Model vrtulové pohonné jednotky s variabilním úhlem náběhu

The contribution deals with the mathematical model of the propeller drive unit with variable pitch. The introductory part of the article aims at a general mathematical description of the internal structure of the aircraft propulsion. The DC motor and propeller model are presented in next chapter. The last part presents the comparison between MatLab Simulink model and experimental laboratory stand of variable pitch drive unit. Variable pitch propeller drive is useful to minimize power consumption. The use of these units for the drones is only experimental in terms of optimization of energy consumption.V tomto článku je popsán matematický model vrtulové pohonné jednotky s variabilním úhlem náběhu vrtulových listů (VPPU). V úvodní části článku je popsán základní matematický model celé pohonné jednotky. V další části je popsán model motoru ve vazbě s vrtulí. V závěru článku je prezentován výstup simulací v MatLab Simulink v porovnání s výstupy s laboratorního standu. Význam VPPU je v možné úspoře energie letounu. Využití těchto jednotek pro pohon dronů za účelem snižování spotřeby energie je v současnosti jen na experimentální úrovni

Prediktivní řízení teploty přehřáté páry

This contribution deals with design and implementation of control system for superheated steam temperature, which is most often carried out by injection of the feed water. In the proposed control system, a common cascade control system is replaced by a predictive controller. This can quickly respond to rapid and unpredictable changes in steam consumption. The accuracy of the predictive controller design has been verified not only by digital simulation but directly in real process. The quality of the newly designed controller was compared to the originally implemented cascade control.Článek se zabývá návrhem a realizací regulačního obvodu pro řízení teploty přehřáté páry, která je dnes nejčastěji prováděna vstřikem napájecí vody. V navrženém regulačním obvodu je běžný rozvětvený regulační obvod s pomocnou regulovanou veličinou nahrazen prediktivním regulátorem. Tím lze rychle reagovat na rychlé a nepředvídatelné změny ve spotřebě páry. Správnost návrhu prediktivního regulátoru byla ověřena nejen pomocí číslicové simulace, ale přímo v běžném provozu. Kvalita řízení nově navrženého regulátoru byla porovnána s původně implementovaným kaskádovým řízením

Klouzavé řízení a jeho modifikace

The paper describes design of sliding mode control. The advantage of this control algorithm is a high robustness, simplicity, and the fact that it does not need knowledge of a mathematical model, only the control system’s order and the ability to measure control disturbances. The disadvantage is a high control activity, which is not useful for all types of control elements. Further there is description of the primary approach to sliding control design, which consists in the extension of nonlinear sliding control of an integration element. For the stabilization task this algorithm will significantly lower the activity of a control variable while maintaining its robustness. In case of following the state trajectory the activity of a control variable will also lower, if the change in the required trajectory is not to fast.Příspěvek popisuje návrh klouzavého řízení. Výhodou tohoto algoritmu řízení je jednoduchost a robustnost, není nutná přesná znalost matematického modelu, pouze musíme znát řád řízeného podsystému a regulační odchylky musí být měřitelné. Nevýhodou jsou rychlé změny akční veličiny. Dále je zde uveden původní přístup k návrhu klouzavého řízení rozšířením o integrační složku. V případě stabilizace se výrazně sníží aktivita akční veličiny oproti nespojitému klouzavému řízení. Pokud změny požadované trajektorie nejsou rychlé, výrazně se sníží aktivita řízení i pro úlohu sledování stavové trajektorie

Laser beam calibration for wood surface colour treatment

Laser engraving of photographs on wood surfaces is a challenging task. To optimize the outcome and production quality it is necessary to control every aspect of the laser engraving process. Most of the production machines and technologies overall are mainly focused on laser power control. However, with other systems and deeper knowledge of the wood characteristics it is possible to achieve even better quality. This paper deals with enlarging the number of achievable shades of burned wood and its optimization. A calibration system was developed to control colour shades of engraved wood with a combination of laser power and optic focus. With this approach it is possible to widen achievable palette of engraved shades by continuous control of chemical processes of laser and wood interaction. The production is divided into wood burning and wood carbonization by variation of laser beam focus.Web of Scienc

Actively controlled journal bearing enabling to expand limits of stability

The lecture deals with the stability of the movement of the journal inside the hydrodynamic plain bearings, which limits the operating rotational speed. The purpose of active vibration control using piezoactuators is to increase the limit of the rotor stable rotation speed and control the journal position. Besides theory it will be presented the results of testing the first prototype of this type of the bearings

