Design of an expert manufacturing system for a plug type job

Abstract

The manufacturing systems of the future will possibly be radically different from the present day conventional ones: NC, FMS, CIM, MAP etc. will be common terminologies in the future plants. This development phenomenon will have its consequential influence on the production systems of the developing countries, which depend to a large extent on the hardwares of the developed countries. At the same time the manufacturing sectors of the developing countries are facing a further threat from those of the developed, the NICs and the petro-dollar countries; thus the developing countries are losing th~ir knowledge containers (viz. shop supervisor, production planners etc.), which need a long lead time for generation. Expert Manufacturing System (EMS) is being' proposed to help the developing countries (like Bangladesh) out of this problem. The model of an EMS is being proposed to take account of this structural change in hardware and humanware technologies. The EMS consists of mainly three parts 1.e. 1) Knowledge Base, 2) Inference Engine and 3) User interface. The knowledge base of an expert system contains both declarative and procedural knowledge. The procedural knowledge is represented by rules. For declarative knowledge two data bases namely static data bases and dynamic data bases are used. The inference engine is the control and, inference strategy of the system. For inference strategy modus ponens is used and for control strategy branching method is used. The reasoning are governed here by forward chaining. The user interface component enables the user to communicate with an expert system. For the development of the system it is assumed that the job is to be a plug type job with three external surfaces and the sy.stem is capable of selecting blank, fixtures and identifying required operations and their sequences. A suitable one is selected among the available blanks on the basis of minimum material removal. The operat ions identification is done on the basis of logical sequence of operations. The selection of fixtures is done on the basis of minimum job deflection; here only some job holding and extra supporting devices of a conventional machine tool such as lathe is considered. To develop EMS, PROLOG is used for programming and it runs on an IBM PC with an MS DOS operating system. To implement the EMS, no special computer knowledge is necessary, only some physical job characteristic should be inputed into the system through man-machine interaction. The results obtained by EMS is more logical and the interaction procedure is friendly.