Frantisek Zezulka

Virtual Automation Networks

Industrial automation has been dominated by fieldbuses for several decades. Legacy fieldbuses, such as Profibus, were able to provide the required functions, as they were precisely tailored to automation needs. Fieldbuses represent a complex communication solution for automation, and they define automation-specific physical and link layers and a dedicated communication object model. Nevertheless, Ethernet-based communication ubiquitously appearing in offices fostered temptations to bring Ethernet to production. Ethernet provides market-proven cost-effective hardware components with high data rates and immense integration and network management support using the overlaid management protocols. However, Ethernet has not been designed for industrial applications and would fail to fulfill requirements of industrial automation in its generic form. Hence, adaptations in both end devices and sometimes even switching devices had to be carried out. Finally, various industrial requirements were met, and Ethernet-based fieldbuses became state-of-the-art technologies competing with legacy fieldbuses.

Virtual automation networks - architectural principles and the current state of development

This paper deals with principles, architecture and solution to problems of virtual automation networks for purposes of automation. Virtual automation networks represent recent trend of communication in heterogeneous networks in industrial automation. Heterogeneous networks consist of industrial automation systems such as fieldbuses, office LANs, and public networks (Internet and telecommunication technologies). Architectural principles are shown on VAN device profiles and intended network topologies. Salient innovative approaches to industrial automation, such as name-based addressing, integration of Web Services and OpenVPN tunnelling are introduced. Security aspects are paid proper attention for being utmost sensitive in industry. The paper reflects the state of the development of the VAN (Integrated project of the 6th FP) which is being worked on by a consortium of dominant European automation vendors (Siemens, Phoenix Contact, and Schneider Electric), research institutions and technical universities.

Experimental Smart Grid

The paper deals with activities towards a design of a methodology to stabilize already existing electrical grids and at the same time utilize the maximum of electrical energy from renewable electrical energy sources. The authors believe that the first step towards a methodology is to create a thorough model of the electrical grid with connecting most suitable existing renewable as well as classic electric energy sources. There is also described an idea of an experimental smart grid, but the main attention is given to the physical realization of a laboratory model of the smart grid. The authors described an electronic design and an idea of control strategy to enhance a functionality, stability and effectiveness of the grids with a significant share of the renewable energy sources.

Coupling architectures for low-level fieldbusses

This paper deals with hierarchical, multiple fieldbus-based architectures using four case studies that present some concepts reusable in developing the interconnections of intelligent sensors and actuators. The single-master, low-level fieldbusses considered involve (1) ASI (Actuator-Sensor-Interface), which is an example of a lowest-level industrial interconnection; (2) NBIP (Nine-Bit Inter-processor Protocol), which is an example of a special purpose link-layer protocol for microcontrollers; and (3) Bitbus, which is an example of well-established fieldbus utilized for almost 20 years in various applications. The paper begins with classification issues; particularly, coupling architectures are treated both from the viewpoint of more classical interconnections of wide-area and local-area networks, and from the viewpoint of fieldbus domain. Next part introduces the ASI and NBIP protocols while the well-known Bitbus is reviewed in applications. To offer more complex insight, implementation tools-developed particularly to support low-level fieldbus interconnecting experiments-are also mentioned. Four case studies demonstrating consequently NBIP-ASI, ASI-ASI, and two different Bitbus-NBIP hierarchical coupling structures create the kernel of the paper. Finally, brief notes about origins, results, and current targets of the project conclude the contribution.

Trends in Automation - investigation in Network Control Systems and Sensor Networks

Abstract Paper deals with two significant trends in the automation and control theory of the last decade. The problems are evoked by a lack between control theory and the automation praxis in the case of Networked Control Systems (NCS) and by penetration of wireless communication used in case of Sensor Networks. Authors define serious theoretical problems in Networked Control Systems analyses in the design of digital control such as non-periodical sampling period, variable delays in control feedback, lower dependability of feedback information and some other issues. Network Calculus is proposed as a possible mathematical and description tool. The paper also mentions an ambitious research program of the Deutsche Forschungsgemeinschaft to develop new theory of the NCS synthesis. In the second part of the paper the Sensor Networks as the new phenomenon in process values measurement and data acquisition systems are described. It is the opinion of the authors, that sensor networks represent totally other look on the utilization of sensors, than represents classical measurement engineering used in data acquisition systems.

