ALBERT WECKENMANN, JOHANNES WEICKMANN

University Erlangen-Nuremberg
Chair Quality Management and Manufacturing Metrology
Naegelsbachstr. 25, 91052 Erlangen, Germany
e-mail: weckenmann@qfm.uni-erlangen.de

OPTICAL INSPECTION OF FORMED SHEET METAL PARTS APPLYING FRINGE PROJECTION SYSTEMS AND VIRTUAL FIXATION

Modern forming technology allows the production of highly sophisticated free form sheet metal components, which are subject to a reversible geometrical deformation caused by residual stress, gravity or variations of the material. This distortion is usually removed during assembly and therefore the part's tolerated parameters have to be inspected in fixed state, which simulates assembly conditions. Today this time-consuming work is done on CMMs (Coordinate measuring machines). Using fast optical measuring systems and virtual fixation, this process chain can be dramatically shortened and in-line measurement seems to be possible in future. Virtual fixation means that at first a workpiece is measured in distorted state without fixation and afterwards the shape in assembled state is simulated by FEM analysis. Thus, workpieces can be inspected with significantly reduced effort.

Keywords: virtual distortion compensation; fringe projection; Finite Elements Method (FEM); optical metrology; inspection process

Full paper (2025kB): M&MS_2006_321.pdf

ANATOLIY A. PLATONOV

Warsaw University of Technology
Institute of Electronic Systems¹
Poland, e-mail: plat@ise.pw.edu

INTELLIGENT CYCLIC ADC. PRINCIPLES OF FUNCTIONING, OPTIMISATION AND ANALYSIS²

The aim of the paper is a presentation of conceptual backgrounds of a new approach to design and analysis of high-efficient intelligent analog-to-digital converters (ADC). Particularities of intelligent conversion, methods of its practical implementation and advantages over conventional methods of conversion are discussed. The analysis is carried out on the example of "intelligent" cyclic ADC (IC ADC), which employ, as the prototype, the architecture of known cyclic ADC developed by Analog Devices Inc. [1, 2]. There is shown the method of extension of the proposed approach for development of more advanced versions of IC ADC with extended range of application and processing possibilities. The paper generalizes the results of previous investigations.

Keywords: cyclic ADC, intelligent conversion, optimisation, ENOB

¹ On leave from Moscow Institute of Electronics and Mathematics, Chair of Cybernetics, Russia.
² The work was presented, in part, at the International Conference on Signals and Electronic Systems (ICSES'2006), Łódź, September 17-20, 2006 [23].

Full paper (294kB): M&MS_2006_335.pdf

KONRAD JĘDRZEJEWSKI¹, ANATOLIY A. PLATONOV<sup>1,2

1</sup>Warsaw University of Technology
Faculty of Electronics and Information Technology, Poland
e-mail: kala@ise.pw.edu.pl
²Moscow Institute of Electronics and Mathematics
Chair of Cybernetics, Russia
e-mail: plat@ise.pw.edu.pl

APPLICATION OF DIGITAL DITHER TO REDUCTION OF FEEDBACK D/A CONVERTERS INFLUENCE ON INTELLIGENT CYCLIC A/D CONVERTERS PERFORMANCE^*

The effect of termination of resolution growth, common for cyclic analogue-to-digital converters (CADCs) the, which appears after a definite (threshold) number of the conversion cycles, is investigated in the paper. The effect is caused by the finite resolution of the D/A converter (DAC) in the feedback chain. In an "intelligent" CADC (IC ADC, [1-6]), the growth of resolution can be restored by adding the digital dithering signal to the signal at the input of the feedback DAC. The dependence of the rate of restored growth of resolution on the distribution and amplitude of the dithering signal is investigated. The results of analysis are verified in advanced simulation experiments.

Keywords: cyclic A/D converters, resolution, ENOB, digital dither

^* The work was supported in part by Grant 3 T 11B 059 29 of the Polish Ministry of Science and Information Society Technologies.

Full paper (1016kB): M&MS_2006_357.pdf

J. CICHOSZ¹, A. KONCZAKOWSKA¹, A. SZATKOWSKI<sup>2

1</sup>Gdańsk University of Technology
Poland, e-mail: alkon@eti.pg.gda.pl
²Pomeranian Academy, Słupsk, Poland

A METHOD OF IDENTIFICATION OF RTS COMPONENTS IN NOISE SIGNALS

Keywords: RTS noise, piece-wise constant approximation.

