Fig 2 - uploaded by Kenneth T V Grattan
Content may be subject to copyright.
Source publication
The analysis of 2D measurement methods and means is presented. The actual optical-electronic devices using bar codes are discussed. The correlation functions of measuring and reference codes in the electronic level instrument are calculated showing possible errors in height determination. The new electronic level design is proposed simplifying the...
Context in source publication
Context 1
... new structure of the measuring instrument is proposed using a very simplified bar-code meter and the reading device operating without correlation value assessment (Fig. 2). The main parts of the instrument: 1- optical levelling instrument, 2 -base, 3 -bar meter, 4 - rotary encoder (angular ...
Similar publications
This paper presents a description of modified booth's algorithm for multiplication two signed binary numbers. Radix-2 booth's algorithm is explained, it is then identified that the main bottleneck in terms of speed of the multiplier is the addition of partial products. Radix-4 Booth's algorithm is presented as an alternate solution, which can help...
Citations
... Elektroniniuose nivelyruose taikoma automatizuota kodinių niveliavimo matuoklių (brūkšninių skalių) atskaitų registravimo prietaiso indikatoriuje sistema. Kodinės matuoklės skaitmeninei atskaitai gauti naudojamas tiesinis detektorius ir taikomi koreliacijos (nivelyras Leica Wild NA 3003), geometrinis (Zeiss DiNi 10/20) bei fazinis (Topcon DL 101/102) metodas (Menzel 1999;Skeivalas, Giniotis 2000;Grattan et al 2003;Giniotis, Skeivalas 2002;Lopez-Alonso, Alda 2003;Takalo, Rouhiainen 2003;NA 2002NA 1997. Kovariacijos nustatymo tikslumas priklauso nuo tiesinio detektoriaus fotodiodų (pikselių) matmenų, jų skaičiaus bei detektoriaus jautrio funkcijos. ...
Pristatoma kodiniu niveliavimo matuokliu kalibravimo tikslumo, taikant kovariaciniu funkciju teorija, analize. Kodiniu matuokliu skaitmeniniai vaizdai, gauti skaitmeniniu fotoaparatu, apdorojami pagal sudaryta kompiuterine programa Matlab 7 programinio paketo operatoriu aplinkoje ir formuojami stacionariosios atsitiktines funkcijos pavidalu. Siu funkciju auto- ir tarpusavio kovariacines funkcijos nagrinejamos esant ivairiems vaizdo pikseliu kvantavimo intervalams. Pagal tai galima ivertinti atitinkamu matuokliu kodiniu bruksniu tarpusavio nuokrypius etalonines matuokles kodiniu bruksniu tarpusavio nuokrypiu atzvilgiu. Niveliavimo matuokliu kodinius bruksnius imanoma kalibruoti 1-2 pikseliu tikslumu.
... In most cases, subsequent comparison with an identical part of the whole scale of bar code rod stored in the memory of instrument is then carried out. The manufacturers that produce digital levelling instruments developed their own code and processing methods (Ingensand, 1999;Schneider and Dixon, 2002;Radcliffe, 1999;Grattan et al., 2003). The issue of the influence of the rod illumination when measuring by digital level instruments is quite broad. ...
Since the digital levels operate on the principle of image processing of the bar code of levelling rod, recorded by a CCD sensor, the proper lighting (i.e. illumination of the bar code) is important to achieve accurate results. The prevention of inappropriate lighting conditions is important for the correct recording of the image of bar code section. This paper examines the systematic error as a function of the angle of incidence at which an bar code is illuminated by artificial lighting in low light conditions. Further, the procedure of measurements and the analysis of results for the identification of such errors is proposed. The results of experimental measurements highlight the inappropriateness of bar code illumination at an angle of incidence of more than about 45 °. From the practical measurements, it was found that the angle of incidence 55 ° corresponds to an error of about 0.02 mm, which is twice as much as the resolution of the height measurement determined by the manufacturer.
Quality of results of physical measuring system is analysed mathematically in this publication. Analysis of information amount function shows that information amount on measurement errors obtained from closing error is decreasing when accuracy of measurement is increasing, while calibration errors of the system stay constant. Errors of calibration describe information amount obtained during the time of measurement. Based on curvature of information amount function the optimal measurement accuracy variant is obtained when the ratio of errors of measurement and calibration is equal to three. The impact of tolerance on measurement information amount is demonstrated.
Optical-electronic leveling devices using a staff with bar codes are discussed. The reading of the staff is taken along its longitudinal axis; the distance to the staff and its vertical position are determined by the readings of a translational transducer connected to the optical system during its focusing on the bars of the staff. The height is determined according to coded signals of the image of the bars transferred into an array of photoelectric cells in the instrument and processed by a microprocessor to the height values. Three main types of image processing are used in various types of digital levels: a correlation method, a geometric method, and a phase method. The correlation functions of measuring and reference codes in the electronic level are calculated in this paper, showing possible errors of height determination. The information obtained during the measurement shows the relationship between the information entropy received from different values of readings from the staff. A new digital level design is proposed, simplifying the design of the instrument and the staff as well. The principal correlation and error determination equations are given, and diagrams of the new design are included.
Precision levelling is one of the most common geodetic measuring operations. The most modern geodetic instruments are quite sophisticated digital instruments that are supplied with 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 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.
