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Design of metasurfaces for advanced optical elements
Březina, Tomáš ; Kvapil, Michal (referee) ; Hrtoň, Martin (advisor)
Metasurfaces represent an intriguing class of materials with a wide range of promising applications, one of them being advanced planar optical elements for industrial production and imaging. The main goal of this thesis is to design such an optical element, namely a beam-shaper consisting of dielectric anostructures in HCTA (high constrast transmitarray) arrangement. The first part of this work introduces a simplified theoretical model of the optical response of building blocks that facilitates understanding of the basic functional mechanism behind the phase metasurfaces. To quantify the optical response of dielectric building blocks with enough precision, numerical FDTD simulations were employed. As a result, a database compatible with lithographic fabrication procedures was created. To find the phase distribution ensuring the desired beam-shaping function, two approaches were investigated and implemented: the semi-analytical method of geometric transformation and the iterative Gerchberg-Saxton algorithm. The final output of this work is then the distribution of building blocks within the metasurface that imprints into the impinging beam the previously calculated phase profile.
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Active Damping of Machine Tool Head
Škúci, Michal ; Marek, Jiří (referee) ; Březina, Tomáš (advisor)
The master’s thesis deals with building mechatronics model of machine tool head delivered by company TOSHULIN,a.s. for purpose of damping vibration. Mechanical part of the model is based on modeling of system of flexible bodies. Components are modeled in FEM program ANSYS and subsequently reduced using Craig-Bampton method. The system of flexible bo-dies is created in MBS program ADAMS. Model is linearized and subsequently reduced. As a element of active damping is used linearized model of magnetic bearing. For control is desig-ned PID controller. The comparison of damped and undamped model is conducted in the end.
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Active Compensation of Tool Deflection
Zarboch, Jaromír ; Marek, Jiří (referee) ; Březina, Tomáš (advisor)
This paper deals with design of tool deflection compensation system for milling spindle C1, provided by company TOSHULIN, a.s. A simplified simulation model of the spindle supplemented by compensatory elements was built by using programs ANSYS, MD ADAMS, Matlab/Simulink. As action elements there were use three piezoactuators each controled by PID controler. Efficiency of this compensation system was verified based on performed simulations.
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Using of Reinforcement Learning for Four Legged Robot Control
Ondroušek, Vít ; Maga,, Dušan (referee) ; Maňas, Pavel (referee) ; Singule, Vladislav (referee) ; Březina, Tomáš (advisor)
The Ph.D. thesis is focused on using the reinforcement learning for four legged robot control. The main aim is to create an adaptive control system of the walking robot, which will be able to plan the walking gait through Q-learning algorithm. This aim is achieved using the design of the complex three layered architecture, which is based on the DEDS paradigm. The small set of elementary reactive behaviors forms the basis of proposed solution. The set of composite control laws is designed using simultaneous activations of these behaviors. Both types of controllers are able to operate on the plain terrain as well as on the rugged one. The model of all possible behaviors, that can be achieved using activations of mentioned controllers, is designed using an appropriate discretization of the continuous state space. This model is used by the Q-learning algorithm for finding the optimal strategies of robot control. The capabilities of the control unit are shown on solving three complex tasks: rotation of the robot, walking of the robot in the straight line and the walking on the inclined plane. These tasks are solved using the spatial dynamic simulations of the four legged robot with three degrees of freedom on each leg. Resulting walking gaits are evaluated using the quantitative standardized indicators. The video files, which show acting of elementary and composite controllers as well as the resulting walking gaits of the robot, are integral part of this thesis.
