In industrial manufacturing processes, the dimensional inspection of the gaps on the free-form shape parts is critical and challenging, and is directly associated with subsequent assembly and terminal product quality. In this paper, a fast measuring method for automated gap inspection based on laser scanning technologies is presented. The proposed measuring method consists of three steps: firstly, the relative position is determined according to the geometric feature of measuring gap, which considers constraints existing in a laser scanning operation. Secondly, in order to acquire a complete gap profile, a fast and effective scanning path is designed. Finally, the range dimension of the gaps on the free-form shape parts including width, depth and flush, correspondingly, is described in a virtual environment. In the future, an appliance machine based on the proposed method will be developed for the on-line dimensional inspection of gaps on the automobile or aerospace production line.
Non-contact measurement techniques using 3D laser scanning have the power to deliver tremendous benefits to most notably manufacturing, and have the advantage of high speed and high detail output. However, procedures for evaluation and verification of non-contact laser line scanner have not been well-established because of many influencing factors like scan depth, incident angle, probe head orientation and surface properties. A truncated pyramid artifact representation of five- planar with different included angles was designed and used to straightforwardly identify the influence of in-plane and out-of-plane angle, as well as scan depth on dimensional measurement accuracy of the laser scanner. Then, a series of easy, fast and representative experiments, based on this simple artifact, were performed on a commercial laser line scanner, and found that the output of this scanner can be improved for metrology applications after calibration.
Non-contact measurement techniques using laser scanning have the power to deliver tremendous benefits to most notably manufacturing, and have the advantage of high speed and high detail output. However, a major obstacle to their widespread adoption in more complex on-line producing environments is their geometric constraints and low accuracy compared to the contact-based counterparts. The work presented in this paper introduces a performance evaluation test of laser line scanning for in-process inspection of 3D geometries. Some straightforward test methods that use a designed artifact are proposed. First, one work aims to experimentally investigate the location accuracy of knee point or corner point of edge features using a commercial laser stripe scanner, which is common in mechanical parts. Another work experimentally investigates the formation of outliers that may be usually promoted by reflective surfaces around surrounding area of corner point, and these outliers are characterized with large measurement errors, which significantly deteriorate the quality of the scanned point cloud data. Scanning path planning and outlier filter design are respectively discussed.