supervision systems, signal processing systems, etc. are examples of the systems we have in mind. Four programming languages are presented, which share the same underlying synchronous model: based on Robin Milner's pioneering works about synchronous process algebras, this model consists in considering that a program instantaneously reacts to events, or that the machine execution time is negligible with respect to the response delays of its environment. Using this abstract point of view, the time behavior of a system can be formalized in a very simple and elegant way. The languages presented are ESTEREL, a textual imperative language; ARGOS, a graphical language inspired by STATECHARTS; and LUSTRE and SIGNAL, two declarative languages. After a tutorial description of the languages, illustrated by various examples, a set of related tools is presented: compilers to sequential and distributed code, silicon compilers, verification tools.

The IGEM (Industrial Global Environment Manager), which is a real-time operating system with ITRON specifications, has been developed and applied to the mobile radio communication systems. This system is used for AVM (Automatic Vehicle Monitoring) and MCA systems (Multi Channel Access) which uses M68000 (MCP-16 board) CPUs, having several connections to more than one microcomputer. In this system, a general purpose operating system (OS-9)* and real-time operating system (IGEM) coexist,and they work together. This paper introduces examples of the use of this system and gives an evaluation of its operating system.

Chapter 6 - Protecting Critical Infrastructure: Process Control and SCADA