Evaluation of Real-Time Behaviour in Virtual Automation Networks

Ethernet-based fieldbuses continuously penetrate industrial automation and many of them have been standardized (PROFINET, EtherCAT, SERCOS III, etc.). This fact fosters utilization of established Internetworking technologies, such as TCP/IP protocol suites and web services with the aim of widening of the communication scope and seamless interconnection with higher levels of industrial automation. However, industrial applications with their special requirements especially in terms of real-time, functional safety and security call for proper extensions of the existing Ethernet-based fieldbuses. This paper presents state of the art in development of a test bed which will serve for evaluation of real-time parameters of a given point-to-point connection based on the established QoS metrics.

IMMUNE NAVIGATION CONTROL FOR STIGMERGY BASED FORAGING BEHAVIOUR OF AUTONOMOUS MOBILE ROBOTS

Abstract The paper presents a series of experiments in a simulated environment where two autonomous mobile robots gather randomly distributed objects and cluster them into one pile. The coordination of the robots’ movements is achieved through stigmergy (an indirect form of communication through the environment). In order to avoid the drawback of the random moves, necessary for stigmergy based foraging behaviour, the perceptive capabilities of the robots are enhanced by detectors for concentration of objects. An artificial immune network carries out the collision free goal following behaviour. Simulations confirm the improved performance of the foraging behaviour under the proposed immune navigation control.

Energy Sources for an Experimental Electrical Network: PV Panel and Micro-Hydroelectric Power Plants

Abstract The authors present energy sources for an Experimental Electrical Network (E.E.N). The main sources applied are photovoltaic and hydroelectric power plants. For the purposes of modelling the experimental network, the authors describe the measured values of the output power provided by the plants. The performance of the photovoltaic station was measured for the period of three weeks; as expected, the resulting value is strongly dependent on the weather. In the small hydroelectric station, we monitored the relation between the turbine output power and the water level in the weir. Moreover, we also produced a six-hour record of the performance of the station. Based on this characteristic, the relation between the water level and the output power was determined using approximation of the exponential function. The paper also describes the perspectives of remote sensing of the data acquired from a power plant and analyzes the possibilities of storing the data to an SQL server.

Stabilisation of low voltage distribution networks with renewable energy sources

Abstract Recent development in the area of renewable energy sources (RES) shows, that situation in countries supporting a great growth of RES, particularly photovoltaic, leads to big problems. Modelling studies show that in a very near future there will be a big surplus of electrical energy production in networks of NN (low voltage networks). It would evoke necessity to transfer energy into higher voltage networks. However it will not be possible while protection systems of high voltage networks are developed for the opposite flow of energy. Contribution deals with possible solution of stability of NN distribution networks by means of smart metering – smart grid system. Proposal of electronic instrumentation of measurement and control is presented in the contribution.

Interconnecting low-level fieldbusses

Deals with higher-level to low-level fieldbus interconnection architectures, using four case studies that can demonstrate diverse fieldbus coupling techniques. The single-master, low-level fieldbusses considered involve ASI (Actuator/Sensor Interface) and NBIP (Nine-Bit Interprocessor Protocol), while the higher-level fieldbusses are represented, apart from NBIP and ASI in that role, by the well-known Bitbus. Hence, the following interconnections are reviewed: NBIP-ASI, ASI-ASI and two variants of Bitbus-NBIP. This paper discusses some concepts which should be reusable in the development of various low-level fieldbus interconnections that are either dedicated to special-purpose protocols or fit particular operational requirements.