Showing papers on "Control reconfiguration published in 2005"

Flexible and reconfigurable manufacturing systems paradigms

Abstract: Reconfigurable Manufacturing System (RMS) is a new manufacturing systems paradigm that aims at achieving cost-effective and rapid system changes, as needed and when needed, by incorporating principles of modularity, integrability, flexibility, scalability, convertibility, and diagnosability. RMS promises customized flexibility on demand in a short time, while Flexible Manufacturing Systems (FMSs) provides generalized flexibility designed for the anticipated variations and built-in a priori. The characteristics of the two paradigms are outlined and compared. The concept of manufacturing system life cycle is presented. The main types of flexibility in manufacturing systems are discussed and contrasted with the various reconfiguration aspects including hard (physical) and soft (logical) reconfiguration. The types of changeability and transformability of manufacturing systems, their components as well as factories, are presented along with their enablers and compared with flexibility and reconfigurability. The importance of having harmonized human-machine manufacturing systems is highlighted and the role of people in the various manufacturing paradigms and how this varies in pursuit of productivity are illustrated. Finally, the industrial and research challenges presented by these manufacturing paradigms are discussed.

Grid'5000: A Large Scale and Highly Reconfigurable Grid Experimental Testbed

Abstract: Large scale distributed systems like Grids are difficult to study only from theoretical models and simulators. Most Grids deployed at large scale are production platforms that are inappropriate research tools because of their limited reconfiguration, control and monitoring capabilities. In this paper, we present Grid'5000, a 5000 CPUs nation-wide infrastructure for research in Grid computing. Grid'5000 is designed to provide a scientific tool for computer scientists similar to the large-scale instruments used by physicists, astronomers and biologists. We describe the motivations, design, architecture, configuration examples of Grid'5000 and performance results for the reconfiguration subsystem.

Three Dimensional Stochastic Reconfiguration of Modular Robots

Abstract: Here we introduce one simulated and two physical three-dimensional stochastic modular robot systems, all capable of self-assembly and self-reconfiguration. We assume that individual units can only draw power when attached to the growing structure, and have no means of actuation. Instead they are subject to random motion induced by the surrounding medium when unattached. We present a simulation environment with a flexible scripting language that allows for parallel and serial selfassembly and self-reconfiguration processes. We explore factors that govern the rate of assembly and reconfiguration, and show that self-reconfiguration can be exploited to accelerate the assembly of a particular shape, as compared with static self-assembly. We then demonstrate the ability of two different physical three-dimensional stochastic modular robot systems to self-reconfigure in a fluid. The second physical implementation is only composed of technologies that could be scaled down to achieve stochastic self-assembly and self-reconfiguration at the microscale.

Formation Establishment and Reconfiguration Using Impulsive Control

Abstract: We analyze spacecraft formation establishment and reconfiguration problems for two-body orbits. The desired formations are characterized by nonsingular orbital-elemental differences. An analytical, two-impulse solution is proposed for achieving the desired orbital-elemental differences. Gauss's variational equations are used to compute the corresponding impulse magnitudes analytically and the resulting solutions can be easily implemented using onboard computational resources. It is also shown that the cost obtained from the analytical solution differs by less than 1 % from that obtained by numerical optimization.

Radio Frequency Identification (RFID) Network System and Method

Abstract: A bidirectional radio frequency identification (RFID) network system and method are presented. The system allows users to configure, monitor, and manage different sensor devices by using a graphical user interface real-time. The reconfiguration is done through a network management computer at the top system level that receives user input, generates code images according to the user input, and appropriately routes the code images to sensor routers that directly control the sensors. If the system is multi-layered, some code images are also sent to the intermediate-level network management computers. The system allows users to not only monitor a business flow but react to problematic situations quickly by adjusting the workflow. The aspect-oriented nature of the system allows users to reconfigure the system based only the Functionality aspects without worrying about the Partitioning aspects (e.g., how the network and the sensors are physically connected).

Path-based distribution network modeling: application to reconfiguration for loss reduction

Abstract: This paper is devoted to efficiently modeling the connectivity of distribution networks, which are structurally meshed but radially operated. A new approach, based on the "path-to-node" concept, is presented, allowing both topological and electrical constraints to be algebraically formulated before the actual radial configuration is determined. In order to illustrate the possibilities of the proposed framework, the problem of network reconfiguration for power loss reduction is considered. Two different optimization algorithms-one resorting to a genetic algorithm and the other solving a conventional mixed-integer linear problem-are fully developed. The validity and effectiveness of the path-based distribution network modeling are demonstrated on different test systems.

