Competencies of the Department

Control Theory and System Identification - István Vajk

Nowadays control theory and system identification are in their Renaissance age. Substantial growth in the performance of the microprocessor driven devices, the attendance of a new generation of sensors and actuators, further on the enormous evolution in communication facilities in the last decade resulted in a novel class of solutions in control applications. In most applications, control theory has shown up as an invisible but indispensable component in the technology applied. For the public, however, the faulty application of the feedback theorem rises to view only if damages or irregular functional operations are involved.

Due to the increasing capabilities of computer controlled systems, practical applications of rather demanding tasks in terms of processing power have become feasible. This statement is especially valid for estimation and control algorithms based on complex calculations such as eigenvalue/eigenvector calculations, semidefinite programmig (linear programmig, application of linear matrix inequalities, quadratic programming), as well as various polynomial optimization programming techniques. According to the improved environment ready to support applications, researchers are encouraged to elaborate powerful theorems and valuable solutions for a number of open problems in identification, parameter estimation, modelling and control, including stability, analytical solutions and design methods. High performance and robustness properties can be mentioned as related hot issues both in practical and theoretical sense.

To refer to some of the results of the latest years, new algorithms have been developed for the EIV (errors-in-variables) identification allowing the simultaneous estimation of the process and disturbance model parameters. The algorithms are based on the PCA and SVD decomposition in the signal space, respectively. Further on the estimation, procedures working on separated databases deliver the appropriate information for the simultaneous process and disturbance model estimation. Model-based control is considered to be one of the most successful approaches in control nowadays. The department has good experience regarding the application of model-based control in industrial projects. Research was done in robust predictive control algorithms for linear and nonlinear systems as well. Predictive controllers apply the predicted value of the control error to calculate the actual control input. Activity of the control group has been appreciated by setting up a research group sponsored by the Hungarian Academy of Sciences since 1994. We also have held positions to serve in the IFAC. 

power plant

Mobile Software and Service Development - Bertalan ForstnerHassan Charaf

In the last decade the performance and capabilities of mobile devices have increased rapidly. Our group has been participating in this process from the beginning as a research and development partner of device manufacturers (e.g. Nokia), platform developers and operators (Nokia-Siemens Networks, Magyar Telekom, UIQ, IBM etc.). Besides these activities, the group has a leading part to develop the mobile research and application topic further by cooperating with other research centers and designing own innovative solutions.

Yearly hundreds of students participate in our mobile courses. We are proud that our courses cover all mobile platforms in detail )e.g. Android, iOS, Windows Phone, Blackberry and others). The research topics of the group focus always on the hottest topics. Our peer-to-peer file sharing researches and applications based on the research are among the most popular mobile applications. The potential of our multi- and cross platform development proposal - to hide the diversity of the mobile platforms - is increasing more and more. Besides, PhD theses are being formed based on our analytical models related to social networks and location based services. Last but not least, the solutions to decrease the energy consumption of mobile applications have an important role to play in Europe.

COPI - Android

Software Development of Enterprise Systems - István Albert, Hassan Charaf, Gábor Imre

Two platforms dominate in enterprise software environments: Java delivered by Oracle and .NET issued by Microsoft. Our department traditionally keeps good relationships with Hungarian IBM, Oracle, Microsoft, etc. We prepared and performed the home introduction of the .NET platform. In the past decade we have delivered a number of conferences, summer universities, courses, workshops. The MSDN Competence Center was established at our department which continually follows the last technologies and supports home developer community to come to know the novelties.

Industrial projects have substantially assisted the enrichment of our technology knowledge. We have participated in a number of home and foreign software development projects in different roles from business analysis via development to architecture consultancy and project management.

We would like to present the last theoretical results and practical methods to students, which is typical for the philosophy of our department. From 2005, we started an optional subject with the title of Software Design for J2EE Platform. In addition, the laboratories of the Service-Oriented Systems are supported on Java EE platform. The book of the lecturers of our department with the title of Software Design for J2EE Platform is issued by SZAK Publisher throughout the country. The teams related to our department are dominated among the winners of the 48 hour developer championship organized by IBM, which reflects the success of the Java education. We started nationwide first a subject which educates .NET technology with the title of Software Design for .NET Platform. According to the wide interest, a number of subjects can be attended in the topic of .NET: New Generation .NET Technologies, Development of WEB Portals, Software Technologies, Cloud- Based Software Development, Windows Phone 7 -Based Software Development, Game Development of .NET. Hundreds of students study these subjects in each semester, thus, our department plays an important role in training the next generation for Java and Microsoft based technologies.

