Application of Fuzzy Set Theory to Setup Planning

Summary Computer-aided process planning and computer-aided fixture planning have been widely researched in the last two decades. Most of these computer-aided systems are, however, either dealing only with process planning or fixture design. This paper advocates set-up planning as a link between these two functions. A set-up planning system for the machining of prismatic parts on a 3-axis vertical machining centre is proposed. This system formulates set-up plans based on the initial, intermediate and final states of a part. The system uses the fuzzy set representation, along with production rules and object representation. This hybrid representation scheme aptly depicts the inexact relationships among features required on a final part, and with those currently present on the part These inexact relationships, which greatly affect set-up planning, are manifestations of the various process and fixture planning constraints in the system. The consideration of these features' relationships together with the intermediate states of a part, allow the system to plan forward without the need to backtrack. Through this representation, the set-up planning problem is formulated using the fuzzy set theory. Using this approach, the proposed system is able to generate set-ups that fulfil the process and fixture planning requirements that are commonly practised by experienced planners.