OMEGA: An Expert CAPP System

Author(s):  
Laurent Sabourin ◽  
François Villeneuve

Abstract This article presents the validation of a part analysis method for the creation of a process planning system for automobile prototype activity at the PSA group. The methodology presented is founded upon the division of the problem into two semi-separate sub-fields. The first consists in automatically defining the operation sequences, by the association between functional and machining features. The second one defines the sequencing of machining operations in set ups, founded upon a constraint planning strategy. The methods developed in this article have been implemented as an expert system named OMEGA.

Author(s):  
Sungdo Ha ◽  
Inshik Hwang ◽  
Myon Woong Park ◽  
Hyung-Min Rho

Abstract FAPPS (Feature-based Automatic Process Planning System) is developed as a comprehensive metal cutting process planning system operated in PC environments. It can recognize the machining features automatically from a given 3D part design model, and then generates operation sheets, divided process drawings, NC codes, and inspection sheet. It consists of the following modules: tolerance input module for menu-driven input of tolerances, feature recognition module for automatic recognition of pre-defined machining features and compound features, process planning module for rule based determination of machining processes, divided process drawing module for automatic generation of divided process drawings, operation planning module for rule based generation of specific operation plans, and measurement planning module for automatic generation of CMM measurement plans. The CMM measurement planning in FAPPS uses both geometric information and tolerance information from CAD files in order to determine measurement surfaces, number and positions of measurement points, and measurement sequences for inspecting machined parts. The measurement plan is represented in DMIS format for automated measurements using CMM’s. The measurement planning module that is realized in FAPPS is explained in this paper with the developed algorithms. Fuzzy logic calculation is used to determine the number of measurement points and geometric consideration for selecting measurement positions is performed.


Author(s):  
Hao Yang ◽  
Wen F. Lu

Abstract An intelligent case-based process planning system with interactive graphic simulation environment, PROCASE, is developed to demonstrate an integrated methodology of case-based process planning system. In PROCASE, both the mechanical part features and the machining operations are represented with a frame based scheme. PROCASE contains a retriever, a modifier, a simulator and a repairer. It distinguishes itself from traditional rule-based process planning systems by representing the process planning knowledge through previous process planning cases instead of production rules. It therefore can overcome some problems in the traditional rule-based expert systems. PROCASE currently resides in IRIS Indigo workstation. With a user friendly graphic environment, the generated process plans can be demonstrated vividly. This simulation environment not only serves as a good assistance in debugging, but also helps the user to be convinced of the outcomes of the reasoning of PROCASE.


Author(s):  
Taishi Hirai ◽  
Isamu Nishida ◽  
Ryuta Sato ◽  
Keiichi Shirase

In this study, we propose a new process planning system for machining operations, one which considers user strategies and intentions for such operations. In previous process planning systems, the machining sequence is calculated geometrically, based on the Total Removal Volume (TRV) and the machining primitive region split from TRV. However, it remains difficult to determine the best machining sequence from among the large number of machining sequences calculated. Also, previous process planning systems do not consider user strategies and intentions in determining the appropriate machining sequence. Our new approach stores geometrical properties of the machining primitives when the user selects a machining sequence. Using these stored geometrical properties, the appropriate machining sequence can be automatically selected. User strategies and intentions are thus considered in determining a machining sequence based on learned geometrical properties. A case study was conducted to show the effectiveness of our proposed process planning approach. In the case study, user-specific machining sequences were automatically determined for various users, based on the relation among the geometrical properties of the machining primitives and the individual user’s strategies and intentions.


Author(s):  
V. Sundararajan ◽  
Paul K. Wright

Agile methods of software development promote the use of flexible architectures that can be rapidly refactored and rebuilt as necessary for the project. In the mechanical engineering domain, software tends to be very complex and requires the integration of several modules that result from the efforts of large numbers of programmers over several years. Such software needs to be extensible, modular, and adaptable so that a variety of algorithms can be quickly tested and deployed. This paper presents an application of the unified process (UP) to the development of a research process planning system called CyberCut. UP is used to (1) analyze and critique early versions of CyberCut and (2) to guide current and future developments of the CyberCut system. CyberCut is an integrated process planning system that converts user designs to instructions for a computer numerical control (CNC) milling machine. The conversion process involves algorithms to perform tasks such as feature extraction, fixture planning, tool selection, and tool-path planning. The UP-driven approach to the development of CyberCut involves two phases. The inception phase outlines a clear but incomplete description of the user needs. The elaboration phase involves iterative design, development, and testing using short cycles. The software makes substantial use of design patterns to promote clean and well-defined separation between and within components to enable independent development and testing. The overall development of the software tool took about two months with five programmers. It was later possible to easily integrate or substitute new algorithms into the system so that programming resources were more productively used to develop new algorithms. The experience with UP shows that methodologies such as UP are important for engineering software development where research goals, technology, algorithms, and implementations show dramatic and frequent changes.


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