Shop Floor Control Software Research Articles

An e-releaser of production orders in the extended enterprise

This study has the objective to apply new Information and Communication Technologies (ICT) and multi-agent modelling concepts in order to support the business process of production orders release in extended/virtual enterprises. In a previous publication (Tatsiopoulos, Computers in Industry, 33, 335–344, 1997) an object-oriented orders release reference model has been defined as a link between production management and shop floor control software in the one-firm environment. This study's main objective is to extend this model in the multifirm extended enterprise, taking advantage of agent technology and the internet. The proposed solution is an integrated application called e-releaser, which is responsible for the order release process management in three different levels, these being the partner selection and order management, the material management and the capacity management level. Each one of these three sub processes is supported and managed by an agent based submodule of the e-releaser tool. Finally, the e-releaser application was field-tested in an industrial user of the apparel sector and gave rather satisfactory results in improving predefined business performance indicators such as process lead-time, process cost and cost per order.

Performance Modelling and Evaluation of Dynamic Tool Allocation in Flexible Manufacturing Systems using Coloured Petri Nets: An Object-Oriented Approach

Manufacturing systems are faced with ever-increasing customisation and unstable demand. The traditional hierarchical control structures for shop floor (pre-release planning, scheduling, dispatching and activity control) are often inflexible in responding to unexpected scenario changes and are thus not robust to system disturbances. In this paper, an object-oriented approach to modelling of FMS dynamic tool allocation and control under a non-hierarchical shop floor control scheme using coloured Petri nets is presented. A client-server paradigm is used in the proposed modelling method. The complete FMS model is partitioned into individual classes (machines, magazines, tool transport system, SGVs, tool storage, etc.) thereby significantly reducing the complexity of the model to a tractable size. The system performance under different tool request selection rules is also evaluated using coloured Petri net simulation. The proposed method can provide the designer of a tool management system with a high-level and structured representation of the tool-sharing control. It also provides an effective method for prototyping and evaluating performance of object-oriented shop floor control software.

Integrated framework of IDEF modelling methods for structured design of shop floor control systems

The information architecture for a shop floor controller provides the accurate and relevant data in an appropriate format. The information architecture is built by specifying the information requirements and by defining the information handling mechanism. The objective of the paper is to capture and specify the information requirements of workstation and machine controllers for hierarchical shop floor control in a discrete part manufacturing system. The information contents managed by the workstation and machine controllers are identified through IDEF0 function modelling activities. The IDEF0 function modelling method is used in order to guarantee the complete capture of the required information contents. Once being captured through inputs, outputs, controls and mechanisms of the function model, they are classified into two categories: Message and stored data. The flow models and specifications of the identified messages are presented using a variant IDEF3 process modelling method. Since the sequence of the messages does not appropriately appear on the function model, a dynamic message flow model is needed which describes message flows among controllers and functional modules. The captured data and their semantic relationships are modelled using the IDEF1X data modelling method. In particular, the evolution of planning and scheduling data is also identified and modelled as part of the information requirements. The specified information requirements show an integrated view of context of a SFCS, increase the understanding of functionality of a SFCS, and provide the stable basis for the SFCS development. The approach suggested in this paper can avoid the fatal errors in terms of information management in operating shop floor control software.

Modular control system with intelligent scheduling

A modular control system of a flexible manufacturing cell based on microcomputers and local area network is presented. Decentralisation and modularisation as architectural strengths of advanced Shop Floor Control-software (SFC) are emphasised. The system implementation with corresponding control modules is described. An expert routing and scheduling system using rule-based simulation is presented. The use of simulation module tightly connected to the manufacturing process to increase the system throughput is suggested.

Issues on the architecture of an integrated general-purpose ShopFloor control software system

The software necessary to carry out integrated control over individual shopfloor components has not been commercially available up to the present. Although some subjects of shopfloor control (SFC), such as production scheduling and shopfloor monitoring, have been extensively studied and matured solutions are now available. Rapid generation of SFC software for integrated control of shopfloors remains a challenge. In this paper, the design principles of an integrated software framework for SFC, for the purpose of facilitating integration and implementation of SFC for any specific shopfloor manufacturing system, is discussed. Keys to our integrated software framework are the use of open architecture; the creation of ontology for shopfloor and the normalisation of shopfloor control activities; and the application of agent concept and a hybrid control architecture.

Petri net models for message manipulation and event monitoring in an FMS cell

A shop floor control system (SFCS), the central part of a computer integrated manufacturing system, performs the production activities required to fill orders received from the factory level control system. In order to effectively control these activities, a hierarchically decomposed SFCS (equipment, workstation, and shop) can be devised and implemented. The controller at each level is functionally decomposed into planner, scheduler, and executor which perform various tasks such as part dispatching, resource selection and assignment, message passing, event monitoring, communication, machine code downloading, etc. In particular, the executor is responsible for (1) monitoring and interpreting input messages, (2) making execution-based decisions, and (3) broadcasting messages and downloading machine instruction. The purpose of the paper is to present the interpreted Petri net models of the executors embedded in the workstation and equipment level controller. Each event is captured and processed and then some actions associated with the event are taken. These series of activities are modelled using interpreted Petri nets in which a circle node represents the set of actions (e.g. message sending, state variables and database updating, etc.), a bar node represents an event (e.g. message capturing), and an edge represents the transition between two nodes. The execution models have been implemented in an FMS cell with dumb planner and schedulers (meaning that planning and scheduling prblems are randomly solved). The form description of the executors presented in this paper will provide the shop floor control engineer with the basis of the rapid generation of shop floor control software. Since the Petri nets detect and process all the events, including even planning and scheduling events, an FMS cell can be intelligently controlled by plugging in a planner and scheduler into the Petri net models.

An Orders Release reference model as a link between production management and shop floor control software

This paper presents a data-oriented reference model for the Orders Release process that forms the link between the production planning system and the production execution system. The terms planning system and execution system are recursively meant at all levels of the ISO manufacturing model (enterprise-factory-cell-work centre). A Releaser generic architecture is described in the form of a module structure that includes an Order Manager, a Material Manager and a Capacity Manager. The architecture is further decomposed into a data model layer and a function layer building a reference model with generic, partial and particular views. Those views are based on a production systems typology and the analysis of the influence of the typological characteristics on the Orders Release process.

Design principles for open and reusable shop-floor control software

Integrating a heterogeneous manufacturing environment means using information technology to provide appropriate access to accurate and timely information. While individual systems provide valuable solutions to particular manufacturing or transport problems, quick and easy information-sharing throughout the shop-floor has become almost impossible. Yet, information-sharing is increasingly critical for the success of the company and its manufacturing goals. Whether data comes from a device or an application in the manufacturing environment, the critical success factor in shop-floor integration is the ability to turn data into useful information, to distribute it, and to share it regardless of application, device, hardware, operating system, and network used. Manufacturing environments are changing constantly and the technology surrounding and supporting them is often changing faster. Solving manufacturing problems by acquiring a variety of incompatible hardware and software from multiple vendors has created a complex application and device integration problem. This paper describes an approach that makes the task of application integration easier. The concept focuses on achieving application independence and was verified in an assembly cell at a truck component factory.

A survey of priority rule-based scheduling

In this paper, we survey the literature on heuristic priority rule-based job shop scheduling. Priority rules have been intensively investigated over the last 30 years by means of simulation experiments. They are also used in Shop Floor Control software systems. We present a classification, a characterization, and an evaluation of elementary priority rules. Some priority rule-related model extensions are discussed.