Accuracy Of Coordinate Determination Research Articles

METHOD OF ULTRASONIC PHASE TWO-COORDINATE INFORMATION REGISTRATION FOR AUTOMATED NON-DESTRUCTIVE TESTING SYSTEMS

The article is devoted to the issue of improving the coordinate registration of information in means of automated non-destructive testing. Existing systems of non-contact registration of spatial position sensors of non-destructive testing are mostly focused on the use of signal fields of different physical nature, for example, acoustic or optical, which are created around the position of these sensors and amplitude methods of signal processing. These methods do not provide the necessary accuracy of determining the coordinates in the case of using small-aperture sensors of non-destructive testing.
 The basis of the proposed technical solution is the trilateration method. The distance between the emitter of ultrasonic vibration, which is structurally connected to the sensor, and the two receivers is determined by the phase method. This method provides increased accuracy in determining the coordinates of the sensor. Eliminating the ambiguity of phase measurements is based on the combination of the multi-frequency method and the numerical system of residual classes. This makes it possible to minimize the probability of incorrect resolution of the ambiguity of the results of phase distance measurements and to ensure high accuracy of coordinate determination (with an absolute error of the order of mm). The idea of the method and the main calculation formulas that make it possible to determine the modules of the numerical system of residual classes and the values of the operating frequencies of ultrasonic oscillations are presented. Matching the discretes for determining the phase shifts of signals with the modules of the numerical system of residual classes at different operating frequencies makes it possible to reduce the resolution of the ambiguity of the results of phase measurements to the task of restoring integers in the positional counting system from their representation by residuals in the numerical system of residual classes. The mechanism of occurrence of gross errors in the recovery of whole numbers is considered. An algorithm for eliminating this error is proposed. In general, the correctness of the algorithm for determining the sensor coordinates is confirmed by the simulation results. The considered method of two-coordinate information registration can be used both in the development of new automated means of non-destructive testing, and for the improvement of existing ones, which involve a manual method of scanning the surface of testing objects.

On the problem of increasing accuracy of coordinates determination of a machine-tractor unit by information and navigation equipment of a parallel driving system

BACKGROUND: The Federal Scientific and Technical Program for the Development of Agriculture on 20172025 deals with the creation and implementation of competitive domestic technologies based on the scientific achievements. Therefore, the development and investigation of parallel driving systems for a machine-tractor unit with information and navigation equipment in the direction of increasing their accuracy of coordinates determination are relevant.
 AIMS: Improving the accuracy of coordinates determination of the software and hardware complex for the parallel driving system based on algorithms for correcting and filtering information data of navigation equipment.
 METHODS: The simulation of the machine-tractor unit (MTU) is carried out in MATLAB/Simulink and contains the models of physical modules of coordinates correction for cases of tilt, geographic coordinates transformation into plane coordinates, orientation and velocity of the machine-tractor unit and the Kalman filter.
 RESULTS: Using the proposed mathematical model, a simulation of a machine-tractor unit operation with a parallel driving system is carried out. The adequacy of theoretical studies is confirmed by large-scale bench and field tests. The scientific novelty of the study lies in the proposed algorithms for correction of datas obtained from GPS/GLONASS receivers (computer program registration certificate No. 2019617131), the implementation of the 3D visualization of the machine unit on a tablet screen with the Android operating system (computer program registration certificate Nos. 2018613106 and 2020613458).
 CONCLUSIONS: The practical meaning of the present study lies in usability of the proposed algorithms for corrections and filtration of navigation equipment data under creating modern hardware and software systems for parallel driving of a machine-tractor unit.

ГЕОДЕЗІЯ, КАРТОГРАФІЯ І АЕРОФОТОЗНІМАННЯ

The aim. The study of formulas determination of the point coordinates by the inverse linear-angular intersection method. Previously, we investigated the possibility of using electronic total stations to control the geometric parameters of industrial buildings. The applied application of electronic total stations for high-precision measurements has been investigated as well. [Vivat, 2018]. The formula for optimal use of the device with certain accuracy characteristics relative to the measured basis is analytically proved and derived [Litynskyi, 2014]. Measurements on the basis of the II category are performed and theoretical calculations are confirmed. The possibility of achieving high accuracy in determining the segment by the method of linear-angular measurements is shown [Litynsky, 2015]. The influence of the angle value on the accuracy of determining the coordinates by the sine theorem is investigated and the possibility of optimizing the determination of coordinates by the method of inverse linear-angular serif by the formulas of cosines and sines is investigated [Litynskyi, 2019]. Method. Establishing a mathematical interconnection between measured values (distances and angles) with the required (flat coordinates of a point), differentiation and finding the minima of functions. Results.There were five formulas selected, of which six combinations had been created to calculate the increments of coordinates and to estimate their accuracy. Numerical experiments show that neither method has a significant advantage, which is supported by the results presented in the graphs and tables. It is worth noting one feature of the second method - in which it is possible to determine the increments of coordinates with an accuracy that exceeds the accuracy of measuring the sides. The possibility of optimizing the coordinate increments determination due to the choice of calculation formulas is considered. The possibility of increasing the accuracy of determination of the coordinates increments using different calculation formulas is researched. Consequently, it is suggested to optimize the choice of calculation formulas depending on the position of the desired point. The results of these studies can be used to create electronic total station or laser tracker application software in order to improve the accuracy of coordinate determination.

