Artifact-based calibration and performance verification of the MScMS-II

Large scale measuring systems, i.e. measuring systems characterized by a measurement volume from some meters up to some hundreds of meters, are gaining importance in industry to check large parts or track the position of automated vehicles. In contrast with classical monolithic measuring systems, modern large scale measuring systems are constituted by constellations of sensors able to track the position of objects by triangulation or trilateration. This new design allows a greater system flexibility, scalability, and portability, together with a general reduction of costs. The MScMS-II is a large scale measuring system based on infrared triangulation. It has been designed to guarantee the maximum flexibility and reconfigurability, so every set-up procedure has been reduced as much as possible, so that its deployment and calibration requires a short time. However, its accuracy could benefit of a more complete volumetric calibration through the definition of a model of the volumetric error to be compensated. This work continues the one proposed at the CAT2012 conference [1]. An artifact has been developed which is constituted by a series of infrared reflective spheres, thus being well visible by the MScMS-II system. It has been calibrated with a ~1 µm uncertainty. It carries two series of balls. A pair of spheres with a reciprocal distance equal to 800 mm can be used for system calibration. A series of couples of balls with reciprocal distances equal to 200, 400, 600, 800, and 1000 mm respectively can be adopted for performance verification similarly to what is suggested in the ISO 10360 series of standards for CMMs. Experimental results are proposed for the calibration and performance verification procedure of the MScMS-II system.