Jacek Szklarski, Ph.D.

Department of Intelligent Technologies (ZTI)
Division of Intelligent Systems (ZeSI)
position: assistant professor
telephone: (+48) 22 826 12 81 ext.: 221
room: 439
e-mail: jszklar

Doctoral thesis
2007-12-19Helical magnetorotational instability in MHD Taylor-Couette flow  (Uni-Postdam)
supervisor -- Günther Rüdiger, Uni-Postdam
1231
 
Recent publications
1.Szklarski J., Planowanie scenariusza eksploracji w grupie wzajemnie obserwujących się robotów, PRACE NAUKOWE POLITECHNIKI WARSZAWSKIEJ, SERIA: ELEKTRONIKA, ISSN: 0137-2343, Vol.1, No.195, pp.279-288, 2016
Abstract:

Jedną z zalet systemów składających się z wielu robotów mobilnych jest możliwość współdziałania jednostek w celu zwiększenia dokładności ich samolokalizacji. W artykule omówiono sytuację, w której zakłada się że roboty praktycznie nie mają dostępu do czujników pozycji bezwzględnej i swoją pozycję ustalają jedynie na podstawie czujników proprioceptywnych, wzajemnych obserwacji oraz -- opcjonalnie -- obserwacji pojedynczego znacznika, co umożliwia osadzenie pozycji w układzie globalnym. Na przykładzie problemu kooperatywnego przeszukania obszaru, poprzez przeprowadzenie symulacji, pokazano że odpowiednie zaplanowanie trajektorii pozwala w istotnym stopniu zwiększyć dokładność pozycjonowania.

Keywords:

planowanie ścieżki, systemy wielorobotowe, wzajemne obserwacje

Affiliations:
Szklarski J.-IPPT PAN
2.Chechliński Ł., Kogucik D., Białek Ł., Szklarski J., Borkowski A., Integracja Planera zadania Search and Rescue z fizycznym systemem wielorobotwym, PRACE NAUKOWE POLITECHNIKI WARSZAWSKIEJ, SERIA: ELEKTRONIKA, ISSN: 0137-2343, Vol.1, No.195, pp.235-244, 2016
Abstract:

Niniejszy artykuł opisuje prace wykonane w celu przeprowadzenia eksperymentu weryfikującego działanie Planera zadania Search and Rescue na zespole trzech robotów kołowych w budynku użyteczności publicznej. Celem zadania jest przeszukanie obiektu przez grupę robotów, odnalezienie w nim poszkodowanych oraz wezwanie pomocy w odpowiednie miejsce. Punktem centralnym systemu jest Planer wykorzystujący język logiki czterowartosciowej 4QL, który został uprzednio przetestowany na symulacjach komputerowych. Jego działanie zostanie opisane pobieżnie, głównym tematem jest metodyka wdrożenia. Aby przeprowadzić eksperyment, należało zintegrować Planer z systemem wielorobotowym. Wedle autorów jest to zadanie nietrywialne, dlatego przy jego realizacji wykorzystano paradygmaty Test-driven development (TDD), zaadaptowane odpowiednio do realiów robotyki mobilnej. Finalny eksperyment został nagrany, a wideo udostępniono w Internecie.

Keywords:

logika wielowartościowa, search and rescue, systemy wielorobotowe

Affiliations:
Chechliński Ł.-Warsaw University of Technology (PL)
Kogucik D.-other affiliation
Białek Ł.-University of Warsaw (PL)
Szklarski J.-IPPT PAN
Borkowski A.-IPPT PAN
3.Szklarski J., Wikło M., Designing of Elastoplastic Adaptive Truss Structures with the Use of Particle Swarm Optimization, MATHEMATICAL PROBLEMS IN ENGINEERING, ISSN: 1024-123X, DOI: 10.1155/2015/652824, Vol.2015, pp.652824-1-14, 2015
Abstract:

In the paper we demonstrate how Particle Swarm Optimization (PSO) can be employed to solve the Adaptive Impact Absorption (AIA) problem. We consider a truss structure which is subjected to impact loads. Stiff bars can be replaced by elastoplastic fuses which control theirs dynamical response. The point of optimization is to maximize or minimize a given objective function by redesigning the structure. This is realized by redistributing the initial mass, finding proper fuse localizations and adjusting, in real-time, the elastoplastic limits. Comparing to the previous results, we show that PSO is capable of achieving results at least as good as gradient-based optimization, having at the same time much larger flexibility regarding the definition of the objective function. This gives significantly broader field of potential applications. In particular, we present how PSO can be used to solve the simultaneous optimization problem: mass redistribution and fuse positioning for a set of expected, various impacts.

