Multi-level localization method for free-form surface

Aimed at the difficulty in getting the corresponding points in free-form surface localization of workpiece, a two-level localization method is presented. Firstly, some points distributed uniformly on workpiece surface and CAD surface are selected. Then the features are extracted and pairs of corresponding features are matched. The transformation is computed to achieve the pre-positioning and the accurate positioning. In this process, a probing strategy based on the optimization of the maximum eigenvalue is proposed to reduce the computing time. Results of a case study prove the validity of the presented method.