State space representation of manufacturing operation plans in the presence of flexible routing capability

Abstract

Manufacturing process planning in flexible manufacturing environments requires a highly efficient computerized representation, since the number of different alternatives grows rapidly as the level of flexibility of the manufacturing systems increases. Furthermore, in order to recommend a good manufacturing plan, it is necessary to be capable of generating all feasible alternatives. This paper describes a state space to represent manufacturing operation plans, which generates a compact representation of all possible manufacturing operation sequences and routes that can be applied to a certain part. The state space representation is a state transition graph in which the nodes represent the manufacturing operation states of the system, and the arcs the transitions between them. Such a representation forms the basis for efficient planning algorithms that enable the manufacturing system to select a course of action according to current factory conditions. Computational experiments demonstrate the effectiveness of the proposed representation.

A tree unification approach to constructing generic processes

“…We note that by following the definitions in binary tree representation, we relate nodes to operations and arcs operations precedence. In other modeling/representation tools pertaining to manufacturing/assembly processes, such as AND/OR graphs (Benjaafar and Ramakrishnan, 1996;Homem de Mello and Sanderson, 1990), directed acyclic graphs (Borenstein, 2000) and state transition graphs (Borenstein and Becker, 2004), nodes and arcs are defined in a similar way. In general, two types of nodes can be identified: l-nodes and i-nodes.…”

“…Following Zheng et al (2008), Borenstein and Becker (2004) and others, we have taken a product to relate to a single production process. However, we note that based on a generic process, multiple processes can be planned for a given product in the corresponding family.…”

Applying fuzzy rule based to flexible routing problem in a flexible manufacturing system

“…However, most of the existing literature dealing with routing flexibility has primarily been devoted to the push-type production systems. A state space was described to represent manufacturing operation plans, which generates a compact representation of all possible manufacturing operation sequences and routings that can be applied to a certain part [21]. Although extensive research has been conducted on design and operational problems of automated manufacturing systems, many problems remain unsolved.…”