Keywords:

adaptive impact absorption, particle swarm optimization, truss structures

Affiliations:
Szklarski J.-IPPT PAN
Wikło M.-other affiliation
4.Gawron P., Pawela Ł., Puchała Z., Szklarski J., Wybory samorządowe 2014. W poszukiwaniu anomalii statystycznych, Studia Wyborcze, ISSN: 1898-0082, Vol.9, pp.53-77, 2015
Abstract:

W pracy przeanalizowano dane liczbowe dotyczące wyników wyborów do sejmików wojewódzkich, które odbyły się w Polsce w listopadzie 2014. Badania korelacji pomiędzy frekwencja wyborczą, odsetkiem głosów nieważnych oraz wynikami danego komitetu wyborczego, a także porównanie częstości występowania poszczególnych cyfr w wynikach wyborczych z prawem Benforda nie wykazały oczywistych anomalii statystycznych, które mogłyby dostarczyć argumentów za tezą o masowych nieprawidłowościach lub oszustwach. Z drugiej strony porównanie wyników wyborów z lat 2010 i 2014 oraz analiza modelu matematycznego symulującego zarejestrowane wyniki pozwala potwierdzić „efekt pierwszej strony”: głosowanie za pomocą broszury wyborczej mogło przynieść wymierne korzyści komitetowi wyborczemu, który w wyborach wylosował numer 1.

Keywords:

wybory samorządowe, analiza statystyczna, prawo Benforda, efekt pierwszej strony

Affiliations:
Gawron P.-Institute of Theoretical and Applied Informatics, Polish Academy of Sciences (PL)
Pawela Ł.-Institute of Theoretical and Applied Informatics, Polish Academy of Sciences (PL)
Puchała Z.-Institute of Theoretical and Applied Informatics, Polish Academy of Sciences (PL)
Szklarski J.-IPPT PAN
5.Typiak A., Gnatowski M., Szklarski J., Creating terrain maps for unmanned ground platform, SOLID STATE PHENOMENA, ISSN: 1012-0394, DOI: 10.4028/www.scientific.net/SSP.210.32, Vol.210, pp.32-39, 2014
Abstract:

A typical unmanned and remotely operated platform is usually equipped with cameras which give insufficient information about the nearest environment and an operator has difficulties in driving such a platform in unknown environment. In this paper, a problem of the platform nearest area map building based on additional devices is considered. The platform is equipped with SICK LMS lasers, inclinometer and radars. Combining information from the devices allows to build a map which helps an operator to drive the platform more efficiently.

Keywords:

3D Map Building, Laser Telemeter, Navigation System, Surroundings Recognition, Unmanned Ground Platform

Affiliations:
Typiak A.-other affiliation
Gnatowski M.-IPPT PAN
Szklarski J.-IPPT PAN
6.Białek Ł., Szałas A., Borkowski A., Gnatowski M., Borkowska M.M., Dunin-Kęplicz B., Szklarski J., Coordinating multiple rescue robots, PRACE NAUKOWE POLITECHNIKI WARSZAWSKIEJ, SERIA: ELEKTRONIKA, ISSN: 0137-2343, Vol.1, No.194, pp.185-194, 2014
Abstract:

The paper reports initial results on modeling and simulating cooperation of rescue robots. Our aim is to investigate the efficiency of the “first simulate then act” paradigm for rescue operations undertaken by multiple mobile robots, assuming that information about the environment can be incomplete and partially inconsistent. To deal with ignorance and contradictions we adopt a non–standard logic in the inference engine. To demonstrate feasibility of our approach we present the architecture of the developed simulator and results of experiments done so far.

