Juliana Keiko Sagawa

Modeling the dynamics of a multi-product manufacturing system: A real case application

In this paper, a continuous multi-product model is developed to represent the shop floor dynamics of a job shop, based on dynamic modeling and on analogies to electrical components. This approach allows the mathematical formulation of the model (state representation) and the analysis of its dynamic response via simulation. A real case application in the textile industry is presented. Thus, this research contributes in the following ways: first, proposing a model that is suitable for multi-product systems with intricate job shop configuration and that is generalizable to various manufacturing systems; second, presenting a real case application of the proposed model. As practical implications, it provides production managers and practitioners with a prescriptive decision model that considers the dynamics of the production systems and the interdependencies of the decisions made in the shop floor. From the academic perspective, it contributes to the existing literature by presenting the application of an alternative modeling methodology, and by extending this methodology to manufacturing systems with multiple products, instead of single-product systems. Continuous models such as the one proposed can benefit from a wide range of tools for system analysis and control design, come from control theory. Although these tools have been extensively applied to model the supply chain, applications devoted to the plant level seem to be neglected over the past years. This model also aims to contribute in this direction.

A closed-loop model of a multi-station and multi-product manufacturing system using bond graphs and hybrid controllers

Production plans and production schedules are fundamentally dynamic and may be disturbed by several events. In the manufacturing research domain, however, dynamic models for scheduling and production control usually receive less attention as static models. In this paper, a bond graph model for depicting a multi-product production system with job shop configuration is proposed. A case study based on a real production system is presented to illustrate the modeling process. The state model derived from the pictorial representation (i.e., derived from the bond graphs) is simulated, in order to observe the dynamic response of the system. Also, a hybrid proportional controller (HPC) and a hybrid adaptive proportional controller (HAPC) are proposed. In this sense, this research extends the findings of a previous work reported in the literature, in which constant and proportional controllers were tested. The results demonstrated that the HAPC and the HPC outperforms the mentioned controllers, and that the bond graphs are a viable methodology to represent and study the dynamics of manufacturing systems. This approach is innovative since no other closed-loop model based on bond graphs for multiple products has been previously reported in the literature, nor its combination with a hybrid adaptive controller.

Dynamic Models for Production Control and Scheduling: A Brief Review

Agility may be an important competitive advantage in many markets. In order to achieve it, the dynamics of the manufacturing systems must be considered. Control theory supports the development of dynamic models for production and inventory control. This paper discusses some dynamic models of production control specifically applied to scheduling and shop floor control. A comparative and critical analysis of the models is presented and directions for future works are provided.

Discussion of some Recent Empirical Research on Integration, Uncertainty and their Influence on Performance

Abstract As long as the production processes become more complex, specialized and geographically dispersed, the need for reintegrating functions and firms becomes stronger. Recently, several researchers have been investigating this topic. The uncertainty faced by the companies in their competitive environment must also be considered in this investigation, as a contingency variable. This paper reviews and discusses the empirical research that focus on integration, uncertainty and their relationships with firm performance. The different dimensions that form each construct are presented, and a conceptual framework to classify the reviewed studies is also proposed.