Результати застосування програмного забезпечення для визначення елементів зовнішнього орієнтування цифрових зображень аеротопографічного знімання з БПЛА

One of the problems with the use of UAVs for high-precision mapping is the inability to install on these devices an accurate stabilization system to determine the angular EEO images, so there is a need to develop methods for accurate location of EEO. To date, there are many developments in the definition of elements of EEO. However, there are a number of issues in their practical implementation. This applies primarily to attempts to improve the accuracy of obtaining the coordinates of the points of objects on the ground. Aim. Investigate the possibility of the proposed algorithm for determining the elements of EEO of digital images obtained by aerial surveying from an UAV. Methodology. Based on the condition of collinearity, two types of functions are determined for which the minimum is searched. This process of determining the elements of the EEO is performed using software. A diverse set of programs makes it possible to implement such a search, and a reasonable initial approximation of the EEA and provides a definition of their optimal parameters [Hlotov, 2020; Zavarzin, 2013; Berezina, 2018; Kim Hon Ir, 2017]. Results. The proposed approach was tested on the corresponding digital images obtained by aerial surveying from UAVs at checkpoints, which made it possible to justify the effectiveness of the proposed method. The specified RMSE had the following values: = 0.15 m, = 0.18 m, = 0.40 m. After specifying the steel error = 0.06 m, = 0.03 m, = 0.25 m. The analysis of the unknown results confirms the improvement of the accuracy of coordinate determination by specifying the values of RMS relative to those obtained in the software package Models and the proposed algorithm. Scientific novelty and practical significance. An algorithm has been developed that makes it possible to determine the value of EEO using software without the use of special software for digital image processing. First of all, it makes it possible to improve the accuracy of EEO determination for digital images obtained from UAVs and allows to significantly expand the range of tasks using UAVs.

Результаты лабораторных испытаний подводной навигационной системы для аппаратов экологического контроля

An urgent task facing the developers of unmanned underwater vehicles (UUVs) (autonomous underwater vehicles, remotely operated underwater vehicles) is to improve the accuracy of determining the output navigation parameters: orientation angles, linear velocities and location coordinates. The systems for determining the course and attitude position (Attitude and Heading Reference Systems – AHRS) and spatial positioning systems, which are supposed to equip the UUV, should not be expensive, but technologically suitable for mass production with acceptable coordinate determination accuracy. At the first stage of the research, a prototype of the navigation platform with software for it was developed and manufactured, on which experimental data from the measuring channels were obtained in laboratory conditions, and then their preliminary processing was carried out. The analysis of existing methods for increasing the accuracy of determining the output navigation parameters of unmanned underwater vehicles showed that, despite their dynamic development and constant improvement, the error in calculating coordinates when using MEMS sensors remains high and unstable. The use of an additional hydrostatic tilt unit in the navigation platform will make it possible to compensate for the errors of MEMS sensors, which require constant correction during their stable operation, unfortunately, only for a short period of time. The analysis of typical errors of MEMS sensors is carried out. The deterministic part of the error of these sensors can be eliminated by calibration, and to estimate the stochastic errors, we used the Allan variation. The obtained error values will be used in the future to form the Kalman filter of the resulting system.