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OPTIMIZATION OF A FUZZY CONTROL DESIGN WITH RESPECT TO A PARALLEL MECHANISM WORKSPACE
Andrš, Ondřej ; Maga, Dušan (referee) ; Singule, Vladislav (referee) ; Březina, Tomáš (advisor)
The Ph.D. thesis is focused on using the fuzzy logic for control of a parallel manipulator based on a Stewart platform. The proposed mechanism makes possible to simulate the physiological movements of the human body and observe degradation processes of the cord implants. Parallel manipulators such as a Stewart platform represent a completely parallel kinematic mechanism that has major differences from typical serial link robots. However, they have some drawbacks of relatively small workspace and difficult forward kinematic problems. Generally, forward kinematic of a parallel manipulators is very complicated and difficult to solve. This thesis presents a simple and efficient approach to design simulation model of forward kinematic based on Takagi-Sugeno type fuzzy inference system. The control system of the parallel manipulator id based on state-space and fuzzy logic controllers. The proposed fuzzy controller uses a Sugeno type fuzzy inference system (FIS) which is derived from discrete position state-space controller with an input integrator. The controller design method is based on anfis (adaptive neuro-fuzzy inference system) training routine. It utilizes a combination of the least-squares method and the backpropagation gradient descent method for training FIS membership function parameters to emulate a given training data set. The proposed fuzzy logic controllers are used for the control of a linear actuator. The capabilities of the designed control system are shown on verification experiment.
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Application of Voronoi Diagrams in Robot Motion Planning
Pich, Václav ; Březina, Tomáš (referee) ; Šeda, Miloš (advisor)
This diploma project is focused on possible applications of computational geometry methods for robot motion planning among static and dynamic obstacles, particularly based on global robot motion planning by means of generalised Voronoi diagrams. The main effort was to convert this complex geometric and analytic problem to graph theory environment where the tasks of planning and searching paths between pairs of the graph vertices are effeciently solvable. The Voronoi diagram is created considering the whole searching space, while edges of this diagram satisfy that the distance from the surrounding obstacles is maximised and the path found along the Voronoi diagram edges is optimised from the point of view of its security (and it is collision-free).
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Pressure and Flow Rate Regulation Design for Pump-Tank System
Kovář, Jiří ; Němec, Zdeněk (referee) ; Svoboda,, Miroslav (referee) ; Březina, Tomáš (advisor)
The proposed work is dealing with control design of pump-tank system as part of broader water-supply network with using of mechatronic approach. The main goal of this work is design of control for regulation of flow, pressure and water level in tank in water-supply network of Vsetin city. This water-supply network consists of various components, such as pumps, pipes, valves, tanks etc. For the purpose of the control design is necessary to create a model of pipe network. The solution of hydraulic analysis is obtained by using the gradient method, which was implemented into the software solution named ADAM. The results of hydraulic analysis are compared with measured values of flow and pressure and difference of these values has to be minimalized by proposed calibration and verification process. The calibration and verification process was implemented in software ADAM. The essence of design control is formulating control problem as optimization problem. Therefore the output of higher control layer is set of procedural rules, which determines for example speed of pumps in time etc. Results were verified by using for this purpose developed computational server (ADAM Server).
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Controller design with using CARLA method
Jasanský, Michal ; Houška, Pavel (referee) ; Březina, Tomáš (advisor)
This bachelor thesis is focused on the application repeatedly reinforcement learning method named „Continuous Action Reinforcement Learning Automata“ (CARLA). There is recapitulated a basic describe of the artificial intelligence method, however it deals mainly with the CARLA method. In the thesis are described the advantages, disadvantages and the type of mathematical basis for simplified version of the CARLA method. The main part of the thesis is concerned with the method testing and debugging. The influence of the setting the parameters is also demonstrated in the thesis. The method is successfully applied on two systems: DC motor and physical pendulum.
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Simulation Assessment of X Axis Damping Possibilities of Heavy Machine Tool
Štetina, Jakub ; Marek, Jiří (referee) ; Březina, Tomáš (advisor)
This master's thesis deals with the simulation assessment of axis X damping possibilities of Heavy Machine Tools. CAD model has been provided by company TOSHULIN a.s. In the thesis, there is described modelling of axis X as multi body system consisting of rigid and flexible bodies. The main goal is to create simplified model and get the information for strategic decision of manufacturer about damping possibilities of axis X. For the solution has been used several software products: SolidWorks 2013 - for simplifying the CAD models, Ansys 14.5. for modelling od flexible bodies, MSC.Adams for modelling multi body systems and Matlab 2012 for data processing and optimization.
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