Dynamic Reconfigurable Systems Research Articles

Prerouted FPGA Cores for Rapid System Construction in a Dynamic Reconfigurable System

This paper presents a method of constructing pre-routed FPGA cores. This lays the foundations for a rapid system construction framework. There are two major challenges that need to be considered by this framework. The first is how to manage the wires crossing a coreA¢â‚¬â„¢s borders. The second is how to maintain an acceptable level of flexibility for system construction with only a minimum of overhead. Typical FPGA based systems are built up from cores developed by multiple third parties. Each compilation step that a developer performs before delivery adds value in terms of a cores performance, predictability and readiness for purpose. The perceived advantages of full independent core development are weighed against the loss in placement flexibility and elimination of the opportunities to optimise a system across cores. Few existing methodologies allow the independent compilation of FPGA cores through every step of the design flow. The wire detail of modern FPGA architectures is captured in a model that is used to analyse how the interconnect architecture effects the shape of pre-routed cores and the wire bandwidth available to interfaces. We have adapted academic placement and routing algorithms to our architectural model. The design flow has been modified to include a wire policy and interface constraints framework that tightly constrains the use of the wires that cross a coreA¢â‚¬â„¢s boundaries. Using this tool set we investigate the effect of pre-routing on overall system optimality. Compiling a set of example systems using the pre-routed approach shows only a 2% increase in total wire use over the pre-placed approach. Place and route times are vastly reduced for systems composed of regular modules. Being able to break a system into independent cores reduces the placement and routing time even for non-regular systems, and will open opportunities for its possible use in resource constrained embedded systems.

Dynamic reconfiguration and simulation of manufacturing systems using agents

PurposeConventionally, various levels of decisions with regard to production are made in a number of sequential stages such as system design, production/process planning, production scheduling, system reconfiguration and system restructure. This paper aims to present an integrated approach for modelling, restructuring and simulating manufacturing systems to suit changing manufacturing situations as quickly as possible.Design/methodology/approachAn agent‐based approach is employed where each manufacturing resource is represented by an agent. Simply speaking, the approach enables the machines in a manufacturing system to manage themselves efficiently and effectively.FindingsThe agent‐based modelling and interaction approach enables manufacturing resources to be allocated dynamically in an optimal manner. The modelling approach also enables alternative system configurations to be identified and evaluated using distributed discrete event simulation system. Resource allocation and manufacturing system control can take place simultaneously with simulation.Originality/valueThis paper presents a successful integration of agent‐based modelling, process planning, scheduling, control, identification of alternative system configurations, simulation and analysis of the configurations and PLC reprogramming within a coherent framework for improved manufacturing responsiveness.

A hybrid algorithm based on particle swarm optimization and simulated annealing to holon task allocation for holonic manufacturing system

Manufacturing is currently undergoing a revolutionary transition with focus shifting from mass production to mass customization. This trend motivates a new generation of advanced manufacturing systems that can dynamically respond to customer orders and changing production environments. It is becoming increasingly important to develop control architectures that are reconfigurable and fault tolerant. A holonic manufacturing system (HMS) is a system of holons that can cooperate to achieve a common goal or objective. The holonic organization enables the construction of very complex systems that are efficient in the use of resources. This paper focuses on the dynamic re-configuration and task optimization of holonic manufacturing systems (HMS). The concept of dynamic virtual clustering is extended to the control process of a holarchy or holonic organization. A task-oriented clustering mechanism and a corresponding optimization algorithm are presented as an efficient approach to the holonic control in the HMS domain. The mediator-based dynamic virtual clustering mechanism is presented firstly. Then a negotiation strategy based on the contract net protocol is proposed for cooperative action among holons. Finally, a hybrid algorithm based on particle swarm optimization (PSO) and simulated annealing (SA) for holon task allocation is described to support the optimum organization of a holarchy. The hybrid algorithm combines the high speed of PSO with the powerful ability to avoid being trapped in local minimum of SA. Simulation results show that the proposed model and algorithm are effective.

A UAU test and development environment based on dynamic system reconfiguration

This paper describes ongoing research to develop a framework for implementing dynamically reconfiguring avionics and control systems for unmanned aerial vehicles (UAVs) and a test and development environment for experimental UAVs. The framework supports graceful degradation , where hardware and software failures cause a reduction in the quality or capability of the control system but does not result in total system failure. The approach uses a graphical specification representing modular software interdependencies and a runtime system manager that reconfigures the system. The techniques are currently being applied to the design of UAV control systems as part of the BIG BLUE Mars airplane testbed project at the University of Kentucky.

