Abstract：According to 3D geometric characters of ranged gaps on freeform shape, a novel rapid dimensional measuring system integrating laser scanning technologies and virtual measuring environments was developed. Based on the geometric information of acquired feature points of measured gap, the view angle and scanning depth of laser scanner can be determined step by step, thus automated generating an effective sampling path. Then, the positions of feature points have been identified and located by the respect of their absolute difference in the finding direction. In the global coordinate, the shape of measured ranged gaps was constructed by critical feature points set based on non-linear least-square method and the geometric dimensional can be also real-time obtained. The experiments on special gap artifact (200 mm×50 mm×32 mm) with freeform curve and multi-scale features were carried out to determine the accuracy and reliability of measuring system, the experimental results indicate that the dimension of gap artifact, including width, depth and flush, were perfectly measured in only 60s with the resolution less than 0.005mm and the measuring precision over 0.025mm. According to the actual operation results, the proposed measuring system is characterized by high automation and high efficiency, and can be well acceptable for application as online dimensional inspection for range gap on freeform shape on the automobile or aerospace production line.
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2018, Vol. 39 