ACCURACY COMPARISON OF ALGORITHMS FOR DETERMINATION OF IMAGE CENTER COORDINATES IN OPTOELECTRONIC DEVICES

Accuracy in determination of coordinates for image having simple shapes is considered as one of important and significant parameters in metrological optoelectronic systems such as autocollimators, stellar sensors, Shack-Hartmann sensors, schemes for geometric calibration of digital cameras for aerial and space imagery, various tracking systems. The paper describes a mathematical model for a measuring stand based on a collimator which projects a test-object onto a photodetector of an optoelectronic device. The mathematical model takes into account characteristic noises for photodetectors: a shot noise of the desired signal (photon) and a shot noise of a dark signal, readout and spatial heterogeneity of CCD (charge-coupled device) matrix elements. In order to reduce noise effect it is proposed to apply the Wiener filter for smoothing an image and its unambiguous identification and also enter a threshold according to brightness level. The paper contains a comparison of two algorithms for determination of coordinates in accordance with energy gravity center and contour. Sobel, Pruitt, Roberts, Laplacian Gaussian, Canni detectors have been used for determination of the test-object contour. The essence of the algorithm for determination of coordinates lies in search for an image contour in the form of a circle with its subsequent approximation and determination of the image center. An error calculation has been made while determining coordinates of a gravity center for test-objects of various diameters: 5, 10, 20, 30, 40, 50 pixels of a photodetector and also signalto-noise ratio values: 200, 100, 70, 20, 10. Signal-to-noise ratio has been calculated as a difference between maximum image intensity of the test-object and the background which is divided by mean-square deviation of the background. The accuracy for determination of coordinates has been improved by 0.5-1 order in case when there was an increase in a signal-to-noise ratio. Accuracy improvement due to increase of a diameter in a test-object is typical for large signal-to-noise ratios: 70 or more. The conducted investigations have made it possible to establish that the algorithm for determination of coordinates of the energy gravity center is more accurate in comparison with contour methods and requires less computing power (for the MatLab software package), which is related to discreteness while determining a contour.

The study of a new family of phase masks for three-dimensional fluorescence nanoscopy

The question of the axial coordinate determination accuracy is quite sophisticated in far field 3D fluorescence nanoscopy. The accuracy of a point emitter axial coordinate reconstruction depends among other things on the conversion efficiency of the phase mask and the microscope objective instrumental function. It was found that the instrumental functions of different microscope objectives differ significantly from each other, most have a strongly non-uniform spatial distribution of the radiation intensity in a parallel beam created by an objective focused on a point emitter. It was shown that taking into account the actual microscope objective instrumental function when calculating the phase masks allows to increase significantly the axial coordinate reconstruction accuracy.

Improvement of Ultrasound-Based Localization System Using Sine Wave Detector and CAN Network

This paper presents an improved indoor localization system based on radio frequency (RF) and ultrasonic signals, which we named the SNSH system. This system is composed of a transmitter mounted in a mobile target and a series of receiver nodes that are managed by a coordinator. By measuring the Time Delay of Arrival (TDoA) of RF and ultrasonic signals from the transmitter, the distance from the target to each receiver node is calculated and sent to the coordinator through the CAN network, then all the information is gathered in a PC to estimate the 3D position of the target. A sine wave detector and dynamic threshold filter are applied to provide excellent accuracy in measuring the range from the TDoA results before multilateration algorithms are realized to optimize the accuracy of coordinate determination. Specifically, Linear Least Square (LLS) and Nonlinear Least Square (NLS) techniques are implemented to contrast their performances in target coordinate estimation. RF signal encoding/decoding time, time delay in CAN network and math calculation time are carefully considered to ensure optimal system performance and prepare for field application. Experiments show that the sine wave detector algorithm has greatly improved the accuracy of range measurement, with a mean error of 2.2 mm and maximum error of 6.7 mm for distances below 5 m. In addition, 3D position accuracy is greatly enhanced by multilateration methods, with the mean error in position remaining under 15 mm. Furthermore, there are 90% confidence error values of 23 mm for LLS and 20 mm for NLS. The update in the overall system has been verified in real system operations, with a maximum rate of 25 ms, which is a better result than many other existing studies.

The use of hand-held GPS receivers for the identification of objects in a wooded area.

This paper is of a research – cognitive feature. It presents a methodology for the identifi cation of point objects (trees) in a wooded area, having an average degree of terrain details condensation and small denivelation of the terrain. The applied methodology was based on the use of hand-held GPS receivers with navigation applications and functions. The advantage of the presented method is the speed and relatively low cost of development. In the economic and technical aspect the presented method for identifying trees may be applied in practice, eg. by the forest service. (Of course, using one of three types of receivers, and not all at the same time – as has been the case for the research). It can be used not only for labeling or identifi cation of individual species of trees, but for example feeding grounds, waterholes and any peculiarities occurring in the area. In addition, positioned and placed on the local thematic maps (eg. travel maps) places particularly worth a look or even those that should be avoided due to the risk of, which may occur in them, may aff ect the improvement of the quality of tourist information. They can also serve the purpose of the promotion of the region. Navigation devices used in the fi eld and described in this publication provide the accuracy of coordinates determination (positioning) even of 2–3 meters [4] for some point objects and can be used for updating the maps and thematic databases of topographic objects.

