Analysis of calibration data of position of circular scale strokes

There is a wide variety of application of circular scales and rotary transducers used in micro-positioning devices for mechatronic measuring and control instruments. Their accuracy has direct influence on the accuracy of positioning or precision displacements of piezoelectric devices. There are a vast number of methods for accuracy calibration of the circular scales and rotary encoders. One of the modified methods (constant angle setting in full circle with multiple turn) has been proposed by the authors in this paper. Practical implementation of the method is described herein together with the analysis of the scale strokes biases (systematic errors) and random errors calculation. Values of scale strokes biases obtained by calibration of scale using the proposed method are compared with the reference values obtained by means of the multiangular prism (polygon) and photoelectric autocollimato

Measurement of angular displacement by means of laser scanner

The paper deals with the investigation of laser scanning instrument‘s possibility to be used for determination of the angular position or displacement of the object. Laser scanners are used widely in geodesy, structural and machine engineering areas. Such application gives new opportunities for measurement of an angle position of object in such places and positions, where usually used angle measuring instruments are not available or not possible to use. In this paper the determination of angular position of rotary device by means of plate freely placed on the rotating part and the laser scanning instrument is presented together with some experimental results of such layout applicatio

Modal analysis and experimental research into improved centering-leveling devices

Centering–leveling devices are often used together with rotary tables to improve measuring process in various fields of metrology. The most important factor of measurement quality – accuracy – is affected by numerous external and internal factors. To ensure the optimum quality of measurements, several factors have to be well known and thus taken into account in the final measurement to minimize their influence. Analysis of structural dynamics provides data on sensitivity as well as an appropriate method to verify the analytical model. The paper deals with an analysis of structural dynamics of a plain structure centering–leveling device by performing appropriate modal analysis. The experimental setup for vibration monitoring and measurement principle underpinning the work is described in the paper. Measurement results of table dynamics as well as a comparison of theoretical and experimental modal shapes are discussed

Investigations into the accuracy of angle calibration

Technical possibilities to create equipment for the calibration of flat angles are discussed in the article. The angular standard measure, the radian, has not been realised as a standard unit until now. Nevertheless, the unit of angular measure in degrees is used as the geometric measure of length in geodesy, machine engineering and other branches of industry – by multiangular prisms – polygons with an autocollimator, rotary tables, circular scales, etc. It should be noted that these angle measures are calibrated against the upper level measures (etalons) only at the several intervals depending on the number of sides (angles) of the polygon or the other standard measure. The methods of calibration of constant angle value in full circle are used as well. At the same time geodetic instruments, rotary tables of metal cutting tools and instruments, rotary encoders have a great number of discrete values. These values between the calibrated points remain unknown during calibration. The information received during calibration relative to all the information available can be evaluated using information entropy. The equipment of calibration permitting to select significantly more information would be essential for better accuracy assurance of instruments used in machine engineering, geodesy, building structures. Theoretical and technical background for justifying and developing such equipment for angular accuracy calibration is presented here. A modern scientific and technical background validates this concept. Kampų kalibravimo tikslumo tyrimas Santrauka. Straipsnyje nagrinejamos technines galimybes sukurti plokščioj o kampo kalibravimo irengini tiksliems kampu matams kalibruoti. Plokščiojo kampo vienetas radianas iki šiol nera laikomas kampo mato etalonu. Kampo matas laipsniais gali būti nesunkiai sukuriamas ir atkartojamas geodezijoje taikant geometrinius ilgio matus, o mašinu gamybos ir kt. pramones šakose – naudojant daugiakampes prizmes (poligonus) su autokolimatoriais, pasukamuosius optinius stalus, apskritimines skales ir pan. Reikia pažymeti, kad plokščiuju kampu matai kalibruojami tik retais intervalais, tiek, kiek turi briaunu daugiakampe prizme arba kitas pirminis matas, taikomas kaip etalonas. Taip pat šiam tikslui yra taikomi pastovaus kampo kalibravimo visame apskritime metodai. Geodeziniams prietaisams, stakliu pasukamiesiems stalams ir keitikliams būdinga didelis rodmenu diskretumas. Ju tarpine verte bei paklaidos lieka nenustatytos, taip pat išlieka daug nežinomos informacijos vertinant informacines entropijos metodu. Didesnio diskretumo ir reikiamo tikslumo plokščiojo kampo kalibravimo irenginys padetu užtikrinti didesni gaminiu, statybiniu darbu bei geodeziniu matavimu tiksluma ir informatyvuma. Čia pateikiamas teorinis ir techninis plokščiojo kampo kalibravimo irenginio tikslingumo pagrindimas ir, remiantis turimu techniniu bei moksliniu potencialu, aptariamos jo sukūrimo galimybes. Raktažodžiai: kalibravimas, apskritiminė skalė, etalonas, kampas, tikslumas. First published online: 03 Aug 201