Both technologies take place in the research area of our department. The Java EE particularly has been used in the field of performance analysis, which was rewarded in the form of IBM PhD Fellowship and Faculty Award. The .NET platform primarily has been applied in order to demonstrate the theoretical results. However, for example, our cooperation with Morgan Stanley has issued successful results in the field of .NET base technology. 

java and .net

Web Application Development - György Balássy, Hassan Charaf

Web portals utilize internet technologies to transfer information to their visitors and support them to complete their tasks. Since only a web browser is required by the user to access the web application, web portals are first class citizens in the world of modern communication infrastructures. An additional benefit is that with the spreading of wireless networks and the evolution of mobile devices, web services become accessible from anywhere, at any time.

There are numerous educational, research and development projects in the field of web development at the Department of Automation and Applied Informatics.

In our education activities, beyond the introduction of modern frameworks, the current questions of web security, performance-centric design, search engine friendly implementation and user friendly interface concepts also get strong emphasis.

Our main research scope is focused on the latest web technology trends, ethical hacking and performance analysis of web applications, in which fields a PhD thesis, several articles, book chapters and presentations were published.

We gain our real world programming experience in industry-leading development projects which we share with our students in regular university courses. Our professionals plan, design, prototype and implement complete software solutions in these projects. Besides, Microsoft technologies (ASP.NET WebForms, MVC, Silverlight) we often use open-source software and emerging new standards, like HTML5 and CSS3, as well.

In the last few years we were invited speakers of numerous industry conferences and most of us are recognized as Microsoft Most Valuable Professionals.


Data Handling Technologies - Renáta Iváncsy, Sándor Juhász, Ferenc Kovács 

Data handling technologies have broad applications since most of the real-world enterprise solutions are based on processing large volumes of data. By having automated data acquisition techniques widespread, the demand for intelligent processing of the large amount data gathered from processes, users and their activities continuously increases. Efficient processing, creation of business statistics and extraction of more information about hidden relationships requires various special techniques.

Our group deals with the following research areas and development projects. During preprocessing, we deal with developing efficient, cache aware storage structures and data handling models to transform the input into a format well fitting to the further processing steps. When dealing with large amount of data we can easily reach the bounds of the main memory, thus there is a need for efficient methods allowing to process large data volumes residing on background storages such as out of core data handling.

The main research area of our group is data mining, especially frequent pattern mining, clustering and classification. A framework called XDataMiner was developed as a test bed for the researches. Furthermore, another framework called KMDM (Knowledge Modeler and Data Miner) is currently under development.

One solution to speed up data processing is to use parallel and distributed algorithms. The main focus of our research is concentrating on exploiting multiprocessor systems and PC clusters to solve the performance issues. To support cluster based solutions and performance, studies a framework called Pyramid was developed by the group.

The information should be presented in a way that makes human understanding simple by adequately visualizing the multidimensional data by multidimensional data visualization methods.

As a result of our researches over the past years, more than 100 scientific papers were issued. 

Industrial and Mobile Robots - Gábor Tevesz

Even though industrial robot manipulators have played an essential role in manufacturing processes for a long time past, the continuous advancement of embedded systems has opened new frontiers for mobile robotics. Keeping up with this emerging field, our department puts emphasis on the education and research of robotic control systems.

Understanding and acquiring engineering skills in the field of industrial robot control is facilitated by modern general-purpose robot manipulators available in our robotics lab. Our master's program offers courses on robot control theory, system architectures and robot programming. Beyond regular courses, our department is conducting research on various topics in robot control. One of our major fields is controlling redundant manipulators of a high degree of freedom which have applications in environments cluttered with obstacles. A number of master's and PhD theses are also connected to 3D robot modeling and investigation of control algorithms. Another important field of research is hybrid motion and force control: industrial manufacturing processes often demand precise motion and interaction with the environment where it is essential to take the forces involved between tool and workpiece into account.

