Norbert Tarcai

Eötvös Loránd University, Budapest, Budapest fovaros, Hungary

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Publications (3)4.28 Total impact

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    ABSTRACT: We present the first decentralized multi-copter flock that is capable of stable autonomous outdoor flight. By autonomous we mean that all members navigate themselves based on the dynamic information received from other robots in the vicinity, without any central data processing or control. Instead, all the necessary computations are carried out by miniature on-board computers. The only global information the system exploits is from GPS receivers, while the units use wireless modules to share this positional information with other flock members locally. Collective behavior is based on a decentralized control framework with bio-inspiration from statistical physical modelling of animal swarms. The model allows for stable group flight even in noisy, windy, delayed and error-prone environment. Using this framework we successfully demonstrated several fundamental collective flight tasks with up to 11 units: i) we achieved self-propelled flocking in a bounded area with self-organized object avoidance capabilities and ii) performed collective target tracking with stable formation flights (grid, rotating ring, straight line). With realistic numerical simulations we demonstrated that the local broadcast-type communication and the decentralized autonomous control method allows for the scalability of the model for larger flock sizes.
    02/2014;
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    ABSTRACT: Animal swarms displaying a variety of typical flocking patterns would not exist without underlying safe, optimal and stable dynamics of the individuals. These patterns can be efficiently reconstructed with simple flocking models, based on three simple rules: cohesion of the flock, repulsion of neighbouring individuals and alignment of velocity between neighbours. When designing robot swarms, the controlling dynamics of the robots can be based on these models. In this paper we present such a flocking algorithm endowing flying robots with the capability of self-organized collective manoeuvring. The main new feature of our approach is that we include a term in the velocity alignment part of the equations which is an analogue of the usual frictional force between point-wise bodies. We also introduce a generalized mathematical model of an autonomous flying robot, based on flight field tests. With simulations, we test the flocking algorithm from the aspects of the most general deficiencies of robotic systems, such as time delay, locality of the communication and inaccuracy of the sensors. Some of these deficiencies often cause instabilities and oscillations in the system. We show that the instabilities can be efficiently reduced in all states of the system by the inclusion of the friction-like velocity alignment, resulting in stable flocking flight of the robots.
    Bioinspiration &amp Biomimetics 10/2013; 9(2). · 2.41 Impact Factor
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    ABSTRACT: We have developed an experimental setup of very simple self-propelled robots to observe collective motion emerging as a result of inelastic collisions only. A circular pool and commercial RC boats were the basis of our first setup, where we demonstrated that jamming, clustering, disordered and ordered motion are all present in such a simple experiment and showed that the noise level has a fundamental role in the generation of collective dynamics. Critical noise ranges and the transition characteristics between the different collective patterns were also examined. In our second experiment we used a real-time tracking system and a few steerable model boats to introduce intelligent leaders into the flock. We demonstrated that even a very small portion of guiding members can determine group direction and enhance ordering through inelastic collisions. We also showed that noise can facilitate and speed up ordering with leaders. Our work was extended with an agent-based simulation model, too, and close similarity between real and simulation results was observed. The simulation results show clear statistical evidence of three states and negative correlation between density and ordered motion due to the onset of jamming. Our experiments confirm the different theoretical studies and simulation results in the literature on the subject of collision-based, noise-dependent and leader-driven self-propelled particle systems.
    Journal of Statistical Mechanics Theory and Experiment 04/2011; 2011(04):P04010. · 1.87 Impact Factor