An efficient algorithm for computing object poses in a modular fixture or gripper

Modular or reconfigurable fixtures (or grippers) can reduce manufacturing costs and time remarkably. Computing the poses of a given object in a modular fixture is a basic but tedious technique for designing and using such fixtures. This article presents an efficient algorithm for computing the poses. Starting from a unified expression of the outline of an object, this algorithm searches all matching poses automatically. If the outline consists of straight lines and circular arcs only, all the unknown variables can be calculated sequentially by substituting known (or tentative) data in respective expressions, without solving complicated simultaneous equations. When applied to arbitrary outlines, it involves nothing more than common interpolation. The search process is visualized through diagrams that clearly display the occurrence of matching poses. The computer programs are universally applicable. Only the data of the object outline and the fixture configuration need be input. Case studies show that the programs run fast and yield accurate results.