Witold Nocoń

Multi-Agent System for Hierarchical Control with Self-organising Database

The paper presents hierarchical and multi-agent control and information system with real-time update of self organising database as well as with negotiation capability for control events and decisions. A practical application is presented, that utilizes the OPC technology in the continuous-time part, and scripts using XML in the discrete-time part of the system for negotiation and cooperation in multi-agent environment. This feature is applied for the improvement of a non-conventional biotechnological process control in the pilot plant.

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.

Mathematical modelling of distributed feed in continuous sedimentation

Abstract One-dimensional modelling of continuous sedimentation process is considered in this paper. The process is described by a scalar conservation law in the form of a partial differential equation. A new way of modelling the feed section of the continuous settler is proposed. Unlike other models, the proposed model upon discretisation incorporates a greater number of layers in the feed section of the settler. The results obtained with the proposed model are presented and a comparison is made between the proposed distributed source model and the traditional (and widely accepted) point source model that includes only one discretisation layer in the feed zone. It is shown that the obtained values of steady-state effluent and underflow concentrations are identical. The differences in transient states and in steady-state solutions are shown and discussed.

Application of the Holonic Approach in Distributed Control Systems Designing

Design of a multidisciplinary project is a complicated process requiring cooperation of different designers specialized in particular branches of engineering. The paper proposes a holonic approach to testify that a solution of distributed control systems is compliant with dynamically changing technology rules with ontology-based decomposition. The proposed holarchy includes a multi-agent system considering also its hybrid control architecture connected with a self-organization database. The proposed approach was implemented for a biotechnological pilot-plant continuously working as a platform for several process investigations.

Multiscale Three-Phase Flow Simulation Dedicated to Model Based Control

Multiphysics and multiscale three-phase flow simulation is proposed for model based control. Three-phase flow is considered by means of particles movement in a pipe with two-phase gas and liquid vacuum pumping. The presented model and simulation algorithm were implemented using a software system working in real-time mode. The software system can simulate a part of the pipe net with configured pipe profile, pump station and valve parameters and also inlet mixture composition. In addition, the system includes algorithm for pressure control.

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.

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.

MAS-Based Cooperative Control for Biotechnological Process-A Case Study

The MAS-based control seems to be better suited for manufacturing control because of its discrete event character. Nevertheless, for continuous industrial processes the MAS-based control can be also very attractive. In this paper, a synthesis of the MAS-based control system for the continuous process is presented. A biological reactor is controlled using respirometric approach. In this approach, both standard control loops and additional experiments are performed to obtain measurements not available on-line. Therefore, the system consists of different control agents being able to cooperate or to inhibit each other in order to achieve the appropriate goals. A case study experiments are realized using an experimental wastewater treatment pilot plant.

Object-Oriented Framework for Cooperative Testing of Control Algorithms for Experimental Pilot-Plants

In this paper a framework for cooperative testing, implementation and learning of control algorithms for the purpose of controlling experimental pilot-plants is presented. It is based on the principles stated in the IEC61499 standard. The proposed framework enables modification of the control algorithm structure without rewriting the main software component executed on the programmable automation controller PAC. Functions realized by particular blocks may be changed dynamically during the runtime. The framework is implemented in LabVIEW enabling implementation of algorithms containing advanced analysis functions and complex control algorithms by multiple users, providing an effective practical group support system.

Decomposition of Information for Plant Collaborative Design and Set-Up

A problem of coordinating engineers working in different fields during design and control of an industrial installation is especially difficult during start up and modification of the process. Any work carried out in such a case must be coordinated in real time. Moreover, level of access to information is differentiated for different branches of engineers. In this work a hybrid agent-based system for cooperative plant design and set up of the biotechnological pilot plant is proposed. The major contribution deals with decomposition of biotechnological plant information by hybrid agent system for enhancing cooperation of experts having different knowledge about the process. Hybridization of the process is performed considering nine states, while estimation of the information distance is performed based on partial Kullback-Liebler cross-entropy function. Experience gained during design and exploitation of the mentioned biotechnological pilot-plant suggests this solution to be promising.