Sistema di calibrazione automatica laser scanner con slitta motorizzata e unità di calibrazione master

Nowadays SMEs have a high quality production but relatively small batches respect to current automation technologies that are tailored on big production batches. There is the request to develop innovative methods and tools to increase flexibility and reconfigurability of systems for SMEs; the goal is short delivery time for high quality customized products. Focusing on robotized systems, the need is to decrease programming, set-up and reconfiguration time, like using process parameters auto-tuning. In this paper we disuss a case study of a robotic system for complex surfaces of statues extraction, model digitalization and generation of part program for rapid prototyping or small batch series production. A complete robotic cell was developed based on a milling manipulator equipped with a rotary table and a laser scanner. In the first section the laser scanner is presented; the scanning system is able to scan, in a reliable way, in an uncontrolled environment and characterized by an open and modular architecture; both HW and SW, has been fully and internally developed. The focus is shifted from the components and the technological processes to the power of the calculus; taking into account the progresses obtained nowadays in this field. An innovative methodology of calibration has been developed; it is based on a non-parametric approach that maps the entire working volume of the scanner, regardless the differences between the theoretical model and the real object. This methodology is really competitive since it avoid any type of error of the system, allowing to be independent from the quality of the assembling and the components used. The drawback is that it requires the management of a huge quantity of data, which is nowadays possible with the new commercially available computers. In the second section the integration of the industrial robot with the laser scanner is analyzed. The robot have to manipulate the scanner in order to cover all parts of the target object within the manipulator workspace; normally each sensor position is described through an individual and local coordinate system, an innovative calibration routine was developed to allow transformation of all the data collected in a global and unique coordinate system. In the third section the preparation of the data for 6-axis computer numerically controlled machining is presented. Robot programs are generated off-line from a CAD model obtained with the datasets acquired by laser scanner. The system becomes fully autonomous and capable of dealing with small production series without human intervention for reprogramming and adjustments. In the last section experimental results showed the solution flexibility. For example, the 3D data is being used by artists in their work and as a tool to realize their ideas. The artist can create sculptures one tenth of the size of the final sculptures and employ the milling system for realize a small batch production of their works of art.