Keywords:

four-valued logic, search and rescue, multirobotic systems

Affiliations:
Białek Ł.-University of Warsaw (PL)
Szałas A.-other affiliation
Borkowski A.-IPPT PAN
Gnatowski M.-IPPT PAN
Borkowska M.M.-IPPT PAN
Dunin-Kęplicz B.-other affiliation
Szklarski J.-IPPT PAN
7.Szklarski J., Arlt R., Nonlinear simulations explaining Ap star magnetic fields by instability remnants, ASTRONOMY AND ASTROPHYSICS, ISSN: 0004-6361, DOI: 10.1051/0004-6361/201220262, Vol.550, No.A94, pp.1-14, 2013
Abstract:

The question of the origin of magnetic fields of Ap/Bp stars is still regarded as an interesting puzzle of stellar astrophysics. We investigate the possibility that the randomness and relative complexity of these fields are remnants of a magnetic instability. In the studied scenario it is assumed a priori that the surface of an Ap star is slowed down in its early evolutionary stage more than its analogous A star. This leads to a significant differential rotation in its interior, making it possible to generate a strong toroidal magnetic field in the radiative zone. Under such circumstances the kink-type Tayler instability is likely to set in. The presented numerical simulations in a compressible, spherical domain show that the instability can produce large surface magnetic fields, even of the order of 0.01 − 1 of the internal toroidal component (depending on the setup). The resulting magnetic fields can then serve as “initial conditions” evolving into a stable magnetic configuration (however, the matter of long-term stability is not addressed here). This theory naturally supports the fact that Ap stars rotate typically slower than normal A stars (the Tayler instability is suppressed when rotation is too fast), it also qualitatively explains the dependence of the apparent obliquity of the main magnetic axis on the rotation period, as well as the existence of the minimum field threshold (no Ap stars have been observed with fields weaker than ≈ 102 G). Given that the generation of the initial differential rotation and initial poloidal fields are not discussed here, the results have a speculative nature and can be viewed as a possible step toward a full understanding of Ap star magnetism.

Keywords:

magnetic field, chemically peculiar, magnetohydrodynamics (MHD), instabilities

Affiliations:
Szklarski J.-IPPT PAN
Arlt R.-Leibniz-Institut für Astrophysik Potsdam (AIP) (DE)
8.Siemiątkowska B., Szklarski J., Gnatowski M., Mobile robot navigation with the use of semantic map constructed from 3D laser range scans, CONTROL AND CYBERNETICS, ISSN: 0324-8569, Vol.40, No.2, pp.437-453, 2011
Abstract:

We describe a system allowing a mobile robot equipped with a 3D laser range finder to navigate in the indoor and outdoor environment. A global map of the environment is constructed, and the particle filter algorithm is used in order to accurately determine the position of the robot. Based on data from the laser only, the robot is able to recognize certain classes of objects like a floor, a door, a washbasin, or a wastebasket, and places like corridors or rooms. For complex objects, the recognition process is based on the Haar feature identification. When an object is detected and identified, its position is associated with the appropriate place in the global map, making it possible to give orders to the robot with the use of semantic labels, e.g., “go to the nearest wastebasket”. The obstaclefree path is generated using a Cellular Neural Network, accounting for travel costs with distance or ground quality. This path planning method is fast and in comparison with the potential field method it does not suffer from the local minima problem. We present some results of experiments performed in a real indoor environment.

Keywords:

artificial intelligence, robotics, mapping

Affiliations:
Siemiątkowska B.-IPPT PAN
Szklarski J.-IPPT PAN
Gnatowski M.-IPPT PAN
9.Siemiątkowska B., Szklarski J., Gnatowski M., Borkowski A., Węclewski P., A mobile robot navigation with use of CUDA parallel architecture, JOURNAL OF AUTOMATION, MOBILE ROBOTICS AND INTELLIGENT SYSTEMS, ISSN: 1897-8649, Vol.5, No.3, pp.79-84, 2011
Abstract:

In this article we present a navigation system of a mobile robot based on parallel calculations. It is assumed that the robot is equipped with a 3D laser range scanner. The system is essentially based on a dual grid-object, where labels are attached to detected objects (such maps can be used in navigation based on semantic information). We use a classical SMPA (Sense - Model - Plan - Act) architecture for navigation, however, some steps concerning object detection, planning and localization are parallelized in order to speed up the entire process. The CUDA (Compute Unified Device Architecture) technology allows us to execute our algorithms on many processing units with use of a inexpensive graphics card which makes it possible to apply the proposed navigation system in a real time.

