Introduction

Abstract

To provide a unified and fully systematic approach to the study and modeling of the generalized automatic production line (APL) is an almost impossible challenge. Indeed, each production line is most often a custom prototype devoted to a specific product. However, recently, emphasis has been placed on the design and definition of a number of generally applicable guidelines for production systems. The ever-growing complexity and, in consequence, the costs of production lines have stimulated the search for fabrication systems with more flexibility. By this concept, we mean the capability of using the same system to produce a family of products rather than just a single one. These flexibility requirements generate several new problems, both at the conception, and at the operating policy levels. In the crowded world of assorted devices, various prototypes, fancy tricks and black magic which has traditionally populated the field of automatic production systems, this additional flexibility requisite imposes the difficult task of identifying those existing devices capable of being adapted, and the building new machines able to work on families of objects. To progress towards this goal, it is necessary to fully understand and control the dynamical behaviours of APLs and ultimately attempt to partly bridge the gaps between the practical know-how and the theoretical research communities. It is obviously very difficult to formulate rigorously the manner in which this reflexion should be conducted. However, it is safe to draw analogies and consider any operating production line as an off-equilibrium thermodynamical system.