Electrical engineering students participating in our master's program can widen their knowledge and skills within the frames of RobonAUT, an annually organized robotics contest, where students encounter various practical aspects of mobile robotics. Research related to motion planning, localization and mapping in dynamically changing environments is applied by our mobile robot developer team which is designing autonomous mobile robots and participating in the yearly international Eurobot contest since 2003. Beyond competition purposes, these robots facilitate practical testing of results concerning mobile robotic algorithms. 


Modeling, Model Processing - László Lengyel, Gergely Mezei

Model-based software development is getting more and more emphasis nowadays. Apart from documentation purposes, models can be used to express specifications formally. They may be utilized for verification purposes and they can be the source of code generation as well. With the use of models and automated model processors, the reusability and the quality of the developed components can be significantly improved.

The characteristics of a selected application area can be expressed by domain-specific languages to provide efficient solutions to frequently appearing domain-related problems. There is an emerging demand to support domain-specific languages in areas such as corporate workflow systems, power-grid monitoring, industrial robot controlling, and user interface design.

The Visual Modeling and Transformation System (VMTS) is a graph-based, domain-specific (meta)modeling and model processing framework. The system provides a graphical interface for defining, customizing, and utilizing languages. In VMTS, models are given in a visual modeling environment, where the common notation of the domain can be used. Thus, a significant part of the application development can be performed by users without programming knowledge. VMTS provides efficient model processing through its graph rewriting-based and template-based model processing engines.

The modeling environment has been founded by Dr. Tihamér Levendovszky (currently at Vanderbilt University, USA). The application and the underlying scientific background is under constant development and it participates in both academic and industrial projects as well. 


Utilisation of Waste and Renewable Energy Sources - István Nagy, Kálmán Járdán R.

Electric energy systems have been developed that make it possible to utilise energies obtained from waste and renewable energy sources. The basic solution shown in the block diagram converts the energy content of some working medium (steam or gas) first into mechanical then electric energy. The electric energy obtained this way is made usable directly or it can be fed to the mains by an AC/AC converter. The energy fed to the system by the working medium can originate from a steam or gas network during expansion process in the turbine or from renewable energy sources (e.g. solar radiation, geothermal energy, biomass).

The system is suitable for providing additional features utilising the capabilities of the DC link AC/AC converter. These features: Power Factor Correction, including elimination of higher harmonic components and ensuring UPS function can improve the economy of the system by reducing the payback time. The research results connected with the above fields have been realized and published.

The photo on the left of the previous page presents a T-G unit with a rated speed of 12.000 rpm, on the right the cabinet of the AC/AC converter, below an ultra high speed (90 krpm) T-G set can be seen. The specialty of the solution is the application of ultra high speed machines, the induction generator (IG) as well as the realization of the above special features. A significant result was revealing and both theoretically and experimentally confirming a special subharmonic phenomena. A computer simulation result, confirmed also by tests, shows the existence of a subharmonic stator flux of considerable level.

Development of the systems has been carried out within international cooperation by the financial support of the EU. The results were published in two Journal papers and over 50 Conference publications. These results are now part of the University Curricula. Numerous PhD topics, Final projects, Integrating projects in English and successful TDK and OTDK projects have been prepared. 

Nonlinear Dynamics in Power Electronics - István Nagy, Zoltán Sütő

Analyzing nonlinear dynamical systems, understanding their chaotic phenomena and exploring utilization opportunities is an important research trend in many fields. Power electronic systems represent rich source of nonlinear behaviors. One of the main reasons is that the switching time instants depend on state variables. Internationally a very intensive research has been started two decades ago in this area. The Group of Electrical Engineering has joined to this world trend in an early stage. Separated partially from the main line concentrating on the bifurcation phenomena of DC-DC converters but keeping also in mind that in our scope we have achieved results studying three-phase AC-DC or DC-AC converters, mainly related to electric drives. We have reported bifurcation phenomena and chaos in such systems among the first but separately from others.

