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The theoretical and actual measurement accuracy of TRITOP photogrammetry system
Klus, Patrik ; Mendřický, Radomír (referee) ; Zatočilová, Aneta (advisor)
This diploma thesis examines the impact of selected factors on the measurement accuracy of Tritop photogrammetry system and verifies the validity of theoretical predictive formulas. Primary attention is given to factors that are easily influenced by the inspector - namely number of captured images, shooting distance, number of scale bars and number of coded targets. In addition, experiments dealing with the measurement automation and the use of external color filter are also described in this thesis. Seven scale bars placed on a jig of cube shape were subject of the measurements (according to VDI/VDE 2634 standard). Two approaches were used in order to obtain measurement deviations – reference values, from which the measured data were subtracted to obtain deviations, were known due to the use of scale bars. Second approach consisted in evaluation of deviations from software Tritop Professional. The results showed that the number of photographs and shooting distance have the greatest impact on measurement accuracy of Tritop system. The accuracy was also influenced by number of coded targets in the scene or by use of the external green filter. Measured data were compared to the values obtained from predictive formulas. The results showed that the formula defined by the GOM company has a prediction accuracy of more than 96 %. However the formula is dependent on the input parameter called “Image accuracy” for which the value recommendations are made in this work. The results of this work can help predict measurement uncertainties more precisely and optimize the measurement methodology of Tritop photogrammetry system.
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Optical measurement of deformations of flange joints
Schmidtová, Markéta ; Mendřický, Radomír (referee) ; Hurník, Jakub (advisor)
The diploma thesis addresses the topic of optical measurements of flange joints during tightening and thermal loading. Commercially available optical systems with decreasing invasiveness were compared in opportunity which offer to an industrial environment. Various conditions are evaluated in 3D (scanning, DIC) as well as in 2D (DIC). The data for evaluation of sensitivity and system accuracy together with the evaluation of the data range were obtained by the measurement. Data evaluation showed the same accuracy for 2D and 3D system and the possibility of quality inspection of the joint by assessing the inspection dimensions in operation.
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Application of very thin matte coatings
Hruboš, David ; Mendřický, Radomír (referee) ; Koutecký, Tomáš (advisor)
This diploma thesis deals with matte coatings for optical 3D scanning. The aim of this thesis is to find a method of spraying the mixture of TiO2 and ethanol that would provide layer thickness beyond the measurable range of the 3D scanner. A spray gun allowing deposition of atomized mixture was design. The coatings created by this gun and by airbrush gun, which is commonly used for this purpose, were compared. The matting effect, thickness and the influence of used TiO2 particles were investigated in the coatings. The paper shows method of applying coatings that ensure sufficient matting of the surface for scanning purposes, and simultaneously have thicknesses that should not affect scanning results.
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Research 3D scanner for scanning of problematic surfaces
Bátrla, Martin ; Mendřický, Radomír (referee) ; Koutecký, Tomáš (advisor)
This diploma thesis deals with design of 3D scanner for scanning problematic surfaces. The research part introduces the problem of 3D scanning and describes causes of random errors. Further, it contains a description and division of methods that leads to their elimination. The practical part of the thesis deals with design and description of hardware and software parts of the 3D scanner. The output of this work is device that is able to implement and compare quality of codification methods mainly for scanning of problematic surfaces. The functionality of equipment was verified by experimental measurement.
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Noncontact monitoring of dimensional accuracy of large-scale 3D printing
Paulíček, Jiří ; Mendřický, Radomír (referee) ; Koutecký, Tomáš (advisor)
This diploma thesis deals with a design and manufacture of a scanner that is used for online monitoring of a large-scale 3D printing of concrete mixtures. The aim is to design a scanner usable with an active print head designed at VUT. The scanner works on the principle of active laser triangulation, where a laser line is projected on an extruded material immediately behind the nozzle. The projection of the laser line on the extruded materiál is captured by a camera. During the design, FEM analysis was used due to the sizing of the main parts of the scanner depending on the deformations caused by the operating load. Excessive deformations would cause measurement inaccuracies. The height and width are calculated from the image in the MATLAB software. This manufactured scanner was tested during the printing of a real object.
