Pierre Castagna

Using online simulation in Holonic manufacturing systems

This paper deals with the use of online simulation on Holonic manufacturing systems. Concepts needed for the use of online simulation in a classical hierarchical system were already defined, the observer being the central one. The behaviors differences between both classes of systems are studied to determine the best way to adapt these concepts to this new environment. In the product resource order staff approach (PROSA) reference architecture, staff holons were chosen to welcome the simulation models and the observer. An application on an industrial sized Holonic manufacturing system is described to demonstrate the validity of the approach.

Performance evaluation of In-Deep Class Storage for Flow-Rack AS/RS

This article presents a new storage-retrieval method called In-Deep Class Storage, designed for Flow-Rack AS/RS. Class-based storage is a well-known method that has an extensive literature; our method is based on the fact that it is more efficient to dedicate the front layers of each bin to the class of the most popular items rather than dedicating whole bins close to the drop-off station. Clearly, this idea is not trivial to implement due to the dynamic behaviour of such racks. Thus, two separate algorithms have been defined, one for storage and one for retrieval, enabling dynamic use of our approach, with the only hypothesis of a Pareto distribution of item demand. This article presents a simulation study designed to compare the performance of random storage and retrieval with the use of the algorithms. This study shows a significant improvement of the expected retrieval delay, the main performance indicator selected for the study.

A modeling framework for manufacturing services in Service-oriented Holonic Manufacturing Systems

Holonic and Service-Oriented Architectures have been proposed as solutions for the conception of flexible and reactive systems. The combination of both architectures has been recognized as an attractive solution for the conception of more flexible and reactive systems. Services, originally conceived for web applications, need new models that better adapt to the needs of manufacturing systems namely, the specification and planning of processes. This paper proposes a methodology for designing customizable product-process specifications based on manufacturing-services that are suitable for product driven applications. A framework is proposed for modeling manufacturing-services designed for its application in Holonic Manufacturing Systems, preserving the fractal character found in products and processes. Three types of manufacturing processes are identified based on the relations among its composing operations and a model is proposed for each type. Application service-ontologies are created to describe operations and resource capabilities rather than complex semantic descriptions to facilitate process design and reduce the computational load of service discovery for planning. The framework leverages service reusability among process families in the same way as physical features are reused among product families. An illustrative example describes the design of a products process specification based on the manufacturing service framework in a Holonic Manufacturing System, giving rise to Service-oriented Holonic Manufacturing Systems. A framework for designing Manufacturing Services (MServices) is proposed.Service-oriented Holonic paradigm fosters flexibility in manufacturing control.MServices is the main communication primitive in distributed control systems.Automatic discovery of process capabilities is made possible with MServices.SoHMS formalism enables plug and produce and reusability principles.

A Petri net-based methodology to increase flexibility in service-oriented holonic manufacturing systems

The way information is presented to the system limits the flexibility the holonic control system can achieve.Service-based process models adapt to the fractal structure of holonic architectures.Process models, based on application-specific and/or domain-specific service-ontologies, are independent of workshop knowledge.A Petri net service-oriented process model is proposed for integrated process planning and scheduling.A set of modeling rules is proposed for the automatic generation of the Petri net process model. Distributed control systems such as the holonic manufacturing systems and service-oriented architectures have demonstrated to provide higher levels of flexibility, notably in the planning and scheduling functionalities, if well exploited. In scheduling, the use of fixed process plans generated by traditional planning approaches, usually leads to unrealistic schedules due to the lack of considerations of the workshop status. IPPS approaches try to break the gap between these two functionalities in favor of providing flexible plans adapting to the shop floors state. A key element in the creation of flexible process plans is the definition of a process model capable of representing alternatives solutions to the sequencing problem and therefore increasing the potential solution space. This paper presents a methodology to increase planning flexibility in service-oriented manufacturing systems (SOHMS). The methodology introduces a Petri net service-oriented process model (SOP model) capable of computing a products deadlock free sequential space and adapts to the fractal character of holonic architectures. A set of modeling rules, with illustrations, is presented for the automatic generation of the Petri net, based on a set of precedence conditions. To explore the solution space represented by the SOP model a holonic interaction protocol is presented. Moreover, a set of behavioral strategies is proposed in order to cope with the effects of a possible combinatorial explosion. A study case applied workshop example is presented to illustrate the modeling process of SOP models, compute the sequential solution space and demonstrate how this notably increases the number of potentially goods feasible solutions.