The nonlinear dynamical studies of simple DC-DC converter topologies have already provided important theoretical results in the classification of border-collision bifurcations, and the bifurcations of smooth systems, for example the period doubling cascade can also be observed. In the piecewise smooth models applied for these systems a single border separates two operating regions with two corresponding state equations. Most power electronic converters, since contain more controlled electronic switches, can be described by models with more than two operating regions. Similarly to DC-DC converters, practical applications of systems containing more electronic switches are extremely wide. Numerous examples can be mentioned for such systems: modern alternating current drives of machine tools, robots, electric vehicles, power quality conditioning, active filtering or even renewable/waste energy recovery circuits are included.

The research primarily targets the comprehension and classification of bifurcation phenomena evolving due to the interaction of more borders contributing to the theory of nonlinear dynamics. At the same time, understanding these complex bifurcation phenomena implies the possibility of devising new practical methods. They can offer faster control with better dynamic performance, more efficient power consumption and lower network pollution. 

Power Converters under the Charm of Green Energy - István Varjasi

Photovoltaic converters and wind power systems applied power converters came into view in the past 10 years with the increasing utilization of renewable energy sources. Being one of the most crucial aspects in the design of renewable energy converters, several hardware and software solutions have been introduced in the recent years which increase conversion efficiency. However next to raising efficiency fulfilling more and more rigorous utility grid connection requirements and standards also have to be taken into account.

Besides efficiency and grid connection requirements, the price of converters and their utilization time determine their suitability for the mass market. The price of the converters is currently about 10-15% of a system connected to the utility grid. Due to the increased focus on PV and wind power converter development, the price of inverters in the small and medium power range (1kW-100kW) decreased by more than 50% in the last decade. The main driving force behind this cut-back are the increasing volumes of mass production and implementation of new control techniques. These new control solutions provide a more cost-effective way and thus their adaption is advisable if compared to possible ways of hardware modifications for reducing system losses - like switching loss in power converters.

The Power Electronics Group of the Department of Automation and Applied Informatics takes part in the elaboration and realization of renewable energy conversion control strategies applicable in industry for years. In respect thereof, great stress is laid upon solar and wind power conversion.

Niveau and acknowledgement of our work are underlined by numerous scientific achievements, successful everyday applications, industrial awards and license acquired patents.

Some of our crucial results from the past years. From the field of solar applications control design and implementation of 250kW, 500kW and 1 MW PV converters for Hyundai Heavy Industries, put into practice 100kW solar inverters for the VHJ Kft, 20kW raised efficiency PV inverter for Exendis have to be highlighted.

From the field of wind power conversion the control system elaboration of a 2.5MW converter for Hyundai Heavy Industries, the development of a 50kW inverter in cooperation with Procon Kft. have to be underlined among others. 

Medical Electronics - Attila Kárpáti

The Power Electronics Group of the Department of Automation and Applied Informatics has a special research and development field namely the development of new generation high frequency X-ray generators and special high voltage circuits for pulse operation mode. Niveau and acknowledgement of our work are underlined by numerous scientific achievements, successful everyday applications, industrial awards and license acquired patents. During our research work in the past years, the main aim was to develop smaller X-ray generators with better parameters. The following guidelines were used during the work. In case of X-ray generators with the increasing of the presently used 50kHz frequency the simplification of the construction of the X-ray generators and the improvement of the dynamic parameters of the tube voltage. The target frequency is a few 100kHz. Therefore, a special converter main circuit with small power loss and a novel control is needed. On the high voltage side the aim is the change of the technology, for example, at the high voltage coils whereupon the production costs and the converter size can be reduced finally resulting in a high power (100 kV/50 kW) portable generator.

The increased switching frequency requires the development of a semiconductor based high voltage and frequency switch (±100kV, 100kHz). For this purpose, currently vacuum tubes are used. The price of the tube is quite high and the lifetime is relatively small. The aim on this field is the improvement of the tube voltage form at the present day generators at short expositions and the replacement of the vacuum tubes in the plasma technology in case of surface coating of a plastic hip prosthesis. Our group is currently working in cooperation with Innomed Medical Zrt on the development of a mobile X-ray family with capacitor energy storage unit and loss optimized control unit in a network friendly circuit design.