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PROBLEM OF IDENTIFICATION OF DETERMINISTIC CHAOS IN THE INTERACTIVE DRIVE SYSTEMS
Kratochvíl, Ctirad ; Švéda, P. ; Houfek, Martin ; Houfek, Lubomír
Chaos and chaos theory is a field of study in mathematics, computer sciences, electronics, physics and also engineering too. In our article will be explored chaotic behaviour and numerical solutions of the models of drive systems with electric DC motors. These solutions are also bounded like equilibrium, periodic and quasiperiodic solution. There is no precise definition for a chaotic solution because it cannot be represented through standard mathematical functions. However, a chaotic solution is aperiodic solution, which is endowed with some special identifiable characteristics, for example attractors, bifurcations or one-and two dimensional maps.
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Multipurpose experimental rig for aeroelastic tests of bridge girders and slender beams
Pospíšil, Stanislav ; Král, Radomil ; Náprstek, Jiří
The bridges, footbridges and broadcast towers create an important subset of infrastructure subjected to dynamic loading of various origins. Especially, exposed to wind, they are susceptible to vibrations under certain circumstances due to pure load action or aero-elastic effects. This means that once an element or a structure starts to vibrate, a complex interaction between the moving boundary and the airflow takes place. Because of the complexity, the research has been in progress for several decades in both theoretical and experimental way. The article describes an original and multi-purpose experimental frame for the analysis of complex linear and non-linear aspects of aero-elastic behavior of the slender beams. The apparatus meets the rigorous theoretical assumptions and allows very precise and quick adjustment of the stiffness and mass of the structure, which is not always possible with a traditional "parallel spring-supported bridge" approach used by many researchers.
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Dynamics of a vibration damperworking on a principle of a heavy ball rolling inside a spherical dish
Náprstek, Jiří ; Fischer, Cyril ; Pirner, Miroš
Wind excited vibrations of slender structures such as towers, masts or certain types of bridges can be reduced using passive or active vibration absorbers. If there is available only a limited vertical space to install such a device, a ball type of absorber can be recommended. In general, it is a semispherical horizontal dish in which a ball of a smaller diameter is rolling. Ratio of both diameters, mass of the rolling ball, quality of contact surfaces and other parameters should correspond with characteristics of the structure. The ball absorber is modeled as a holonomous system. Using Lagrange equations of the second type, governing non-linear differential system is carried out. The solution procedure combines analytical and numerical processes. As the main tool for dynamic stability investigation the 2nd Lyapunov method is used. The function and effectiveness of the absorber identical with those installed at the existing TV towers was examined in the laboratory.
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Concurrent mapping and localization based on potential fields
Věchet, Stanislav ; Krejsa, Jiří
Presented paper deals with Concurrent Mapping and Localization as a method to build the local map for the autonomous mobile robot. Building accurate local map is necessary for the successful navigation through the crowded environment densely populated with dynamic obstacles. The occupancy grid mapping algorithm was used due to the high uncertainty in the measurements of dynamic obstacles. As the occupancy grid algorithm is of probabilistic nature the implementation is straightforward and is also capable to generate the results in real-time.
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Mobile robot motion planner via neural network
Krejsa, Jiří ; Věchet, Stanislav
Motion planning is essential for mobile robot successful navigation. There are many algorithms for motion planning under various constraints. However, in some cases the human can still do a better job, therefore it would be advantageous to create a planner based on data gathered from the robot simulation when humans do the planning. The paper presents the method of using the neural network to transfer the previously gained knowledge into the machine learning based planner. In particular the neural network task is to mimic the planner based on finite state machine. The tests proved that neural network can successfully learn to navigate in constrained environment.
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Non-linear time heteronymous dymping in non-linear parametric planetary systems
Hortel, Milan ; Škuderová, Alena
The analysis of dynamics of time heteronymous weakly and strongly non-linear planetary transmission systems with kinematic coupling - gears constitutes a study of complicated function of many parameters including the gearing material damping properties and damping viscous properties of lubricating oil film in gear mesh. The structures with lightening holes in cogwheel discs are characterized by time variable damping in gear meshes. The following contribution deals with this time heteronymous non-linear damping.
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