Coupling predictive scheduling and reactive control in manufacturing hybrid control architectures: state of the art and future challenges

Nowadays, industrials are seeking for models and methods that are not only able to provide efficient overall production performance, but also for reactive systems facing a growing set of unpredicted events. One important research activity in that field focuses on holonic/multi-agent control systems that couple predictive/proactive and reactive mechanisms into agents/holons. Meanwhile, not enough attention is paid to the optimization of this coupling. The aim of this paper is to depict the main research challenges that are to be addressed before expecting a large industrial dissemination. Relying on an extensive review of the state of the art, three main challenges are highlighted: the estimation of the future performances of the system in reactive mode, the design of efficient switching strategies between predictive and reactive modes and the design of efficient synchronization mechanisms to switch back to predictive mode.

Conflict-free AGV routing in bi-directional network

This paper deals with the problem of conflict-free routing of a set of AGVs moving on a bi-directional guide-path. We propose a robust predictive method of routing without conflicts. Our approach consists of adding a layer of real time control to the method proposed by Kim et al.

Proactive production activity control by online simulation

In this paper, we present a new application of discrete–event simulation as a forecasting tool for the decision support of the production activity control of a complex manufacturing system. The specificity of such an application of simulation is the short term of the forecasts. This specificity implies that the initial state of the simulation takes into account the actual state of the system. The development on a real–size flexible manufacturing system shows the technical feasibility of the developed concepts and the potential benefits on the productivity of a single example.

H2CM: A holonic architecture for flexible hybrid control systems

Several studies typically arise from the interaction of discrete planning algorithms or control and continuous processes, normally called hybrid control systems. It consists in three distinct levels, the controller, the plant and the interface. Hybrid control systems are conventionally modeled by switching patterns using the whole system instead of atomic resource. Therefore, the reconfiguration process is complex because it must take into account the system as a whole, making the hybrid control systems inflexible and more susceptible to uncertainties. The need for flexibility thus leads several teams to investigate the application of holonic paradigm to hybrid control systems. The objective of this paper is to demonstrate the possibility to apply almost directly a holonic discrete-event based reference architecture to hybrid control systems. A case study of industrial electricity generation process was taken, specifically a combined cycle plant (CCP) for verifying the proper operation of the proposed architecture.

Product Specification for Flexible Workflow Orchestrations in Service Oriented Holonic Manufacturing Systems

Holonic Manufacturing Systems are a response solution for the emergent need of flexible, reactive and productive manufacturing systems. This paper relies on PROSA, a classical holonic reference architecture, which makes use of a product specification, a process specification and a means to determine a resource’s production abilities and capacity, but does not define a specific method for representing such. This paper proposes an approach to define a product’s process specification model that integrates the principles and advantages of Service-oriented Architectures, Petri-Nets and Product Families. Then, a re-definition of the basic holons is given to have a glimpse on a possible exploitation of this new approach, together with a short-term forecasting strategy, for the flexible orchestration of workflows. Finally, it is shown how the proposed product’s process specification model enhances the HMS’s flexibility, reactivity and productivity giving rise to a Service-oriented Holonic Manufacturing System.

Proposal of an Approach to Automate the Generation of a Transitic System's Observer and Decision Support using Model Driven Engineering

Abstract Short term decision support for manufacturing systems is generally difficult because of the initial data needed by the calculations. Previous works suggest the use of a discrete event observer in order to retrieve these data from a virtual copy of the workshop, as up to date as possible at any time. This proposal offered many perspectives, but suffers from the difficulties to generate a decision support tool combining decision calculations and observation. Meanwhile, interesting developments were made in literature about automatic generation of logic control programs for those same manufacturing systems, especially using the Model Driven Engineering. This paper suggests the use of Model Driven Engineering to generate logic control programs, the observer and the decision support tool at the same time, based on the same data collected by the designer of the system. Thus, the last section presents the evolution needed in the initial data structure, as well as the conception flow suggested to automatize the generation.