Geometric reasoning for re-allocation of supporting and clamping positions in the automated fixture design system

Geometric reasoning is an indispensable part of an automated fixture design system. This paper introduces a rational approach based on the use of both qualitative and quantitative reasoning tools to plan for the "best" supporting, locating and clamping positions (on a given workpiece) to hold the workpiece rigidly and accurately during machining processes. It discusses general algorithms to verify the preliminary fixture configuration, as obtained by using 3-2-1 locating rules against workpiece deformation and workpiece-tool interference, and to re-allocate the locating positions, if necessary. The paper also addresses the issues of implementing the algorithm in a prototype, automated fixture design system.