The learning path to neural network industrial application in distributed environments

Industrial companies focus on efficiency and cost reduction, which is very closely related to production process safety and secured environments enabling production with reduced risks and minimized cost on machines maintenance. Legacy systems are being replaced with new systems built into distributed production environments and equipped with machine learning algorithms that help to make this change more effective and efficient. A distributed control system consists of several subsystems distributed across areas and sites requiring application interfaces built across a control network. Data acquisition and data processing are challenging processes. This contribution aims to present an approach for the data collection based on features standardized in industry and for data classification processed with an applied machine learning algorithm for distinguishing exceptions in a dataset. Files with classified exceptions can be used to train prediction models to make forecasts in a large amount of data.Web of Science912art. no. 224

Actively Controlled Journal Bearings for Machine Tools

The advantage of journal hydrodynamic bearings is high radial load capacity and operation at high speeds. The disadvantage is the excitation of vibrations, called an oil whirl, after crossing a certain threshold of the rotational speed which depends on the radial bearing clearance, the viscosity of lubricating oil, and the rotor mass. A passive way of how to suppress vibrations consists of adjusting the shape of the bearing bushing. Vibrations can be suppressed using the system of active vibration damping with piezoactuators to move the bearing bushing in two directions. The displacement of the bearing bushing is actuated by two piezoactuators, which respond to the position of the bearing journal relative to the bearing housing. Two stacked linear piezoactuators are used to actuate the location of the bearing bushing. A pair of capacitive sensors senses the position of the journal or shaft. The system of the actively controlled journal bearings is the first functional prototype in the known up to now. It works with a cylindrical bushing which does not require special technology of manufacturing and assembly. This new bearing enables not only to damp vibrations but also serves to maintain the desired bearing journal position with an accuracy of micrometers

A method for measuring the quality of graphic transfer to materials with variable dimensions (wood)

The transfer of graphics to a product's surface is a widely known technology. Printing, engraving, and etching are used every day in production processes with countless types of materials. This paper deals with quality control for laser engraving on surfaces with variable dimensions via optical sensors. The engraving process, apart from colour changes, can induce volume and moisture changes, which lead to dimension changes in some materials. Natural materials and biomaterials are among the ones most affected. Combined with the porous and inhomogeneous structure of such a material, it can be difficult to measure the quality of graphic transfer, especially for shaded products. The quality control of laser-engraved photographs on thin layers of wood veneer was selected as a suitable problem to solve. A complex method for the quality measurement of the specified production was designed and tested. We used an affine transformation to determine the system behaviour and to determine the transfer function of material changes during the production process. Moreover, there is a possibility to compensate the image deformation of the engraved product.Web of Science2216art. no. 603

Machine vision-based fatigue crack propagation system

This paper introduces a machine vision-based system promising low-cost solution for detecting a fatigue crack propagation caused by alternating mechanical stresses. The fatigue crack in technical components usually starts on surfaces at stress concentration points. The presented system was designed to substitute a strain gauge sensor-based measurement using an industrial camera in cooperation with branding software. This paper presents implementation of a machine vision system and algorithm outputs taking on fatigue crack propagation samples.Web of Science2218art. no. 685

Možnosti řízení tepelných systémů

This contribution describes different approaches to thermal system control. Not only PID control but also sliding mode controls were used. In addition the different modifications of sliding mode control were used, such as extension with integral element or continuous substitution of sign function. Considering the thermal system allows applying cooling element, the control algorithm using cooling and heating parts was tested too. All designed algorithms were verified with help of computer simulation and also directly on laboratory stand. All used control algorithms ensured required temperature but with different control quality.Příspěvek popisuje různé přístupy k řízení tepelných systémů. Kromě klasické PID regulace byly použity algoritmy řízení pracující v klouzavém režimu. Také byly použity další modifikace klouzavého řízení a to jak rozšíření o integrační složku, tak i spojitá náhrada znaménkové funkce. Vzhledem k tomu, že použitý tepelný systémy může používat i chlazení, bylo vyzkoušeno i řízení kombinující jak zahřívání, tak i chlazení. Všechny navržené algoritmy řízení byly ověřeny pomocí číslicové simulace i přímo na laboratorním zařízení. Všechny použité algoritmy dosáhly žádané teploty, avšak s rozdílnou kvalitou řízení