Agent technology has been considered as an important approach for developing distributed intelligent manufacturing systems. A number of researchers have attempted to apply agent technology to manufacturing enterprise integration, supply chain management, manufacturing planning, scheduling and control, materials handling, and holonic manufacturing systems. This paper gives a brief survey of some related projects in this area, and discusses some key issues in developing agent-based manufacturing systems such as agent technology for enterprise integration and supply chain management, agent encapsulation, system architectures, dynamic system reconfiguration, learning, design and manufacturability assessments, distributed dynamic scheduling, integration of planning and scheduling, concurrent scheduling and execution, factory control structures, potential tools and standards for developing agent-based manufacturing systems. An extensive annotated bibliography is provided.

Agent-Based Systems for Intelligent Manufacturing: A State-of-the-Art Survey

The emerging paradigm of agent-based computation has revolutionized the building of intelligent and decentralized systems. The new technologies met well the requirements in all domains of manufacturing where problems of uncertainty and temporal dynamics, information sharing and distributed operation, or coordination and cooperation of autonomous entities had to be tackled. In the paper software agents and multi-agent systems are introduced and through a comprehensive survey, their potential manufacturing applications are outlined. Special emphasis is laid on methodological issues and deployed industrial systems. After discussing open issues and strategic research directions, we conclude that the evolution of agent technologies and manufacturing will probably proceed hand in hand. The former can receive real challenges from the latter, which, in turn, will have more and more benefits in applying agent technologies, presumably together with well-established or emerging approaches of other disciplines.

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Agent-based systems for manufacturing

An enhanced text entry system using word-level analysis to automatically correct inaccuracies in user keystroke entries on reduced keyboards. The keyboard (105) may be a part of a touch-sensitive panel or display screen (100) or on a mechanical keyboard system. A method and system are defined which determine one or more alternative textual interpretations of each sequence of inputs detected within a designated auto-correcting keyboard region (106). The actual contact locations for the keystrokes may occur outside the boundaries of the specific keyboard key regions, where the distance from each contact location to each corresponding intended character may in general increase with the expected frequency of the intended word in the language or in a particular context. The user can easily select the intended word from among the generated interpretations.

Keyboard system with automatic correction

Applications of agent-based systems in intelligent manufacturing: An updated review ☆

There is disclosed an enhanced text entry system which uses word-level analysis to correct inaccuracies automatically in user keystroke entries on reduced-size or virtual keyboards. A method and system are defined which determine one or more alternate textual interpretations of each sequence of inputs detected within a designated auto-correcting region. The actual interaction locations for the keystrokes may occur outside the boundaries of the specific keyboard key regions associated with the actual characters of the word interpretations proposed or offered for selection, where the distance from each interaction location to each corresponding intended character may in general increase with the expected frequency of the intended word in the language or in a particular context. Likewise, in a virtual keyboard system, the keys actuated may differ from the keys actually associated with the letters of the word interpretations. Each such sequence corresponds to a complete word, and the user can easily select the intended word from among the generated interpretations. Additionally, when the system cannot identify a sufficient number of likely word interpretation candidates of the same length as the input sequence, candidates are identified whose initial letters correspond to a likely interpretation of the input sequence.

Virtual keyboard system with automatic correction

The proposed scheduling strategy is based on a multi-agent architecture. Each agent of this architecture is dedicated to a work centre (i.e. a set of resources of the manufacturing system); it selects locally and dynamically the most suitable dispatching rules. Depending on local and global considerations, a new selection is carried out each time a predefined event occurs (for example, a machine becomes available, or a machine breaks down). The selection depends on: (1) primary and secondary performance objectives, (2) the operating conditions, and (3) an analysis of the system state, which aims to detect particular symptoms from the values of certain system variables. We explain how the scheduling strategy is shared out between agents, how each agent performs a local dynamic scheduling by selecting an adequate dispatching rule, and how agents can coordinate their actions to perform a global dynamic scheduling of the manufacturing system. Each agent can be implemented through object-oriented formalisms. The selection method is improved through the optimization of the numerical thresholds used in the detection of symptoms. This approach is compared with the use of SPT, SIX, MOD, CEXSPT and CR/SPT on a jobshop problem, already used in other research works. The results indicate significant improvements.

Using multi-agent architecture in FMS for dynamic scheduling

The scheduling strategy proposed is based on a dynamic selection of certain pre-determined dispatching rules. A new selection is carried out each time a machine becomes available, depending on: (1) primary and secondary performance objectives, (2) operating conditions, (3) an analysis of the system state, which aims at detecting particular symptoms from the numerical values taken by state variables. This selection method is improved through the optimization of the numerical thresholds used in the detection of symptoms. A simple heuristic dispatching strategy, called 'shift from standard rules' (SFSR), has been designed based on this dynamic selection approach. It is compared to SPT, SIx, COVERT, CEXSPT, and CR/SPT on a job shop problem, already used in other research works. The results indicate significant improvements on the mean tardiness and the conditional mean tardiness. Moreover, this new approach allows several performance criteria, such as the mean flowtime and the mean tardiness, to be taken into...

Dynamic scheduling selection of dispatching rules for manufacturing system

Cell formation with alternative process plans and machine capacity constraints: A new combined approach

This paper describes a methodology for the choice of a pull production-control strategy. The methodology is based on optimization, using an Evolutionary Algorithm and discrete-event simulation, of a generic system that can model Kanban, Conwip, and Hybrid. This approach is illustrated through the examples of production lines with six, eight, and ten stages. The optimization procedure leads to a simplified Hybrid system.

An evolutionary approach to select a pull system among Kanban, Conwip and Hybrid

This paper is concerned with an optimization method for manufacturing systems. This method can be applied to optimize problems with any type of variables (variables from a real set, e.g., conveyor speed; an integer set, e.g., size of buffer; or any general set, e.g., dispatching rules). It is based on the association of an evolutionary algorithm and a simulation model. Extensions of Michalewicz's evolutionary operators and algorithm are proposed to tackle manufacturing system problems. The particular case of stochastic models is discussed. This method is applied to an example: the configuration of a workshop producing plastic yoghurt pots. The criterion to optimize is the cost of the workshop and the three variables are the size of a silo, the size of a warehouse and a choice between two manufacturing methods. The application has been realized by connecting an evolutionary algorithm programmed in C and a simulation language.

Henri Pierreval

Papers

Using multi-agent architecture in FMS for dynamic scheduling

Dynamic scheduling selection of dispatching rules for manufacturing system

Cell formation with alternative process plans and machine capacity constraints: A new combined approach

An evolutionary approach to select a pull system among Kanban, Conwip and Hybrid

Using evolutionary algorithms and simulation for the optimization of manufacturing systems