Information entropy determination in scales measurement including mechatronic approach

"Analysis of information entropy of mechatronic measuring systems, computer modelling; research of the accuracy of multiparameter systems and the solutions for determination of the deviations of those parameters for the purpose of application it to the adaptive correction and for assurance of mechatronic control of the system are presented in the paper. The mechatronic means for correction of systematic errors of information-measuring systems including measurement of linear and circular scales are presented. An application of active materials for smart correction by piezoactuators is given

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. Article in English Stendo geodezinių prietaisų plokščiajam kampui kalibruoti Santrauka. Pastaruoju metu tikslūs geodeziniai prietaisai yra plačiai naudojami geodezijoje, statyboje, topografijoje, mašinų gamyboje it t. t. Daugumos šių prietaisų veikimo principas pagrįstas tiksliu kampų matavimu. Tokie prietaisai – teodolitai, elektroniniai tacheometrai ir kt. Atlikti šių prietaisų patikrą ir kalibruoti – gana sudėtingas techninis uždavinys. aprašomas naujai sukurtas įrenginys tokiems geodeziniams prietaisams kalibruoti ir tikrinti, jo kūrinio eiga bei pradiniai tikslumo tyrimai

The application of the bivariate distribution and mutual information in measurement

The measuring systems, such as those used in coordinate measuring machines (CMMs), laser interferometers, linear or rotary encoders, etc., feature of huge amount of information indicating the position of the object under control. This information is subject for verification or metrological calibration during some periods in service. On the other hand, there are no means for verifying every digit of output information, and the great quantity of information consisting of millions of values is left with its errors undetermined. Expression of the result of measurement (including the calibration) of a measuring system supplementing it by the parameter of information entropy is proposed in the paper. The uncertainty expression in the result of measurement in the plane and in the volume is presented here with the parameter of information entropy that shows the portion of data assessed

Analysis of discretisation strategy for area and space measurement

Measurement strategy is discussed in the article. It is important to optimise the data selection (sampling) from the object for the determination of its geometrical features within some limits of accuracy. The minimal and maximal intervals of measurement must be selected ensuring the maximal efficiency of operation and the accuracy as well. In machine engineering the typical case is in the calibration of coordinate measuring machines (CMMs) as it is a quite complicated task because of the variety of accuracy parameters to be checked and the high accuracy that must be assured. Some new techniques for the two‐ and three‐dimensional measurements are discussed in this paper leading to a more efficient calibration process. This is relevant to machine engineering where geometric accuracy parameters are to be determined, to the geodetic measurements where slopes of terrain, area flatness and volumetric features are surveyed, in structural engineering, etc. Article in Englis

Accuracy calibration of the bars of levelling meters

Precision levelling is one of the most common geodetic measuring operations. The most modern geodetic instruments are quite sophisticated digital instruments that are supplied by photoelectric sensor arrays and optical–electronic cameras that fix the height values of terrain according to the position of the levelling meter that is placed on it. The marks on the levelling meters are also modified and consist of coded strokes put on the meter’s surface in a specific order. The accuracy of the performance of all the measuring equipment depends mostly on the accuracy of the position of those strokes. This paper deals with an analysis of an accuracy calibration of levelling meters, its methods and means of evaluation.