Multi-sensor blue LED and touch probe inspection system

Abstract

In dimensional metrology, contact and non-contact measurement methods each have their own respective strengths and weaknesses. Touch-trigger probes have low uncertainty, and perform well inside deep holes, but have a relatively slow data acquisition speed. By contrast, non-contact digitizers collect high density surface point clouds in seconds, and are much less likely to suffer from sensor collision with the part, but have a higher uncertainty than touch probes. In sheet metal forming, iterative design of the stamping die is needed due to the springback of the sheet metal part. Holes or other features of first article parts may be significantly out of tolerance, so the tactile measurement path created from the Computer Aided Design (CAD) nominal has to be adjusted to avoid cosine error. In more serious cases, probe collisions or missed touches may occur. When measuring holes in thin sheet metal, determination of the touch probe path height is also a challenge if the actual surface location differs from the nominal.To solve this problem and seize the complimentary advantages of contact and non-contact measurement methods, a multi-sensor blue Light Emitting Diode (LED) snapshot sensor and touch-trigger probe inspection system was developed, and affixed to a Coordinate Measuring Machine (CMM). The tactile measurement path was adjusted according to the approximate positions and sizes of the features obtained from the scanner iv data. The system includes an in-house designed calibration target for scanner calibration and a lightweight 2-axis rotary table for multiple-orientation scanning as well. Software in programming language C for interacting with the scanner and the CMM was developed.

A new method for registration of heterogeneous sensors in a dimensional measurement system

“…Mu et al [13] exploited a hexahedron for the registration of a trigger and arm laser scanner system. In [14], a target with two angled slots was conceived and manufactured to register data from a blue LED scanner and a touch probe by Xue et al Rak et al [15] also used material reference balls to calculate the transformation involving correction vectors between a laser scanner coordinate system and a contact probe coordinate system. Some adopted a two-step registration which consists of coarse and fine registration with coincident features [16,17], and others used an information fusion method [18].…”

On Development of Methods for Expressing Customer Affective Response for Apparel Products

“…The calibration algorithm is made up of the following steps performed on the CMM and the scanner data: plane fitting, plane-plane intersection, line projection and line-line intersection [43]. Plane fitting can have a non-unique solution, depending on the utilized method, and hence needs uncertainty estimation.…”