Automated inspection planning of free-form shape parts by laser scanning

The inspection operation accounts for a large portion of manufacturing lead time, and its importance in quality control cannot be overemphasized. In recent yeats, due to the development of laser technology, the accuracy of laser scanners has been improved significantly so that they can be used in a production environment. They are noncontact-type-measuring devices and usually have the scanning speed that is 50-100 times faster than that of coordinate measuring machines. This laser-scanning technology provides us a platform that enables us to perform a 100% inspection of complicated shape parts. This research proposes algorithms that lead to the automation of laser scanner-based inspection operations. The proposed algorithms consist of three steps: firstly, all possible accessible directions at each sampled point on a part surface are generated considering constraints existing in a laser scanning operation. The constraints include satisfying the view angle, the depth of view, checking interference with a part, and avoiding collision with the probe. Secondly, the number of scans and the most desired direction for each scan an calculated. Finally, the scan path that gives the minimum scan time is generated. The proposed algorithms are applied to sample parts and the results are discussed. (C) 2000 Elsevier Science Ltd. All rights reserved.