Design and development of a new large-scale metrology system: MScMS (Mobile Spatial coordinate Measuring System)

This thesis arises from the research activity developed at the Industrial Metrology and Quality Engineering Laboratory of DISPEA – Politecnico di Torino, on a new system prototype for dimensional measurement, called Mobile Spatial coordinate Measuring System (MScMS). MScMS determines dimensional features of large-size objects and has been designed to overcome some limits shown by other widespread measuring sets used nowadays, like Coordinate Measuring Machines (CMMs), theodolites/tacheometers, photogrammetry equipments, GPS based systems, Laser Trackers. Basing on a distributed sensor networks structure, MScMS can accomplish rapid dimensional measurements, in a wide range of indoor operating environments. It consists of distributed wireless devices, communicating with each other through radiofrequency (RF) and ultrasound (US) transceivers. This frame makes the system easy to handle and to move, and gives the possibility of placing its components freely around the workpiece. The wireless devices − known as “Crickets” − are developed by the Massachusetts Institute of Technology (MIT). Being quite small, light and potentially cheap (if mass produced), they fit to obtain a wide range of different network configurations. These features make the new system suitable for particular types of measurement, which can not be carried out, for example, by conventional CMMs. Typical is the case of large-size objects which are unable to be transferred to the measuring system area (because of their dimensions or other logistical constraints) and thus require the measuring system to be moved to them. In the dissertation the system is described exhaustively and characterized through practical experiments. Then, the system is compared to classical CMMs and the indoor-GPS (iGPS), an innovative laser based system for large-scale metrology. Finally, future directions of this research are given.