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1

Supervisory fault tolerant control of the GTM UAV using LPV methods

Péni T., Vanek B., Szabó Z., Bokor J.

International Journal of Applied Mathematics and Computer Science

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2015

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Vol. 25, no. 1

117--131

EN

A multi-level reconfiguration framework is proposed for fault tolerant control of over-actuated aerial vehicles, where the levels indicate how much authority is given to the reconfiguration task. On the lowest, first level the fault is accommodated by modifying only the actuator/sensor configuration, so the fault remains hidden from the baseline controller. A dynamic reallocation scheme is applied on this level. The allocation mechanism exploits the actuator/sensor redundancy available on the aircraft. When the fault cannot be managed at the actuator/sensor level, the reconfiguration process has access to the baseline controller. Based on the LPV control framework, this is done by introducing fault-specific scheduling parameters. The baseline controller is designed to provide an acceptable performance level along all fault scenarios coded in these scheduling variables. The decision on which reconfiguration level has to be initiated in response to a fault is determined by a supervisor unit. The method is demonstrated on a full six-degrees-of-freedom nonlinear simulation model of the GTM UAV.

2

Isotropy analysis of metamaterials

Kalvach A., Szabó Z.

Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska

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2015

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nr 4

52--54

EN

Metamaterials – artificial periodic structures with subwavelength feature sizes – can be characterized with macroscopic electromagnetic properties, like refractive index and wave impedance, just like homogeneous materials. However, in contrast to homogeneous materials, their properties depend strongly on the angle of incidence. 3D metamaterial structures can exhibit homogeneous behaviour, but their fabrication is challenging compared to layered (2D) metamaterials. Here we demonstrate with an example, that layered (2D) metamaterials can also exhibit homogeneous behaviour despite of their anisotropic geometry.

PL

Metamateriały – sztuczne struktury periodyczne o wymiarze charakterystycznym porównywalnym z długością fali – można scharakteryzować za pomocą tych samych właściwości jak dla materiałów homogenicznych np. współczynnikiem załamania czy impedancją falową. Jednakże, w przeciwieństwie do materiałów homogenicznych, ic parametry silnie zależą od kąta padania fali. Trójwymiarowe struktury metamateriałów mogą wykazywać jednorodne zachowanie, ale ich wykonanie jest trudne w porównaniu do metamateriałów warstwowych (2D). W artykule pokazujemy na przykładzie, że metamateriały warstwowe (2D) mogą również wykazywać jednorodne zachowanie pomimo ich anizotropowej geometrii.

3

LPV design of fault-tolerant control for road vehicles

Gáspár P., Szabó Z., Bokor J.

International Journal of Applied Mathematics and Computer Science

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2012

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Vol. 22, no. 1

173-182

EN

The aim of the paper is to present a supervisory decentralized architecture for the design and development of reconfigurable and fault-tolerant control systems in road vehicles. The performance specifications are guaranteed by local controllers, while the coordination of these components is provided by a supervisor. Since the monitoring components and FDI filters provide the supervisor with information about the various vehicle maneuvers and the different fault operations, it is able to make decisions about necessary interventions into the vehicle motions and guarantee reconfigurable and fault-tolerant operation of the vehicle. The design of the proposed reconfigurable and fault-tolerant control is based on an LPV method that uses monitored scheduling variables during the operation of the vehicle.

4

Relation between gravity time variation, vertical surface movements and sediment thickness in the Carpathian Basin

Völgyesi L., Csapó G., Szabó Z.

Reports on Geodesy

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2005

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z. 2/73

255-262

EN

The investigation of phenomena, influencing the short time variation of gravity, has gained importance with the increasing accuracy of gravity meters. Accordingly, we have studied vertical surface movements, attributable to two effects: compaction of sediments, on the one hand, and structural movements, on the other in the young sedimentary Pannonian Basin. ln most of the deep sedimentary regions positive correlation can be found between sediment thickness and subsidence. As a consequence of subsidence, observation pointsof the surface get into a different equipotential level of the Earth's gravity field. Calculating the effects of the vertical surface movements, determined by repeat levelling, for a 10-year time span, the variation of gravity io general should be about 3 μGal (1 μGal = 10-8m/s2), but at special places it may reach as much as 10-20 μGal.

5

Changes of gravity influenced by water-level fluctuations based on measurements and model computations

Csapó G., Szabó Z., Völgyesi L.

Reports on Geodesy

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2003

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z. 1/64

143-153

EN

More than 70% of the Earth's surface is covered by water. The outward form of this enormous volume of water is extremely variable. The majority is represented by oceans, seas and riversbut the quantity represented by subterranean water, arctic ice and precipitation (rain, snow) as well as that accumulated by human activity in reservoirs is not neglectable either. The influence of these volumes of water on the gravity field can be grouped in several ways: according to areal extension (global, regional, local), according to the causes producing the effects (tide, geodynamical processes, human activity), or according to the temporal variation of the causes (periodic, secular). In our paper we are presenting the results of our gravity measurements investigating the influence of local water-table variations, the daily variation of the quantity of water in an 80000 m3 urban reservoir, and the water-leveI fluctuations of the Danube. For the field work two LCR-G gravimeters were used, engineering geophysical soundings were carried out (using a penetrometer), and the available water-Ievel observations of the region were analyzed. For modeling we have computed the gravity effects either by supposing a Bouguer plate or by decomposing the irregular body into a series of regular bodies. The effect of water masses on the topographic correction was also modeled. The results can be useful in selecting localitiesfor stations of a gravity base network or for studying secular variations of the gravity field by repeated measurements.

6

Parametric excitation of pipes through fluid flow

Szabó Z.

Computer Assisted Mechanics and Engineering Sciences

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1999

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Vol. 6, No. 3-4

487-494

EN

In this paper the dynamic behaviour of a continuum inextensible pipe containing fluid flow is investigated. The fluid is considered to be incompressible, frictionless and its velocity relative to the pipe has the same but time-periodic magnitude along the pipe at a certain time instant. The equations of motion are derived via Lagrangian equations and Hamilton's principle. The system is non-conservative, and the amount of energy carried in and out by the flow appears in the model. It is well-known, that intricate stability problems arise when the flow pulsates and the corresponding mathematical model, a system of ordinary or partial differential equations, becomes time-periodic. The method which constructs the state transition matrix used in Floquet theory in terms of Chebyshev polynomials is especially effective for stability analysis of systems with multi-degree-of-freedom. The stability charts are created w.r.t. the forcing frequency omega, the perturbation amplitude nu and the average flow velocity U.