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Forging measurement using passive stereo vision
Vítek, Petr ; Mendřický, Radomír (referee) ; Hurník, Jakub (advisor)
The measurement of forgings in the hot state allows for the adjustment of their dimensions and shape, which increases the efficiency of the production process, energy savings and less technological additions of material. A possible alternative to conventional approaches for measuring hot forgings is the application of passive stereovision, which is the focus of this paper. The objectives are to determine the accuracy of this approach with respect to conventional conditions, to highlight the scale structure for the detection of significant points and to select a method for surface detection and reconstruction. The proposed method allows surface reconstruction with an accuracy worse by one order of magnitude, compared to measurements under normal conditions. In a measurement volume of 0.3 m3, the standard deviation of points in the space of 0.28 mm was determined. A band-pass filter transmitting green light spectrum was chosen to represent the forging structure based on the study of spatial frequencies and experimental testing. The KAZE method achieved the highest number of detected feature points on the forging surface.
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Study of surface coating possibilities for 3D scanning purposes
Franke, Jakub ; Mendřický, Radomír (referee) ; Koutecký, Tomáš (advisor)
This diploma thesis deals with matte coatings for 3D scanning purposes. The coatings are made with spray gun which uses a vibrating membrane atomizer and air blow gun. A suspension of titanium dioxide and alcohol is used as a coating material. This thesis describes the effect of the spray gun process parameters on the deposited coatings. These include, for example type of the coating suspension or setup of the blow gun. Phase Doppler Anemometry was used to measure spray characteristics. Deposited coatings were measured with profilometer and scanned with 3D scanner to study their thickness and effect on the results of 3D reconstruction. The result of this work was the coating with thickness below 1 µm with good optical properties for 3D scanning purposes. Standard deviation of the captured point cloud from the reference plane was below 0.0011 mm.
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Research of the dynamics of the laser welding process
Horník, Petr ; Mendřický, Radomír (referee) ; Šebestová, Hana (referee) ; Mrňa,, Libor (advisor)
Laser welding is a modern welding method that has been widely adopted by the industry. With the increasing demands on weld quality, automated welding is being applied with advantage. There are requirements to implement welding process monitoring in accordance with the concept of Industry 4.0. This thesis develops methods for laser welding process monitoring. The resulting weld quality is largely influenced by the behaviour of the vapour-gas channel called the keyhole generated by the laser beam. However, direct observation of the keyhole during the welding process is difficult and indirect methods are often chosen, with an emphasis on non-contact optical methods. First, the observation of the plasma plume using a photodiode is verified, and then an innovative approach of detecting the back-reflected laser radiation using a camera is proposed. An optical extension for monitoring the welding process coaxially at the laser wavelength is assembled for this purpose. The aim of this thesis is to summarize the possibilities of detecting the welding process status and to propose a variant acceptable for industrial application. The image data obtained during the process represent the intensity distribution of the back-reflected laser radiation. Descriptive statistics and image segmentation methods are used to extract features from the intensity distribution. The distribution of back-reflected laser radiation is related to process parameters, keyhole geometry and some weld defects.
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Model of a matting spray for 3D scanning for coating thickness prediction
Koupil, Michael ; Mendřický, Radomír (referee) ; Koutecký, Tomáš (advisor)
This master's thesis deals with the design of a method for measuring dimensional parameters of layers applied by a spray gun, followed by the design of a computational model capable of calculating the ideal trajectory dimensions to achieve the most consistent layer thickness, which can predict this thickness at any point. Another goal is to verify the functionality and quality of the simulation of the computational model through a comparative experiment. A method for measuring the thickness of the applied matting layer was proposed. Dependences of the thickness of the applied layer on the movement speed of the spray gun and the nozzle distance from the misted surface were determined. A mathematical model was designed to calculate the deposition thickness at a specific point on the trajectory, allowing for application along general trajectories. A mathematical model for simulation of the application process was proposed. The computational model allows for the choice between automatic calculation of ideal parameters and manual adjustment of custom parameters.
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Forging measurement using passive stereo vision
Vítek, Petr ; Mendřický, Radomír (referee) ; Hurník, Jakub (advisor)
The measurement of forgings in the hot state allows for the adjustment of their dimensions and shape, which increases the efficiency of the production process, energy savings and less technological additions of material. A possible alternative to conventional approaches for measuring hot forgings is the application of passive stereovision, which is the focus of this paper. The objectives are to determine the accuracy of this approach with respect to conventional conditions, to highlight the scale structure for the detection of significant points and to select a method for surface detection and reconstruction. The proposed method allows surface reconstruction with an accuracy worse by one order of magnitude, compared to measurements under normal conditions. In a measurement volume of 0.3 m3, the standard deviation of points in the space of 0.28 mm was determined. A band-pass filter transmitting green light spectrum was chosen to represent the forging structure based on the study of spatial frequencies and experimental testing. The KAZE method achieved the highest number of detected feature points on the forging surface.
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