Keywords:

navigation, neural network, parallel computing

Affiliations:
Siemiątkowska B.-IPPT PAN
Szklarski J.-IPPT PAN
Gnatowski M.-IPPT PAN
Borkowski A.-IPPT PAN
Węclewski P.-other affiliation
10.Siemiątkowska B., Szklarski J., Syrczyński J., Węclewski P., Gnatowski M., Wykorzystanie filtrów cząstkowych w procesie lokalizacji robota mobilnego, POMIARY - AUTOMATYKA - ROBOTYKA. PAR, ISSN: 1427-9126, Vol.2, pp.344-353, 2011
Abstract:

W pracy omówiono metody określenia zmian położenia robota mobilnego w środowisku 3D. Przedstawiono dwie implementacje filtru cząsteczkowego, których celem jest przyspieszenie obliczeń. Omówiono metodę, w której zmiana położenia i orientacji odbywa się oddzielnie oraz metodę wykorzystującą procesory graficzne w algorytmie lokalizacji.

Keywords:

Filtry cząsteczkowe, lokalizacja, mapowanie 3D

Affiliations:
Siemiątkowska B.-IPPT PAN
Szklarski J.-IPPT PAN
Syrczyński J.-other affiliation
Węclewski P.-other affiliation
Gnatowski M.-IPPT PAN
11.Borkowski A., Siemiątkowska B., Szklarski J., Towards Semantic Navigation in Mobile Robotics, LECTURE NOTES IN COMPUTER SCIENCE, ISSN: 0302-9743, DOI: 10.1007/978-3-642-17322-6_30, Vol.5765, pp.719-748, 2010
Abstract:

Nowadays mobile robots find application in many areas of production, public transport, security and defense, exploration of space, etc. In order to make further progress in this domain of engineering, a significant barrier has to be broken: robots must be able to understand the meaning of surrounding world. Until now, mobile robots have only perceived geometrical features of the environment. Rapid progress in sensory devices (video cameras, laser range finders, microwave radars) and sufficient computational power available on-board makes it possible to develop robot controllers that possess certain knowledge about the area of application and which are able to reason at a semantic level.

The first part of the paper deals with mobile robots dedicated to operate inside buildings. A concept of the semantic navigation based upon hypergraphs is introduced. Then it is shown how semantic information, useful for mobile robots, can be extracted from the digital documentation of a building.

In the second part of the paper we report the latest results on extracting semantic features from the raw data supplied by laser scanners. The aim of this research is to develop a system that will enable a mobile robot to operate in a building with ability to recognise and identify objects of certain classes. Data processing techniques involved in this system include a 3D-model of the environment updated on-line, rule-based and feature-based classifiers of objects, a path planner utilizing cellular networks and other advanced tools. Experiments carried out under real-life conditions validate the proposed solutions.

Keywords:

semantic navigation, mobile robots, laser scanners

Affiliations:
Borkowski A.-IPPT PAN
Siemiątkowska B.-IPPT PAN
Szklarski J.-IPPT PAN
12.Szklarski J., Cellular Automata Model of Self-organizing Traffic Control in Urban Networks, BULLETIN OF THE POLISH ACADEMY OF SCIENCES: TECHNICAL SCIENCES, ISSN: 0239-7528, DOI: 10.2478/v10175-010-0041-3, Vol.58, No.3, pp.435-442, 2010
Abstract:

A model of city traffic based on NagelSchreckenberg cellular automaton (CA) model is presented. Traffic control is realized at intersections with two conflicting streams each (at any time at most one stream can have „green light” assigned to it). For simple and regular lattice-like networks which are considered, it is easy to find optimal switching periods giving maximum possible flow rates. These optimal strategies are compared with a self-controlling approach proposed by Lämmer and Helbing (2008), which has not been implemented in a CA model until now. Previous work proved that generally this method gives superior results when compared to classical methods. In this paper we show that for deterministic scenario such control leads to self-organization, and that the solution always quickly converges to the optimal solution which is known in this case. Moreover, we consider also non-deterministic case, in the sense that possibility of turning with given probability is allowed. It is shown that the self-controlling strategy always gives better results than any solution based on fixed cycles with green waves.

