Thierry Berger

A stigmergic approach for dynamic routing of active products in FMS

This paper illustrates the capacity of a stigmergic routing control model to automatically find efficient routing paths for active products in flexible manufacturing systems (FMSs) undergoing perturbations. The proposed model is based upon a functional architecture with two levels: a virtual level in which virtual active products (VAPs) evolve stochastically in accelerated time, and a physical level in which physical active products (PAPs) evolve deterministically in real-time. The physical active products follow the best paths that have been detected on the virtual level, with a virtual level exploration being triggered when a perturbation is diagnosed in the transportation system. The data used for the simulation on the virtual level is then updated to reflect the real state of the transportation system. The models adaptive capabilities are illustrated with several simulation scenarios using NetLogo software, and an on-going real implementation is presented.

ORCA-FMS: a dynamic architecture for the optimized and reactive control of flexible manufacturing scheduling

Abstract Reactive and effective hybrid manufacturing control architectures, combining hierarchy and heterarchy adapted to the current constraints of the industrial market and its environment were created. In this article, a new generic hybrid control architecture called ORCA (dynamic Architecture for an Optimized and Reactive Control) is first proposed. This hybrid architecture is able to dynamically and partially switch between a hierarchical predictive architecture and a heterarchical reactive architecture, if an event forbidding the planned behavior to be followed occurs. In this article, this architecture was applied to a Flexible Manufacturing System (FMS) problem and denoted ORCA-FMS. ORCA-FMS was tested on an existing manufacturing cell with simulations and real experiments to prove the applicability and the effectiveness of this kind of hybrid architecture in an industrial environment.

Reactive and energy-aware scheduling of flexible manufacturing systems using potential fields

This paper presents a reactive scheduling approach for flexible manufacturing systems, which integrates the overall energy consumption of the production. This work is justified by the growing needs of manufacturers for energy-aware control, due to new important environmental criteria, which holds true in the context of high reactivity. It makes production hard to predict. The proposed reactive scheduling model is based on potential fields. In this model, resources that sense the intentions from products are able to switch to standby mode to avoid useless energy consumption and emit fields to attract products. Simulations are provided, featuring three indicators: makespan, overall energy consumption and the number of resource switches. Real experiments were carried out to illustrate the feasibility of the approach on a real system and validate the simulation results.

The control of myopic behavior in semi-heterarchical production systems: A holonic framework

Heterarchical control architectures are essentially founded on cooperation and full local autonomy, resulting in high reactivity, no master/slave relationships and local information retention. Consequently, these architectures experience myopic decision-making, bringing entities towards local optimality rather than the systems overall performance. Although this issue has been identified as an important problem within heterarchical control architectures, it has not been formally studied. The aim of this paper is to identify the dimensions of myopic behavior and propose mechanisms to control this behavior. This study focuses on myopic behavior found in manufacturing control. For this particular study, we propose a holonic framework and a holonic organization that integrates specific mechanisms to control the temporal and social myopia. Our proposal was validated using simulations designed for solving the allocation problem in flexible manufacturing systems. These simulations were conducted to show the improvement by integrating the new mechanisms. These simulation results indicate that the myopic control mechanisms achieve better performance than the reactive strategies, because not only they introduce a planning horizon, but also because they balance local and global objectives, seeking a consensus.

Distributed manufacturing control with extended CNP interaction of intelligent products

This paper describes two heterarchical architectures which use distributed intelligence for the control (operation scheduling, resource allocation and product routing) of a manufacturing cell. In these architectures intelligence is put respectively at the product and through the network of workstation computers. The cost of embedded specialized hardware required for the first option is still very high. The second option needs the utilization of Automatic Identification and Data Capture technology close to the product to permit its identification and tracking by the computer system. These technologies enable the automated identification of objects, the collection of data about them, and the storage of that data directly into computer systems. Through this network, the computer system can access or update information in databases about the products and connect with software agents that represent production orders and resources and take in common decisions through negotiation and contract-based rules. The theory of the proposed solutions is based on the holonic manufacturing and product-driven automation concepts. The implementation methodology along with experimental results is presented, emphasizing the advantages of each solution.

