The dependence of coordinate measurements error of the geometric elements shape characteristics of products on the control points number

The issues of estimating the error of coordinate measurements of the shape characteristics of geometric elements of products depending on the number of control points, taking into account a given confidence probability, are considered. Analytical models are proposed for estimating the error based on a priori data, similar to estimating uncertainty by type B. The correspondence of model and experimental results is verified by the Monte Carlo method using a specially developed program in VBA and the library functions of the Statistical Analysis package of the Microsoft Excel program. Such a characteristic of the shape of the part as roundness is investigated. The influence of the parameters of regular structures associated with the features of the technological processes of manufacturing the part on the parameters of the distribution function of the coordinates of the control points is revealed. Fourier analysis is used to identify and quantify regular structures on the surface of the part. The sources of error that have a significant impact on the results of measurements of the shape characteristics of geometric elements of products are given. Based on the results of statistical calculations, the dependence of the measurement error of the shape characteristics on the number of control points is analyzed, the scope of application of analytical formulas for estimating the error of single measurements for a given confidence probability is determined. The article is intended for specialists in the field of practical coordinate metrology and related fields.

Lidar virtual models for seismic exploration

Seismic exploration is important for development of new fields and the resumption of production at old areas of oil production. These works involve studying of underground geological structures using seismic profiling and seismotomography methods. In fact, detailed information about the territory is necessary for almost every participant in the process—to find the optimal routes for movement on terrain, to optimize the volume of forest felling on profiles, for georeferencing and checking coordinate measurements at points, etc. The availability of spatial data is also important for increasing the level of safety and trouble-free operation during work. One of possible solutions is to perform field surveys using aerial photography and airborne laser scanning, followed creation of virtual models based on them with instrumentation adapted to the specifics of these works. Modern GIS, with all their development, has number of disadvantages. It is difficult to use GIS by non-specialists; full-featured GIS are expensive, and free solutions has limited analysis functionality and can’t make good 3D visualizations, it is difficult to protect spatial information from unauthorized copying. These problems can be solved without using classic GIS packages. Instead, it is proposed to use virtual environments closed from editing and access to the original data. Test area of 69 km2 in the Khanty-Mansiysk Autonomous Okrug was selected for testing virtual modeling technologies. LIDAR and aerial photography datasets were obtained, and subsequent processing of the resulting was done, forming highly-detailed virtual environment. The article discusses the main features and functionality of this model.

DETERMINATION OF GEOMETRICAL PARAMETERS OF GAS TURBINE BLADES BASED ON COORDINATE MEASUREMENT BY STRUCTURAL AND PARAMETRIC ANALYSIS METHODS

A method for determining the parameters of the turbine blades geometry (angles of the inlet and outlet edges, thickness, etc.), as well as the coordinates of the centers of gravity of the blades (height) according to the coordinate measurements of the profiles is proposed. These parameters are used to evaluate the gas-dynamic efficiency of the blade row and the strength characteristics of the turbine blades on the basis of one-dimensional and two-dimensional models widely used in engineering practice.

Evaluation of the degree of fitting of a curvilinear hole and stub machined on a CNC milling center

The method of evaluating the accuracy of fitting a curvilinear hole-stub pair is presented. The next stages of the process were presented, including: machining of elements, coordinate measurements of machined parts, analysis of measurement results. A method to improve the degree of fitting of the hole-stub pair is proposed.