Combination of a vision system and a coordinate measuring machine for rapid coordinate metrology

This paper presents a novel methodology that integrates a vision system and a coordinate measuring machine for rapid coordinate metrology. Rapid acquisition of coordinate data from parts having tiny dimension, complex geometry and soft or fragile material has many applications. Typical examples include Large Scale Integrated circuit, glass or plastic part measurement, and reverse engineering in rapid product design and realization. In this paper, a novel approach to a measuring methodology for a vision integrated coordinate measuring system is developed and demonstrated. The vision coordinate measuring system is characterized by an integrated use of a high precision coordinate measuring machine (CMM), a vision system, advanced computational software, and the associated electronics. The vision system includes a charge-coupled device (CCD) camera, a self-adapt brightness power, and a graphics workstation with an image processing board. The vision system along with intelligent feature recognition and auto-focus algorithms provides the feature point space coordinate of global part profile after the system has been calibrated. The measured data may be fitted to geometry element of part profile. The obtained results are subsequently used to compute parameters consist of curvature radius, distance, shape error and surface reconstruction. By integrating the vision system with the CMM, a highly automated, high speed, 3D coordinate acquisition system is developed. It has potential applications in a whole spectrum of manufacturing problems with a major impact on metrology, inspection, and reverse engineering.