Keywords:

cellular automata model, self-organizing traffic control, urban networks

Affiliations:
Szklarski J.-IPPT PAN
13.Siemiątkowska B., Szklarski J., Gnatowski M., Zychewicz A., Budowa hybrydowej semantyczno-rastrowej reprezentacji otoczenia robota mobilnego na podstawie wskazań dalmierza laserowego 3D, POMIARY AUTOMATYKA KONTROLA, ISSN: 0032-4140, Vol.56, No.3, pp.279-282, 2010
Abstract:

W artykule przedstawiono metodę budowy hybrydowej rastrowo-obiektowej mapy otoczenia mobilnego na podstawie wskazań skanera laserowego 3D. Chmura punktów jest zapisywana w postaci zbioru wektorów normalnych. Składowe wektora są reprezentowane jako składowe RGB. Przeprowadzana jest segmentacja obrazu, a następnie dokonuje się klasyfikacji semantycznej. W procesie klasyfikacji wykorzystuje się cechy Haara oraz systemy regułowe. Każdy wykryty obiekt jest przypisywany do pewnej komórki mapy rastrowej. Mapa utworzona w ten sposób może być następnie wykorzystana w algorytmie nawigacyjnym – ułatwia współpracę robot-człowiek oraz planowanie trasy. Metoda jest kontynuacją algorytmu opisanego w artykule pt. ”Segmentacja danych otrzymanych z dalmierza laserowego 3D”.

Keywords:

nawigacja, reprezentacja środowiska

Affiliations:
Siemiątkowska B.-IPPT PAN
Szklarski J.-IPPT PAN
Gnatowski M.-IPPT PAN
Zychewicz A.-IPPT PAN
14.Siemiątkowska B., Szklarski J., Gnatowski M., Zychewicz A., Segmentacja danych otrzymanych z lasera 3D, POMIARY AUTOMATYKA KONTROLA, ISSN: 0032-4140, Vol.56, No.3, pp.275-278, 2010
Abstract:

Otoczenie robota – wnętrze budynku jak i obszar znajdujący się na zewnątrz może być podzielony na fragmenty, którym następnie możemy przypisać pewne znaczenie semantyczne. Przed przystąpieniem do dokonywania klasyfikacji należy jednak dokonać filtracji i segmentacji danych pomiarowych. W poniższym artykule przedstawione zostaną wyniki segmentacji chmury punktów, którą otrzymujemy na podstawie wskazań laserowego skanera 3D. Zastosowano nowatorską technikę, w której dane pomiarowe zamieniane są na postać kartezjańską, następnie obliczane są wektory normalne do powierzchni, na której punkty leżą. Składowe wektora są normalizowane i zapisywane w reprezentacji RGB. W wyniku opisanej transformacji powstaje kolorowy obraz. Dzięki temu problem segmentacji danych w przestrzeni 3D jest sprowadzony do zadania analizy kolorowych obrazów. Umożliwia to zastosowanie znanych z wizji algorytmów: usuwania szumów, rozrostu ziarna i segmentacji. Przeprowadzone eksperymenty w pomieszczeniu zamkniętym i na zewnątrz budynku potwierdziły efektywność przyjętej metody.

Keywords:

segmentacja, mapy 3D

Affiliations:
Siemiątkowska B.-IPPT PAN
Szklarski J.-IPPT PAN
Gnatowski M.-IPPT PAN
Zychewicz A.-IPPT PAN
15.Siemiątkowska B., Szklarski J., Gnatowski M., Borkowski A., System nawigacyjny wykorzystujący informację semantyczną, PRACE NAUKOWE POLITECHNIKI WARSZAWSKIEJ, SERIA: ELEKTRONIKA, ISSN: 0137-2343, Vol.2, No.175, pp.645-654, 2010
Abstract:

W poniższej pracy przedstawiono system nawigacyjny robota mobilnego. W procesie planowania trasy wykorzystuje się semantyczną wiedzę o otoczeniu. Robot wyposażony w skaner laserowy 3D analizuje otoczenie i przypisuje obserwowanym obiektom etykiety. Cel, do którego robot ma dotrzec jest wskazywany poprzez podanie nazwy obiektu. Możemy więc wydać polecenie typu jedź do ściany, do drzwi, czy też umywalki. Zastosowano hybrydową rastrowo-obiektową reprezentację otoczenia. W procesie planowania trasy zastosowano sieci komórkowe.

