Domantas Bručas

Calibration of precision polygon/autocollimator measurement system

Measuring system of polygon/autocollimator is considered the most accurate widely available means of angle measurement, therefore its accuracy researches are of high importance. In this paper we describe the experiments of both autocollimators and polygon calibration implementing the equipment of average accuracy. The calibration data analysis given allows determining the errors of equipment without implementation of high accuracy reference means of measurement. The results of calibration of both autocollimators and precision polygon are also given in the paper.

Influence of digital camera errors on the photogrammetric image processing

Abstract The paper deals with the calibration of digital camera Canon EOS 350D, often used for the photogrammetric 3D digitalisation and measurements of industrial and construction site objects. During the calibration data on the optical and electronic parameters, influencing the distortion of images, such as correction of the principal point, focal length of the objective, radial symmetrical and non‐symmetrical distortions were obtained. The calibration was performed by means of the Tcc software implementing the polynomial of Chebichev and using a special test‐field with the marks, coordinates of which are precisely known. The main task of the research – to determine how parameters of the camera calibration influence the processing of images, i.e. the creation of geometric model, the results of triangulation calculations and stereo‐digitalisation. Two photogrammetric projects were created for this task. In first project the non‐corrected and in the second the corrected ones, considering the optical error...

Creation of a multi-reference-angle comparator

Many geodetic and industrial instruments utilize precise angle determination. Metrological calibration and testing of such devices is very complicated, due to the large number of angular position values generated, and often cannot be accomplished using classical means of angle determination. Therefore a special comparator (test rig) capable of calibration geodetic and other angle-measuring instruments and implementing multiple references for angle determination has been created. Several modernized optical devices were used on the test rig, together with the implementation of a special calibration method. In this paper the construction of the rig, modernization of the optical devices, calibration, and some results of measurements are presented.

Digital photogrammetry for building measurements and reverse‐engineering

Abstract Architectural photogrammetry is a technique to acquire three dimensional (volumetric) or two dimensional geometric data of buildings for a CAD model from their images. Usually photogrammetric methods (together with the laser scanning) are being implemented for the complex surfaces the measurement of which by any other means is extremely complicated. However, regular geometric forms can also be measured using this method. This is especially an issue in case of possible comparison of the results obtained by different means. In this paper the photogrammetric measurements of geometric elements of the building, with the comparison and evaluation of quality of the results are presented.

The correlation analysis of the angle measurements

Abstract The test bench for testing and calibrating the measuring geodetic instruments for flat angle measurements has been created at Vilnius Gediminas Technical University, Institute of Geodesy. This test rig incorporates multiple‐angular position determination principles ‐ photoelectric angular encoder, polygon‐autocollimator and circular‐scale‐microscope. Such a diversity of implemented methods allows cross‐calibration and testing each principle using the other one. Similarly, there may be multiple methods of testing and cross‐calibration used. The covariation and correlation analysis of the measurement data are received and analysed.

Development of a Novel Device for Attitude Control over Small Satellites

Recent years have faced a very modern trend for space exploration activities – constructing, launching and operating nanosatellites have become very popular. One of the major problems of implementing and taking control over the nanosatellite is ensuring accurate but simple and small dimension equipment for attitude control. Most of the equipment implemented for the introduced task was large and bulky in the past and could be hardly used on extremely small satellites. The paper describes equipment under development for attitude control over satellites. Equipment relies on the implementation of piezoelectric transducers for the rotation of a spherical body, i.e. reaction sphere, thus ensuring precise three-axis attitude control over the satellite by means of a single device. Further, the article focuses on the device under development with some calculations and examples of implementing such instruments.

Basic construction of the flat angle calibration test bench for geodetic instruments

In our days precise geodetic instruments are very widely used in geodesy, building structures, surveying, machine engineering etc. Many of those instruments are based on precise measurement of the directions differences (ie measurement of angles). Such instruments are: theodolites, digital theodolites, total stations etc. Testing and calibration of these instruments is quite complicated task, although it is evidently needed. In this paper we present the creation and preliminary research of accuracy of the test bench designed to perform the testing and calibration of such geodetic instruments.

ANALYSIS OF MEASUREMENT SYSTEM AS THE MECHATRONICS SYSTEM

The paper deals with the mechatronic arrangement for angle measuring system application. The objects to be measured are the circular raster scales, rotary encoders and coded scales. The task of the measuring system is to determine the bias of angle measuring standard as the circular scale and to use the results for the error correction and accuracy improvement of metal cutting machines, coordinate measuring machines, robots, etc. The technical solutions are given with the application of active materials for smart piezoactuators implemented into the several positions of angular measuring equipment. Mechatronic measuring system is analysed as complex integrated system and some of its elements can be used as separate units. All these functional elements are described and commented in the paper with the diagrams and graphs of errors and examples of microdisplacement devices using the mechatronic elements.

Research on presice point positioning and Real-Time Kinematics corrections for unmanned aerial vehicle global positioning systems

AbstractUnmanned Aerial Vehicles (UAVs) are used in different tasks with different flight path accuracy. To achieve a greater accuracy of flight trajectory GPS accuracy improvement methods are analyzed. The present article explains the main principles of GPS measurement. Precise Point Positioning (PPP) and Real-Time Kinematics (RTK) methods are described. and compared. Also, both methods have been tested.

Research of remotely piloted vehicles for cargo transportation

Remotely piloted vehicles (RPV) are used in various fields. The article analyses RPV usage for aerial cargo transportation. The first part is an overview of RPVs used across the world as cargo transportation, their examples and prototypes, as well as the comparison of their advantages and disadvantages. The second part is an analysis of aircraft structural components, by comparing their various configurations. The best cargo delivery method is analysed; and a mathematical model of cargo drop from vehicle is presented.