Grzegorz Polaków

Holonic Multiagent-Based System for Distributed Control of Semi-industrial Pilot Plants

Semi-industrial pilot plants are the best experimental domain for advanced control systems testing with the real-world instrumentation. At the same time, inexpensive flexible process real-time simulators and virtual soft controllers are indispensable in the research and education field. Integrating control instrumentation of varying manufacturers, plant simulators, and virtual controllers into uniform system capable of flexible research and educational experiments is a complex problem to solve. A tool is needed to describe and organise knowledge on such integrated structure involving many communication channels and using distributed processing power. In the presented case-study, holarchy paradigm is applied, resulting in an untypical holonic multiagent system. The concept, architecture and development of application framework for the system are presented thoroughly in the paper.

Cooperative validation in distributed control systems design

The team of engineers designing and implementing distributed control system software must communicate within a multidisciplinary environment. One of the main problems is the interaction between hardware and software solutions. Software project presumptions may not be based only on minimum hardware requirements and on technology rules. Modern distributed control systems embrace all aspects of a complex and widespread object. Hence, every modification within any discipline requires interference into the system and validation of its new features, which in turn constraints effectiveness of designing. This paper discusses how to increase effectiveness and speed up validation, in a standardised CAD environment, by using: Multi-Agent System in order to limit the number of interactions between particular subsystems, ontology for assisting topology description and properties of system entropy for assessment of introduced solutions. The proposed system was implemented and worked out in a biotechnological pilot plant.

Agent---Based Approach for LabVIEW Developed Distributed Control Systems

Idea of networked software agents is particularly popular in the field of information sciences dealing with distributed content, whereas in industrial automation its use is usually limited to manufacturing systems. This work presents a concept of multi---agent networked system for automation of continuous processes. Some properties of typical software agent (i.e. advanced high level languages and social skills) had to be dropped in exchange for determinism and satisfying time performance in negotiations between network---connected control components. The proposed environment is National Instruments LabVIEW, very popular solution for automation and measurement. LabVIEW is equipped with advanced data acquisition tools and is capable of artificial intelligence methods, although it lacks agentification mechanisms. A framework is presented, providing LabVIEW the required functionality.

Performance evaluation of the parallel processing producer-distributor-consumer network architecture

The CSMA/CD access method is no longer invoked in switched, full-duplex Ethernet, but the industrial protocols still take the presence of the method into account. The parallel processing producer-distributor-consumer network architecture (ppPDC) was designed specifically to actively utilize the frame queuing. The network nodes process frames in parallel, which shortens the time needed to perform a cycle of communication, especially in cases when frame processing times within the nodes are not uniform. The experiments show that the achievable cycle times of the ppPDC architecture are an order of magnitude shorter than in the well-known sequential PDC protocol.

Agent-Based Framework for Distributed Real-Time Simulation of Dynamical Systems

A framework is presented, supporting calculation tasks specific to the control theory, allowing for a consolidation of theory-based calculations with real-world control systems by means of hardware sensors and actuators. A networking protocol was designed specifically for this task, employing producer-distributor-consumer data distribution scheme over Ethernet network to enable synchronised execution of spatially distributed mathematical models implemented as intelligent blackboard-based agent system, in order to properly cooperate with sampled real-world continuous dynamical systems. Comprehensive data on internal structure of distributed system is available by monitoring web service, so it is possible to integrate frameworks output in other software.

Cooperative Access to Hierarchical Data from Biotechnological Pilot-Plant

A hierarchy of data is dependent on the level of its complexity and on the amount of knowledge needed for its interpretation. Cooperation between users of the data at different levels of hierarchy requires development of plans to access the data for individual users depending on their needs. Such plans can be built basing on the common field of experience notion. The work presented in the paper focuses on increasing the cooperation efficiency through the use of a social bookmarking system maintaining the unambiguity of hierarchical knowledge structures. Lack of such structures would significantly impair the cooperation process. The proposed multiagent system contains ontologies for classifying non-hierarchical components and enables the exchange and comparison of the data structures. Thus, tags associated with the graph-based rules of social bookmarking can be classified using strict hierarchical terms. Presented solution was evaluated by supporting microscopic observations during experimentation on biostimulation of biological wastewater treatment process.

A Study on Appropriate Plant Diagram Synthesis for User-Suited HMI in Operating Control

In this paper a study on appropriate plant diagram synthesis for user-suited HMI in operating control is presented. Discussion is based on the long-term personal experience and illustrated with excerpts of existing HMIs developed for research and industrial use. The HMI notion is defined for operating control and for operator training. The paper present three aspects of plant diagrams design. The first aspect deals with task-oriented usage of screen space for plant diagram and other GUI elements. Second aspect covers all methods of image creation for process diagrams, including photography, schematic diagrams, use of predefined normalised 3D graphical elements, and creative possibilities of 3D scene. The third aspect stresses capability of dynamic visualisation with the use of animated graphics.

Cooperative Internet-Based Experimentation on Semi-industrial Pilot Plants

In this work a framework for cooperative experimentation with semi-industrial pilot plants is presented. A software solution designed to support multi-user cooperative experimentation is described, along with the supporting hardware, which was specifically designed for the task. A structure of dual networking is proposed, with horizontal real-time protocol for hardware integration and vertical multi-user access points for human interaction. To avoid potential conflicts between users, prioritisation is performed, as resources available (time, hardware, and data) are limited. An important sub-problem is described in details, i.e. large groups of students splitting into smaller subgroups, collaboratively performing partial experiments in order to achieve solution of problem stated by an instructor. Work and data flows have to be carefully designed to keep control of the collaboration an example of such schedule is provided and described.

LabVIEW based cooperative design for control system implementation

In this paper an object-oriented approach to the cooperative process of designing and implementing control systems is presented. Such approach promotes code reuse, code encapsulation and polymorphism, which, in relation to control systems, result in a better way of designing the system to be robust, easy to maintain and clear to analyze. Class hierarchy of system blocks and variables is presented using UML class diagram. Implementation in a graphical programming language LabVIEW is outlined.

Web-based visualization of student cooperation during distributed laboratory experimentation

This work addresses the problem of visualizing hardly formalized relations i.e. connections between distributed collaborating experimenters. These dependencies are not measurable and hard to determine. It is proposed to determine the relations using the measurable and determinable connections between software agents acting on behalf of the users. A connection between the agents is treated as the proof for relation between their owners. A method of system structure data acquisition is proposed, which consists of capturing and interpreting the communication traffic between the agents. The content of the traffic is analyzed and presented in formalized form, according to the developed XML Schema. An example of graphical visualization is provided, presenting the mesh of inter-user relations as an interactive graph. An automated spatial clusterization of the graph components is performed, resulting in optical information on the current state of collaboration.