Keywords:

semantyczna nawigacja, roboty mobilne, sieci komórkowe

Affiliations:
Siemiątkowska B.-IPPT PAN
Szklarski J.-IPPT PAN
Gnatowski M.-IPPT PAN
Borkowski A.-IPPT PAN
16.Szklarski J., Gnatowski M., Siemiątkowska B., Borkowski A., System czasu rzeczywistego budowania mapy otoczenia pojazdu na podstwie danych z dalmierzy laserowych, PRACE NAUKOWE POLITECHNIKI WARSZAWSKIEJ, SERIA: ELEKTRONIKA, ISSN: 0137-2343, Vol.1, No.175, pp.665-674, 2010
Abstract:

W artykule przedstawiono system wspomagający pracę operatora zdalnie kontrolowanego pojazdu poprzez wizualizację najbliższego otoczenia jako mapy wysokośsci przeszkód. Informacje o otoczeniu zbierane są za pomocą dalmierzy laserowych 2D dokonujących pomiaru w jednej płaszczyźnie, dane dotyczące umiejscowienia i przechyłów pojazdu dostarczają inklinometr, radarowy czujnik prędkosci oraz moduł GPS. Na podstawie przemieszczania się pojazdu możliwa jest pełna rekonstrukcja środowiska, przy założeniu że jest ono całkowicie statyczne. Przedstawiono wyniki budowania mapy 2,5D dla trzech róznych środowisk: garażu podziemnego, przejazdu między budynkami i parkingu samochodowego.

Keywords:

mapa otoczenia, nawigacja, dalmierze laserowe

Affiliations:
Szklarski J.-IPPT PAN
Gnatowski M.-IPPT PAN
Siemiątkowska B.-IPPT PAN
Borkowski A.-IPPT PAN
17.Stefani F., Gerbeth G., Gundrum Th., Hollerbach R., Priede J., Rüdiger G., Szklarski J., Helical magnetorotational instability in a Taylor-Couette flow with strongly reduced Ekman pumping, PHYSICAL REVIEW E, ISSN: 1539-3755, DOI: 10.1103/PhysRevE.80.066303, Vol.80, pp.66303-66321, 2009
Abstract:

The magnetorotational instability (MRI) is thought to play a key role in the formation of stars and black holes by sustaining the turbulence in hydrodynamically stable Keplerian accretion disks. In previous experiments the MRI was observed in a liquid metal Taylor-Couette flow at moderate Reynolds numbers by applying a helical magnetic field. The observation of this helical MRI (HMRI) was interfered with a significant Ekman pumping driven by solid end caps that confined the instability only to a part of the Taylor-Couette cell. This paper describes the observation of the HMRI in an improved Taylor-Couette setup with the Ekman pumping significantly reduced by using split end caps. The HMRI, which now spreads over the whole height of the cell, appears much sharper and in better agreement with numerical predictions. By analyzing various parameter dependencies we conclude that the observed HMRI represents a self-sustained global instability rather than a noise-sustained convective one.

Keywords:

magnetohydrodynamics, magnetorotational instability, Taylor-Couette flow

Affiliations:
Stefani F.-Forschungszentrum Dresden-Rossendorf (DE)
Gerbeth G.-Forschungszentrum Dresden-Rossendorf (DE)
Gundrum Th.-Forschungszentrum Dresden-Rossendorf (DE)
Hollerbach R.-University of Leeds (UK)
Priede J.-Coventry University (UK)
Rüdiger G.-Astrophysikalisches Institut Potsdam (DE)
Szklarski J.-IPPT PAN
18.Stefani F., Gerbeth G., Gundrum Th., Szklarski J., Rüdiger G., Hellerbach R., Liquid metal experiments on the helical magnetorotational instability, Magnetohydrodynamics, ISSN: 0024-998X, Vol.45, No.2, pp.135-144, 2009
Abstract:

The magnetorotational instability (MRI) plays an essential role in the formation of stars and black holes. By destabilizing hydrodynamically stable Keplerian flows, the MRI triggers turbulence and enables outward transport of angular momentum in accretion discs. We present the results of a liquid metal Taylor–Couette experiment under the influence of helical magnetic fields that show typical features of MRI at Reynolds numbers of the order 1000 and Hartmann numbers of the order 10. Particular focus is laid on an improved experiment, in which split end caps are used to minimize the Ekman pumping.