A probabilistic approach to selecting the significant parameters of filtering signals during acoustic-emission diagnostics of technical objects

The localization of discrete acoustic-emission (AE) signals in the process of inspection often has a low accuracy. A probabilistic approach for evaluating the coordinates of each AE signal is proposed. It is intended to detect local areas in the background of noises or distributed AE sources. This approach is based on the probability of determination of the error as a function of other measured parameters of an AE signal. In particular, the relationship between the coordinate determination accuracy and the maximal amplitude of the signal and the time of its rise on a real object is considered.

Inaccuracy of coordinate determined by several detectors' signals

For any position sensitive detector (PSD) the crucial characteristic for using as tracking or imaging detector is the accuracy of coordinate determination. Position resolution of PSD is closely connected not only with energy resolutions of spatially distributed sensors, but also with correlations between sensors' signal fluctuations. In this paper, the general relation between the position resolution of PSD and sensors' energy resolutions, which accounts for correlations between fluctuations, was derived. Using this general relation, the mean square deviation of reconstructed particle coordinate for PSD with two and three outputs were obtained. Experimental calibration data and a rather simple procedure of data processing based on derived formulae allow, without any technical improvement of position sensitive detector, significantly improve its position resolution.

Forecasting Characteristics of User Equipment in Space Navigation Systems

A method is proposed for predicting the parameters characterizing the metrological characteristics of user equipment in space navigation systems. The method uses an interval form of expression for the measurement accuracy and it estimates not only the accuracy of the measurements but also provides an estimate of the confidence in it. Solutions are provided for the commoner cases of initial specifications for the accuracy of coordinate determination.

Strip detector for short-range particles

A silicon strip detector for the coordinate determination of short range charged particles, particularly heavy ions, has been developed and investigated. The detector has 28 p +n strips made by ion implantation, the pitch is 250 μm and the interstrip distance 50 μm. The coordinates of particles incident between adjacent strips were determined by a two-dimensional amplitude analysis of the charges collected on neighboring strips. Irradiation with α-particles of 226Ra and a scanning laser beam was used. A coordinate determination accuracy better than 1 μm was obtained. In contrast to minimum ionizing particles the plasma tracks of short range particles have higher carrier densities and are located in an inhomogeneous region of the detector. The study of the charge collection times have indicated the essential role of the drift of charges in the inhomogeneous electrical field dependent on the detector geometry, the inhomogeneity of silicon and the built-in charge in the passivating oxide layer between p +n strips.

Strip detector for short-range particles

A silicon strip detector for the coordinate determination of short-range charged particles, particularly heavy ions, has been developed. The detector has 28 p/sup +/n strips made by ion implantation. The pitch is 250 mu m, and the interstrip distance is 50 mu m. The coordinates of particles incident between adjacent strips are determined by two-dimensional amplitude analysis of the charges collected on neighboring strips. Irradiation with alpha -particles of /sup 226/Ra and a scanning laser beam was used. A coordinate determination accuracy of better than 1 mu m was obtained. In contrast to the minimum ionized particle, the plasma tracks of short-range particles have higher carrier densities and were located in the inhomogeneity region of the detector. The study of the charge collection times has clarified the essential role of the drift of charges in an inhomogeneous electrical field, dependent on the detector geometry, and the inhomogeneity of silicon and built-in charge in passivating the oxide layer between the p/sup +/n strips.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A Comparison between Magnetic Resonance Imaging and Computed Tomography for Stereotactic Coordinate Determination

The spatial accuracy of magnetic resonance imaging (MRI) has not been established for stereotactic surgery. Magnetic susceptibility artifacts may lead to anatomical distortion and inaccurate stereotactic MRI coordinates, especially when targets are in regions of the brain out of the center of the magnetic field. MRI-guided stereotactic localization, however, provides better multiplanar target resolution than is available with computed tomographic (CT) scanning. Therefore, we compared the accuracy of stereotactic coordinates determined by MRI and CT studies in 41 patients (53 targets). Coordinates were measured in each plane and as vector distances between the target and the center of the stereotactic frame on axial or coronal MRI studies. Absolute axial plane MRI and CT distances varied an average of 2.13 +/- 1.59 mm. The mean difference in measurements in the X (left-right) dimension was 1.19 mm and 1.55 mm in the Y (anterior-posterior) dimension. Central targets (located less than 2 cm from the frame center) had a mean MRI-CT difference of 2.09 +/- 1.79 mm; peripheral targets (greater than 2 cm from the frame center) differed by 2.17 +/- 1.3 mm. The voxel volumes were calculated for all compared images. Although differences between the physical properties of data acquisition with each imaging modality could explain the observed CT-MRI discrepancies, a 1-pixel difference in target selection could account totally for all the variance observed. MRI field strength (0.5 vs. 1.5 T) did not correlate with coordinate determination accuracy. We conclude that MRI-guided stereotactic localization can be used with confidence for most diagnostic, functional, and therapeutic stereotactic procedures.