Selection of preliminary locating and clamping positions on a workpiece for an automatic fixture design system

This paper focuses on the development of heuristic algorithms for selecting the locating and clamping positions on an automatic fixture configuration for a given workpiece for an automatic fixture design (AFD) system. It discusses several issues regarding (i) an informationally complete product model, and (ii) the development of necessary computational modules coupled with a knowledge based system to reason about the workpiece's geometric characteristics for determining the locating and clamping positions. The motivation of the work is to develop a fixturing subsystem as an integral part of the complete CIM environment. A prototype AFD system has been completed in the object oriented programming platform of Wisdom's Concept Modeller. It has used several geometric reasoning mechanisms based on the traditional fixture design principles, and on the principles of collision-free assembly. The system exploits the power of Wisdom's advanced geometric modelling (AGM), and it implements the basic architecture of the proposed knowledge based fixture design system.