Keywords:

magnetohydrodynamics, magnetorotational instability, Taylor–Couette experiment

Affiliations:
Stefani F.-Forschungszentrum Dresden-Rossendorf (DE)
Gerbeth G.-Forschungszentrum Dresden-Rossendorf (DE)
Gundrum Th.-Forschungszentrum Dresden-Rossendorf (DE)
Szklarski J.-IPPT PAN
Rüdiger G.-Astrophysikalisches Institut Potsdam (DE)
Hellerbach R.-University of Leeds (UK)

List of recent monographs
1.
53
Siemiątkowska B., Borkowski A., Chojecki R., Gnatowski M., Mokrzycki W., Szklarski J., Reprezentacja Otoczenia Robota Mobilnego , Akademicka Oficyna Wydawnicza EXIT, pp.1-263, 2011

Conference papers
1.Zawidzki M., Szklarski J., Single-branch Truss-Z Optimization Based on Image Processing and Evolution Strategy, PARENG2017, International Conference on Parallel, Distributed, Grid and Cloud Computing for Engineering, 2017-05-30/05-31, Pécs (HU), DOI: doi:10.4203/ccp.111.28, pp.28, 2017
Abstract:

Truss-Z (TZ) is a skeletal system for creating free-form pedestrian ramps and ramp networks among any number of terminals in space. TZ structures are composed of four variations of a single basic unit subjected to affine transformations (mirror reflection, rotation and combination of both). This paper presents a new approach to the optimization of the layout of a singlebranch Truss-Z (STZ) in constrained environment (E). The problem is formulated as follows: create an STZ from a start (sP) to end point (eP) without self-intersections and collisions with two obstacles. This is a multi-criterial optimization problem where three independent objectives are subjected to minimization: the total number of modules (n), the “reaching error” to eP and the “overlapping error”. All three criteria are weighted and aggregated to a single cost function (CF). The calculation of CF is based on image processing of rendered geometry of individual STZs in E. The optimization is performed by population-based classic heuristic method - Evolution Strategy (ES). The computation of CF is the most time consuming, however, its parallelization is rather straightforward. Two parallelization methods are presented: distribution over Wolfram Lightweight Grid and application of general purpose graphical processing units (GPGPUs) with the use of CUDA platform.

Keywords:

Extremely Modular System, Truss-Z, discrete optimization, image processing, rasterization, GPU, CUDA, Mathematica, Wolfram Lightweight Grid.

Affiliations:
Zawidzki M.-IPPT PAN
Szklarski J.-IPPT PAN
2.Zawidzki M., Szklarski J., Preliminary Optimization of Pipe-Z Reconfiguration, PARENG2017, International Conference on Parallel, Distributed, Grid and Cloud Computing for Engineering, 2017-05-30/05-31, Pécs (HU), DOI: doi:10.4203/ccp.111.27, pp.27, 2017
Abstract:

Pipe-Z (PZ) is a parametric design system which comprised of a congruent modules (PZM) allows the creation of complex three-dimensional, single-branch structures which can be represented by mathematical knots. Once the geometrical parameters are set for the PZM, the shape of PZ is controlled solely by relative twists of the PZMs in a sequence. Therefore each PZM has one degree of freedom (1DOF). This paper presents the preliminary optimization of PZ reconfiguration from a “straight tube” to a half-torus. Here the displacement of PZMs transverse to the “bending direction” is to be minimized. In other words, it resembles “truing” of a wheel. In the considered case, the PZ is comprised of eight hexagonal PZMs. Thus every PZM can have six possible positions relative to the previous module. The initial (PZI) and target (PZT) configurations are given. Since the time-steps and relative twists are discrete, it is a discrete optimization and has combinatorial nature. The number of possible configurations grows astronomically with the assumed number of time-steps from one position to another and the number of PZMs. However, the optimization algorithm can be naturally parallelized. At first the concept of PZ is outlined, followed by the experiment. The results are illustrated and discussed.

Keywords:

Extremely Modular System, Pipe-Z, Arm-Z, discrete optimization, dihedral rotation, “snakebot”, reconfiguration.