Embedded holonic fault diagnosis of complex transportation systems

The use of electronic equipment and embedded computing technologies in modern complex transportation systems continues to grow in a highly competitive market, in which product maintainability and availability is vital. These technological advances also make fault diagnosis and maintenance interventions much more challenging, since these operations require a deep understanding of the entire system. This paper proposes a holonic cooperative fault diagnosis approach, along with a generic architecture, to increase the embedded diagnosis capabilities of complex transportation systems. This concept is applied to the fault diagnosis of door systems of a railway transportation system.

Semi-heterarchical control of FMS: From theory to application

This paper presents both a model and a real implementation of a semi-heterarchical control system for flexible manufacturing systems (FMS). After presenting the concepts of heterarchical and semi-heterarchical control, a product-based control structure, composed of a dynamic allocation process (DAP) and a dynamic routing process (DRP), is proposed. Though the associated control processes (DAP and DRP) are hierarchically dependant, each is managed heterarchically, with no supervisor. The dynamic allocation algorithms are presented, and our highly distributed approach to routing control is then explained in detail. A real distributed application of the active entities and the control architecture was implemented in the AIP-PRIMECA pole at the University of Valenciennes, and this implementation is described in detail. A mixed-integer linear model of the FMS was used to compute lower bounds. The flexibility and robustness of our approach are highlighted through several real experiments.

Role-based manufacturing control in a holonic multi-agent system

Multi-agent systems (MAS) are particularly adapted to deal with dynamic distributed environments and are typically used to manage business workflows or data flows in manufacturing systems. From a control perspective, holonic representation allows both the informational and the physical parts in such manufacturing systems to be modelled. In this article, we focus on the notion of role in holonic MAS (HoloMAS) and its contribution to the adaptive control of manufacturing systems. We validated our HoloMAS proposal using simulations and through a real implementation on a flexible assembly cell in our university lab. Our results clearly show that the notion of role helps to adapt and manage perturbations.

Semi-heterarchical Allocation and Routing Processes in FMS Control: A Stigmergic Approach

This paper deals with the production process control in flexible manufacturing systems (FMS), in which heterarchical relations exist between some decisional entities. After presenting a brief state-of-the art of the literature on the heterarchical concept we propose a semi-heterarchical control structure (composed of DAP: dynamic allocation process and of DRP: dynamic routing process), and explain the objective of our study. After presenting the concept of stigmergy, we focus in this paper on our innovative approach to routing in DRP including the active product concept. We then describe our two levels model and its main components (a virtual level VL in which virtual active products evolve stochastically in accelerated time, and a physical level PL in which physical active products evolve deterministically in real time). Our innovative approach exploits the capacity of a stigmergic routing control model to automatically find efficient routing paths for active products in FMS undergoing perturbations. After a brief presentation of the Netlogo simulation context, the qualitative and quantitative results are presented. The results illustrate the advantages of our routing approach and its capacity to surmount perturbations. The integration and implementation of our approach at the AIP-PRIMECA center in Valenciennes France is then detailed. Finally, we provide a brief overview of our future research concerning: firstly, a way to link our DRP model with the DAP distributed control system, secondly, the re-formulation of our model within the HMS (holonic manufacturing system) concept, and thirdly, the development of a new challenging and innovative concept of “hypervision”.

Switching mode control strategy in manufacturing execution systems

The paper describes a semi-heterarchical control solution for mixed planning and scheduling, routing and job execution in flexible manufacturing systems based on the paradigms of holonic manufacturing and product-driven automation. The main feature of the control solution is the bidirectional switching of the operating mode (scheduling, routing) between centralised and decentralised in the presence of perturbations to ensure as long as possible both global optimisation and agility to changes in batch orders, while featuring robustness to disturbances in the production environment. At the theoretical level, the control solution is described in terms of generic structural and dynamic models. The implementation is done using a multi-agent Java Agent Development Framework framework.