Measurement accuracy improvement of laser-based CMM

In the last years, a wide attention to the methodologies for the reverse engineering (RE) has been given, as an answer to the increased interest in the industrial and scientific fields. The reverse engineering is always envisaged as a technology focused on the selection of the digitalization equipment and on the software tools for the manipulation of the data and the reconstruction of the surface: the technological aspects are not considered therefore of it the demands work them relating the object. At the Dipartimento di Architettura Urbanistica e Rilevamento of the University of Padova, it is in course the "project Functional Integrated Reverse Engineering", finalized to the realization of a new technological workplace for the reverse engineering of prototypes and industrial products. This ambient consists of hardware technologies, based on a CMM Laser, and of software technologies. A critical aspect, in the phase of reconstruction of geometric feature, is the accuracy of the acquisition system that can be obtained with the precision of the workings and the methods of assemblage. Its however possible to increase the precision of the acquired data by means of the modeling of the geometric errors of the system, and numerous are the relevant scientific contributions. This job describes the application and the elaboration of a mathematical model based on the cinematic of the rigid bodies, for the correction of the geometric errors of the machine of measure to scansion laser used for the acquisition of small archaeological biomedicali and mechanical manufacts.. The model of compensation of the geometric errors is realized with the direct method, measuring the motion of the movement guides using an external device. Every error has been acquired experimentally using a commercial CMM which metrological reference. The proposed model is therefore an elaboration of the direct mapping of the positions assumed from the system in its movements to the inside of the working volume. In the following pages they introduce the mathematical model, the process of acquisition of the experimental data and the analysis of the characteristics of the CMM Laser. Finally they are introduced the results of the validation of the system using a calibrated artefact, specifically realized.