The results obtained by five laboratories in the determination from dimensional measurements of the effective areas of two gas-operated 10 cm2 piston-cylinder assemblies are presented. These measurements were carried out as phase A1 of a key comparison in the pressure range 0.05 MPa to 1 MPa under the auspices of the Consultative Committee for Mass and Related Quantities (CCM) of the Comité International des Poids et Mesures. The participants performed diameter, straightness and roundness measurements on each piston and cylinder bore and calculated the effective area of each piston-cylinder assembly using their own methods. The differences between diameters determined by the institutes are systematic and often greater than the uncertainties claimed by the participants. Nevertheless, all calculated effective areas agree with the reference values determined within the expanded uncertainties with a coverage factor 2, most of them even within their standard uncertainties. The choice of calculation method seems to be less important than the dimensional data themselves. The effective areas determined from the dimensional measurements are compared with those obtained in cross-float experiments with national pressure standards, in a comparison referred to as phase A2 and reported in a separate paper.
The TELEMETER is a high precision positional tracking device that works by triangulation over the angular measurements provided by two or more TELEGONIOMETERS; each of the latter is composed by a TV camera with a teleobjective, looking at the working space through a pair of orthogonal mirrors. A problem rising with this kind of structure is the automation of the initial pointing of the Telegoniometers on the target. To this aim, we propose to add a third camera, with a wide-angle lens framing the whole workspace, to provide the line of sight on which the target must lie. In this work we present this "Three-eyes" structure and discuss its calibration, as well as the problems related to the strategy for scanning the line of sight and for detecting the tracking condition. Two examples of possible application of the Three-eyes system, respectively to robot qualification and to autonomous navigation, are also presented.
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