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Research and development

Working Group 1.71

Research and development for the establishment and investigation of standard methods of measurement and standard measuring devices for the realization and dissemination of the units and associated scales of motion quantities

In research and industry, the requirements for the measurement of time-dependent mechanical quantities have significantly increased over the past years. It is now required on the national and international levels that dynamic measurements be traced back to the units of acceleration and angular acceleration, and to the units of other physical quantities, which have been realized by dynamic methods. For this purpose, standard measuring devices are needed as national standards, which generate and accurately measure these quantities at special time dependencies. In addition to the exciter for the generation of the motion quantities acceleration and angular acceleration and the laser interferometer for precise measurements, the standard measuring device must comprise a highly accurate device for the measurement of electrical voltages or charges put out by transducers for motion quantities.

Over the last two decades, various standard measuring devices (national standards) have been developed for the realization of the units of the physical quantities of linear and angular acceleration. They allow transducers, measuring chains and measuring instruments for motion quantities (e.g. acceleration and angular acceleration) to be calibrated over wide measurement ranges and with high accuracy (i.e. small uncertainty). The standard measuring devices which have been developed can be used to investigate and calibrate transducers for acceleration, velocity, displacement, angular acceleration, angular velocity and rotation angle.

The research and development work done so far has produced seven standard measuring devices which, as national standards, generate translational or rotational motions in a desired degree of freedom (rectilinear or around a fixed axis), at sinusoidal or shock-shaped time-dependency, and measure them with high accuracy by laser interferometry:

These standard measuring devices mainly consist of an air-borne electromechanical or mechanical exciter and an interferometric measurement system. Special measurement methods and computer-aided signal processing procedures are applied to accurately measure the motion quantities and to determine transducer characteristics, in particular within the framework of the dissemination of the units of translational and rotational motion quantities through primary calibrations of reference and transfer standards in compliance with the international standards.

Moreover, the multi-component acceleration standard measuring device has been developed as a novel standard measuring device to be used for the realization of motion quantities, simultaneously in different directions (translational in three orthogonal directions X, Y, Z, and rotational around the Z-axis).

Research and development in the area of the dissemination of the units have focused on the identification of metrological characteristics (e.g. spurious sensitivities and long-term stability) of commercial transducers and measuring instruments which have been used as, or are considered candidates for standards. Another task undertaken is the development of special standards which are not commercially available. Theoretical and experimental investigations are performed to evaluate the uncertainty of measurement in the realization and dissemination of the units and associated scales of acceleration, angular acceleration and derived motion quantities.