A reconfigurable platform in support of one-of-a-kind product development

In recent years, a variety of Internet-based systems has been developed for the purpose of Rapid One-of-a-Kind or customized Product Development (ROKPD). They can be applied in different stages of the product development process such as to rapidly capture customer requirements, and help produce high-quality products at low cost and short lead-time. Many of the systems, however, do not support rapid adaptation or dynamic reconfiguration of systems and tools for supporting ROKPD in a distributed manufacturing environment. To the authors’ knowledge, the infrastructure of such a reconfigurable platform for supporting distributed manufacturing has never been directly studied. This paper proposes an Internet-based reconfigurable ROKP platform that has been prototyped to serve as a substrate for integrating innovative tools and systems for One-of-a-Kind Production (OKP) companies in New Zealand. The main emphasis of this paper is to investigate how to build the Internet-based reconfigurable ROKPD platform and to design appropriate intelligent tools and systems for the purpose of rapidly and economically producing OKP products in the global environment. A number of recent developments are discussed, including the four open-domain infrastructure of the ROKPD platform, Internet-based data management systems, an integrated product data environment and a cost/lead time control tool.

An agent-based approach to reconfiguration of real-time distributed control systems

We describe a general approach for dynamic and intelligent reconfiguration of real-time distributed control systems that utilizes the IEC 61499 function block model. This work is central to the development of distributed intelligent control systems that are inherently adaptable and dynamically reconfigurable. The approach that is used takes advantage of distributed artificial intelligence at the planning and control levels to achieve significantly shorter up-front commissioning times as well as significantly more responsiveness to change. This approach is based on object-oriented and agent-based methods, and aims at overcoming the difficulties associated with managing real-time reconfiguration of an intelligent manufacturing system.

A graph based architectural (Re)configuration language

For several different reasons, such as changes in the business or technological environment, the configuration of a system may need to evolve during execution. Support for such evolution can be conceived in terms of a language for specifying the dynamic reconfiguration of systems. In this paper, continuing our work on the development of a formal platform for architectural design, we present a high-level language to describe architectures and for operating changes over a configuration (i.e., an architecture instance), such as adding, removing or substituting components or interconnectons. The language follows an imperative style and builds on a semantic domain established in previous work. Therein, we model architectures through categorical diagrams and dynamic reconfiguration through algebraic graph rewriting.

An open platform for reconfigurable control

Advances in software technology have the potential to revolutionize control system design. Component-based architectures encourage flexible "plug-and-play" extensibility and evolution of systems. Distributed object computing allows interoperation. Advances are being made to enable dynamic reconfiguration and evolution of systems while they are still running. Technologies are being developed to allow networked, embedded devices to connect to each other and self-organize. This article describes a software infrastructure that gives an open control platform (OCP) for complex systems that coordinates distributed interaction among diverse components and supports dynamic reconfiguration and customization of the components in real time. Its primary goals are to accommodate rapidly changing application requirements, incorporate new technology (such as hardware platforms or sensors), interoperate in heterogeneous environments, and maintain viability in unpredictable and changing environments. The next section describes the current practice in control system implementation and discusses features of a complex control system architecture. It is followed by a description of the desired features a software infrastructure must have to promote new advances in control system design. We then describe an open-control software infrastructure to support these desired features, followed by a brief overview of a first-generation prototype of this infrastructure that has been developed for an autonomous aerial vehicle control.

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

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.

Multiview access protocols for large-scale replication

The article proposes a scalable protocol for replication management in large-scale replicated systems. The protocol organizes sites and data replicas into a tree-structured, hierarchical cluster architecture. The basic idea of the protocol is to accomplish the complex task of updating replicated data with a very large number of replicas by a set of related but independently committed transactions. Each transaction is responsible for updating replicas in exactly one cluster and invoking additional transactions for member clusters. Primary copies (one from each cluster) are updated by a cross-cluster transaction. Then each cluster is independently updated by a separate transaction. This decoupled update propagation process results in possible multiple views of replicated data in a cluster. Compared to other replicated data management protocols, the proposed protocol has several unique advantages. First, thanks to a smaller number of replicas each transaction needs to atomically update in a cluster, the protocol significantly reduces the transaction abort rate, which tends to soar in large transactional systems. Second, the protocol improves user-level transaction response time as top-level update transactions are allowed to commit before all replicas have been updated. Third, read-only queries have the flexibility to see database views of different degrees of consistency and data currency. This ranges from global, most up to date, and consistent views, to local, consistent, but potentially old views, to local, nearest to users but potentially inconsistent views. Fourth, the protocol maintains its scalability by allowing dynamic system reconfiguration as it grows by splitting a cluster into two or more smaller ones. Fifth, autonomy of the clusters is preserved as no specific protocol is required to update replicas within the same cluster. Clusters are, therefore, free to use any valid replication or concurrency control protocols.