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On statistical estimations of vehicle speed measurements

Skeivalas Jonas, Paršeliūnas Eimuntas, Putrimas Raimundas, Šlikas Dominykas

Metrology and Measurement Systems

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2019

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Vol. 26, nr 3

551--559

EN

The accuracy of vehicle speed measured by a speedometer is analysed. The stress on the application of skew normal distribution is laid. The accuracy of measured vehicle speed depends on many error sources: construction of speedometer, measurement method, model inadequacy to real physical process, transferring information signal, external conditions, production process technology etc. The errors of speedometer are analysed in a complex relation to errors of the speed control gauges, whose functionality is based on the Doppler effect. Parameters of the normal distribution and skew normal distribution were applied in the errors analysis. It is shown that the application of maximum permissible errors to control the measuring results of vehicle speed gives paradoxical results when, in the case of skew normal distribution, the standard deviations of higher vehicle speeds are smaller than the standard deviations of lower speeds. In the case of normal distribution a higher speed has a greater standard deviation. For the speed measurements by Doppler speed gauges it is suggested to calculate the vehicle weighted average speed instead of the arithmetic average speed, what will correspond to most real dynamic changes of the vehicle speed parameters.

2

Diagnostyka dokładności wskazań multimetrów cyfrowych

Tabisz R. A.

Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska

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2016

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nr 3

36--39

PL

Opisano sposoby obliczania błędu maksymalnego dopuszczalnego (BMD) oraz jego dwóch składowych: multiplikatywnej (BDmul) i addytywnej(BDadd). Wyjaśniono zasady diagnostyki dokładności wskazań multimetrów. Zaproponowano wykorzystanie wyników wzorcowania do wyznaczania funkcji korekcyjnej umożliwiającej redukowanie błędów systematycznych. Potwierdzono wynikami badań eksperymentalnych możliwość obliczania metodą typu B niepewności wyników pomiarów uzyskanych po korekcji błędów systematycznych, na podstawie tylko składowej addytywnej (BDadd).

EN

Methods of calculating maximum permissible error (MPE) and its two components: multiplicative (PEmul) and additive (PEadd) are described. Principles of accuracy diagnostic of multimeters' indications are explained. Use of calibration results to determine corrective function that allows for reduction of systematic errors is proposed. Presented results of experimental tests prove that calculating uncertainty of measurement results obtained after the correction of systematic error - with use of Type B method - can be based solely on additive component (PEadd).

3

Accuracy of the photogrametric measuring system for large size elements

Grzelka M., Budzik G., Marciniak L., Gapiński B.

Archives of Foundry Engineering

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2011

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Vol. 11, iss. 2 spec.

75--80

EN

The aim of this paper is to present methods of estimating and guidelines for verifying the accuracy of optical photogrammetric measuring systems, using for measurement of large size elements. Measuring systems applied to measure workpieces of a large size which often reach more than 10000mm require use of appropriate standards. Those standards provided by the manufacturer of photogrammetric systems are certified and are inspected annually. To make sure that these systems work properly there was developed a special standard VDI / VDE 2634, "Optical 3D measuring systems. Imaging systems with point - by - point probing. " According to recommendations described in this standard research on accuracy of photogrametric measuring system was conducted using K class gauge blocks dedicated to calibrate and test accuracy of classic CMMs. The paper presents results of research of estimation the actual error of indication for size measurement MPEE for photogrammetric coordinate measuring system TRITOP.