Flexible Manufacturing Facility Research Articles

The Case for Condition Based Maintenance

The introduction of ever more complicated machinery and associated operating procedures is placing an increasing strain on the maintenance function. The options available to a company engaged in the manufacture of a range of sheet metal products, for which a flexible manufacturing facility has been installed, are examined. The introduction of this system has caused the company to examine its maintenance procedures, which are based on a traditional breakdown and repair approach, and has prompted an investigation into the possibility of implementing a condition based approach to maintenance. This investigation is presented here, together with a review of currently available options, and an outline of the planned move towards condition based maintenance.

Synthesis of feedback control logic for a class of controlled Petri nets

An efficient solution is developed for a class of forbidden state problems for discrete event systems (DESs). DESs are considered which can be modeled as cyclic controlled marked graphs (CMGs), a special class of controlled Petri nets (CPNs). The distributed representation of the DES state in terms of the CMG marking permits an efficient specification of the forbidden states in terms of individual place markings. More important, it is shown that the graphical representations of the state transition logic in a CMG can be used to synthesize state feedback logic which is maximally permissive while guaranteeing the forbidden states will not occur. The practical application of the theoretical results is illustrated for an example of automated guided vehicle (AGV) coordination in a flexible manufacturing facility. >

Analysis of flexibility with rationing for a mix of manufacturing facilities

A major competitive advantage of a flexible manufacturing facility is its ability to cope with uncertainties in demand. At a strategic level, capacity-size decisions for a mix of flexible facilities (each not necessarily producing the same combination of products) are made based on aggregates of product types. Such an approach overlooks possible capacity-devouring by some products, arising at the operational level, when the aggregate demand for the period exceeds the available capacity. A rationing policy is required to ensure that the available aggregate capacity of the facilities is shared equitably. In this article, it is shown that such a rationing policy has an impact on the required capacity size and, therefore, must be integrated with the decisions at the strategic level. Several properties indicating the relative preferences of certain facility strategies are also established.

A Flexible Manufacturing Workstation

The flexible manufacturing facilities for current and future products must meet demanding productivity objectives and still be highly responsive to changeable customer needs. One method used to accomplish the productivity goals in manufacturing is to develop an open hardware and software architecture for production workstations. We describe a flexible workstation that provides specific capabilities in a broad spectrum of manufacturing applications, while conforming to the open architecture standards established within AT&T.