Affiliations:
Zawidzki M.-IPPT PAN
Szklarski J.-IPPT PAN
3.Zawidzki M., Jankowski Ł., Szklarski J., Structural optimization of a five-unit single-branch Truss-Z modular structure, SMART 2017, 8th Conference on Smart Structures and Materials, 2017-06-05/06-08, Madrid (ES), pp.525-535, 2017
Abstract:

Truss-Z (TZ) is an Extremely Modular System (EMS). Such systems allow for creation of structurally sound free-form structures, are comprised of as few types of modules as possible, and are not constrained by a regular tessellation of space. Their objective is to create spatial structures in given environments connecting given terminals without self-intersections and obstacle-intersections. In an EMS, the assembly, reconfiguration and deployment difficulty is moved towards the module, which is relatively complex and whose assembly is not intuitive. As a result, an EMS requires intensive computation for assembling its desired free-form geometrical configuration, while its advantage is the economization of construction and reconfiguration by extreme modularization and mass prefabrication. TZ is a skeletal modular system for creating free-form pedestrian ramps and ramp networks among any number of terminals in space. TZ structures are composed of four variations of a single basic module (Truss-Z module, TZM) subjected to affine transformations (mirror reflection and rotation). The previous research on TZ focused on global discrete optimization of the spatial configuration of modules. This contribution reports on the first attempts at structural optimization of the TZM for a single-branch TZ. Namely, the internal topology of a TZM and sizing of its elements are subject to optimization. An important challenge is due the fact that TZM is to be universal, i.e., it must be designed for the worst case scenario. There are four variations of each module, and due to symmetries there are thus 4^4 = 256 unique 5-unit configurations. The structural performance of all of them needs to be evaluated in terms of a typical structural criterion (the maximum von Mises effective stress), and used for structural optimization at the level of a single TZM.

Keywords:

Extremely Modular System, Truss-Z, Structural optimization, Effective stress

Affiliations:
Zawidzki M.-IPPT PAN
Jankowski Ł.-IPPT PAN
Szklarski J.-IPPT PAN
4.Białek Ł., Szklarski J., Borkowska M.M., Gnatowski M., Reasoning with Four-Valued Logic in Multi-robotic Search-and-Rescue Problem, AUTOMATION-2016, Challenges in Automation, Robotics and Measurement Techniques, 2016-03-02/03-04, Warszawa (PL), DOI: 10.1007/978-3-319-29357-8, Vol.440, pp.483-499, 2016
Abstract:

The aim of this paper is to present application of non-standard logic in the process of reasoning regarding the state of environment in a multi-robotic system. We have investigated the possibility that the usage of four-valued logic can serve as an alternative to the traditional probabilistic approach when handling the uncertainties. As a proof of concept, we have considered a typical search-and-rescue scenario in which a group of n robots performs a search for k victims localized in random positions in an initially unknown building. The building is represented in the form of a graph while the uncertainties are modeled by parameters denoting probabilities of victim observation and random blocking of a robot transition between neighboring nodes (which precludes the possibility for the robot to know anything about the actual graph structure with full confidence). The simulation results show that the unique features of applied reasoning language give significant improvement over typical approaches based on the two-valued logic. The results have a preliminary character, in the sense that up to now, only numerical experiments have been performed—applying the idea in a real multi-robotic system is currently underway.

Keywords:

Search-and-rescue problem, Reasoning engine, Four-valued logic, 4QL, Simulation

Affiliations:
Białek Ł.-University of Warsaw (PL)
Szklarski J.-IPPT PAN
Borkowska M.M.-IPPT PAN
Gnatowski M.-IPPT PAN
5.Gnatowski M., Siemiątkowska B., Szklarski J., Extraction of semantic information from 3D laser range Finder, IFToMM, 8th International Conference on Rotor Dynamics, 2010-09-12/09-15, Seoul (KR), pp.383-389, 2010
Abstract:

In this paper a system for extracting semantic information in indoor and outdoor environment from 3D laser scanner is presented. The largest objects (like walls, floor, ceiling, etc.) are recognized by constructing an RGB image based on normal vectors and applying a simple rule-based system. More sophisticated techniques are used to detect the remaining ones: Haar-like features – to classify small and irregular objects, and Cellular Neural Networks – to distinguish between different types of ground on which the robot is able to operate.

Keywords:

semantic information, laser range finder, navigation

Affiliations:
Gnatowski M.-IPPT PAN
Siemiątkowska B.-IPPT PAN
Szklarski J.-IPPT PAN
6.Szklarski J., AC08 System Description, ProMAS 2008, 6th International Workshop Programming Multi-Agent Systems, 2008-05-13/05-13, Estoril (PT), Vol.5442, pp.223-227, 2009