Searching Form-Closure Fixturing Points on Objects Described by Triangular Meshes

The paper deals with the problem of finding a form-closure fixturing of objects modeled with triangular meshes and considering as quality measure the maximum wrench that the object can resist in any direction. Although a triangular mesh is a polyhedral representation of the object, the number of faces is too large to allow a practical application of existing approaches for polyhedral objects, and therefore some search procedure have to be applied. In the proposed approach the search of contact points is done looking for points directly on the object boundary instead of on the wrench space. In this way, all the object surface is homogeneously considered, while the quality is evaluated in the wrench space. The procedure iteratively looks, using heuristic criteria, for sets of points that improve the quality. The procedure was implemented and some application examples are included in the paper to illustrate the performance.