We propose an approach for integration of different levels of logistics and control in a uniform methodology. The main issue is that the formalisms we use on different levels allow fast and easy re-configuration at all levels, from business level down to shop floor control. The proposed technology promotes the plug & play concept and utilizes a similar formalism across all layers of an enterprise and between enterprises within a supply chain. Each plug & play component has embedded in it a controller which can be re-configured dynamically and automatically according to the rules and protocols defined at the upper layers of enterprise or the network it belongs to. Each component also embeds a monitoring system, which provides feedback on its status and if necessary can participate in a distributed diagnosis in the case of faults, drifts, and other disturbances. The paper presents the concepts we have been developing so far and addresses future work on integration of our approaches.

Modern manufacturing systems are highly automated and require distributed architectures in order to integrate enterprise-wide planning and decision making while providing scalability. In this paper, we introduce an architecture for scheduling and controlling a manufacturing system using distributed objects. We design a cell object, which encapsulates data and methods for scheduling and controlling the cell resources. New jobs entering the manufacturing system are allocated to cells based on schedules computed in real time by these distributed cell objects. We demonstrate the efficacy of this approach through empirical trials that compare it to scheduling and job dispatching using other methods.

There has been a great deal of interest in the application of fuzzy sets for representing uncertainty in management decision models. One of the important steps in the decision process is the elicitation of fuzzy judgments from the decision-makers. There are two elicitation procedures used in the existing literature: (1) direct numerical assessment and (2) linguistic variables. We introduce a third procedure, which we term the "fuzzy spatial instrument." We examine some characteristics of judgment elicitation procedures as measurement instruments. In particular, we conduct an empirical test of fuzzy measurement instruments using a set of subjects and evaluate the instruments on the criteria of reliability, validity, and imprecision. We conclude that the use of fuzzy instruments will introduce some level of imprecision into the decision-making process due to the nature of the instruments themselves.

A distinguishing feature of a flexible manufacturing system (FMS) is the ability to perform multiple tasks in one machine or workstation (alternative machining) and the ability to process parts according to more than one sequence of operations (alternative sequencing). In this paper, we address the issue of deadlock avoidance in systems having these characteristics. A deadlock-free and maximally permissive control policy that incorporates this flexibility is developed based on finite automata models of part process plans and the FMS. The resulting supervisory controller is used for dynamic evaluation of deadlock avoidance based on the remaining processing requirements of the parts.

One of the characteristics of flexible manufacturing systems (FMSs) is that they can consider multiple part routing due to alternate machining and alternate sequencing in the processing of parts. This paper presents a new architecture based on colored Petri nets (CPNs) that allows the supervisory controller of a flexible manufacturing cell to consider alternate machining and alternate sequencing in real time control of the cell. This capability for real time alternate routing is an extension of prior research on the application of CPN to modeling FMSs.