Full paper (277kB): M&MS_2006_373.pdf

H. M. SIDKI, M. AMER, F. ABD EL AZIZ

National Institute of Standards
Laboratory of Engineering and Precise Optics
Tersa Street, El-Haram, Giza, Code No. 12211, Egypt.
email: hossamsidki@yahoo.com

CALIBRATION OF REFERENCE STANDARD QUARTZ ROTATING PLATES

An accurate linear polarized optical system for calibrating the quartz plate angles is introduced in this work. The quartz plate parallelism and surface roughness are measured using a phase shifting laser interferometer to study their effects on quartz rotation angles which equals to ±18.21 sec. A polynomial regression method is applied to determine and extrapolate quartz rotation angles corresponds to the un-calibrated regions of the visible spectrum. The bi-rotation index values (n_L − n_R) of the quartz plates for all scanned wavelengths are determined applying the calibrated rotation angles. The uncertainty of the calibrations is evaluated, also the combined uncertainty of calibrations for angles (Δβ_t≈ ± 0.09°) that shows the usefulness of this article.

Keywords: quartz rotating plates, phase shifting laser interferometer, polarization optical system

Full paper (457kB): M&MS_2006_383.pdf

G.L. PANKANIN, J. BERLIŃSKI, R. CHMIELEWSKI

Warsaw University of Technology
Institute of Electronic Systems
Poland, e-mail: g.pankanin@ise.pw.edu.pl

SIMULATION OF VORTEX STREET DEVELOPMENT USING MODEL WITH MODIFICATIONS

Two modifications of the analytical model of the vortex street development described in [1] have been proposed and simulated. The first one takes into consideration the movement of the stagnation region accordingly to vortex shedding. Introduction of a tapering duct sometimes used in practical designs instead of the duct of steady cross-section has been also considered. Simulations of both modified models enabled to formulate conclusions concerning the influence of the geometrical parameters on the vortices energy.

Keywords: numerical modeling, Karman vortex street, vortex meter

Full paper (429kB): M&MS_2006_395.pdf

JERZY JAKUBIEC

Silesian University of Technology
Institute of Metrology, Electronics and Automatic Control
Poland, e-mail: jerzy.jakubiec@polsl.pl

SYSTEM OREIENTED MATHEMATICAL MODEL OF SINGLE MEASUREMENT RESULT

Measurements in a system are performed automatically by using data acquisition cards typically consisting of an amplifier, a sample/hold circuit and an analog-to-digital converter. The results obtained from these cards are processed by a program. The processing algorithms are often of sophisticated numerical structure and, in this situation, the determination of inaccuracy of the system output data needs building a system error model. The base of the error model construction should be a model of a single measurement result delivered at the output of the card. The paper presents a model which has been obtained on the basis of an analysis of the quantization process consisting in a direct comparison of the measured quantity with a standard of quantum character. In a measuring system the quantization is realized by an AD converter, which measures a sample of a time-varying input quantity. The assumption that the sampling is performed at any moment enables obtaining the model described in probabilistic categories, which may be the basis of the uncertainty calculation of the system output data.

Keywords: measurement system, data acquisition card, single measurement result model, error model, quantization

Full paper (199kB): M&MS_2006_407.pdf

A. WIORA, J. WIORA, A. KOZYRA

Silesian University of Technology
Institute of Automatic Control, Measurement Systems Group
44-100 Gliwice, Poland
e-mail: wiora@polsl.pl

DYNAMIC MODELS OF ION-SELECTIVE ELECTRODES WITH THEIR ELECTRONIC INTERFACE

Dynamic models of an ion-selective electrode are analysed in this article taking into account the independence of values of its dynamic parameters from the value and direction of activity change. Unfortunately, a complicated mathematical representation of a new model makes the model difficult to be applied in practice. Therefore, some simplifications are made constructing two semi-empirical models: 1) a model with the k parameter and 2) a model basing on two other models well-known from the literature. Verifications of the new models have been performed using the measuring set-up built in the Division of Measurement Systems at the Silesian University of Technology. Obtained results proved that the model with the k parameter completely fulfils the goal of the article − its dynamic parameters are dependent on the slightest degree of the kind of activity step.

Keywords: potentiometry, ion-selective electrode, dynamic models

Full paper (298kB): M&MS_2006_421.pdf

PAWEŁ SWORNOWSKI

Poznań University of Technology
Institute of Mechanical Technology
Poland, e-mail: swornowski@wp.pl

THE INFLUENCE OF INACCURACY OF CALCULATING ALGORITHMS USED IN THE CMMS ON MEASUREMENT RESULTS -FINAL REPORT

The author has devised a test for evaluating the accuracy of calculation algorithms and used it to establish the accuracy of the software of fourteen CMMs offered by world top manufacturers. Using a minimum number of measuring points, the author calculated various geometrical elements with arbitrary shape deviations and the relationships between them, and compared the obtained results with the reference results. The input data were entered from the keyboard to the computer working with a CMM. Therefore the error of the final calculation result was introduced only by the software and the computer, and did not include the errors of the CMM. The computer and the software were treated as a "black box". The same test set was used for all software.

Keywords: coordinate measuring technique, evaluation software, computer simulation

Full paper (320kB): M&MS_2006_433.pdf