Main chain representation for evolutionary algorithms applied to distribution system reconfiguration

Abstract: Distribution system problems, such as planning, loss minimization, and energy restoration, usually involve network reconfiguration procedures. The determination of an optimal network configuration is, in general, a combinatorial optimization problem. Several Evolutionary Algorithms (EAs) have been proposed to deal with this complex problem. Encouraging results have been achieved by using such approaches. However, the running time may be very high or even prohibitive in applications of EAs to large-scale networks. This limitation may be critical for problems requiring online solutions. The performance obtained by EAs for network reconfiguration is drastically affected by the adopted computational tree representation. Inadequate representations may drastically reduce the algorithm performance. Thus, the employed representation for chromosome encoding and the corresponding operators are very important for the performance achieved. An efficient data structure for tree representation may significantly increase the performance of evolutionary-based approaches for network reconfiguration problems. The present paper proposes a tree encoding and two genetic operators to improve the EA performance for network reconfiguration problems. The corresponding EA approach was applied to reconfigure large-scale systems. The performance achieved suggests that the proposed methodology can provide an efficient alternative for reconfiguration problems.

Managing dynamic reconfiguration in component-based systems

Abstract: We propose a meta-framework called ‘Plastik' which i) supports the specification and creation of runtime component-framework-based software systems and ii) facilitates and manages the runtime reconfiguration of such systems while ensuring integrity across changes. The meta-framework is fundamentally an integration of an architecture description language (an extension of ACME/Armani) and a reflective component runtime (OpenCOM). Plastikgenerated component frameworks can be dynamically reconfigured either through programmed changes (which are foreseen at design time and specified at the ADL level); or through ad-hoc changes (which are unforeseen at design time but which are nevertheless constrained by invariants specified at the ADL level). We provide in the paper a case study that illustrates the operation and benefits of Plastik.

Apparatus, method, system and executable module for configuration and operation of adaptive integrated circuitry having fixed, application specific computational elements

Abstract: The present invention concerns configuration of a new category of integrated circuitry for adaptive computing. The various embodiments provide an executable information module for an adaptive computing engine (ACE) integrated circuit and may include configuration information, operand data, and may also include routing and power control information. The ACE IC comprises a plurality of heterogeneous computational elements coupled to an interconnection network. The plurality of heterogeneous computational elements include corresponding computational elements having fixed and differing architectures, such as fixed architectures for different functions such as memory, addition, multiplication, complex multiplication, subtraction, configuration, reconfiguration, control, input, output, and field programmability. In response to configuration information, the interconnection network is operative to configure the plurality of heterogeneous computational elements for a plurality of different functional modes.

Training a wireless sensor network

Abstract: The networks considered in this paper consist of tiny energy-constrained commodity sensors massively deployed, along with one or more sink nodes providing interface to the outside world. Our contribution is to propose a scalable energy-efficient training protocol for nodes that are initially anonymous, asynchronous and unaware of their location. Our training protocol imposes a flexible and intuitive coordinate system onto the deployment area and partitions the anonymous nodes into clusters where data can be gathered from the environment and synthesized under local control. An important by-product of the training protocol is a simple and natural data fusion protocol as well as an energy-efficient protocol for routing data from clusters to the sink node. Being energy-efficient, our training protocol can be run on either a scheduled or ad-hoc basis to provide robustness and dynamic reconfiguration. We also outline a way of making the training protocol secure by using a parameterized variant of frequency hopping.

Fast reconfiguration of distribution systems considering loss minimization

Abstract: This paper addresses the problem of finding the state of switching devices (open or closed) in primary distribution networks so that the total loss is minimum. Radiality and capacity constraints are taken into account. This optimization problem is a mixed-integer nonlinear optimization problem, in which the integer variables represent the state of the switches, and the continuous variables represent the current flowing through the branches. The standard Newton method (with second derivatives) is used to compute branch currents at each stage within the integer search, which, in turn, is implemented as a simple best-first search. Although a best-first search cannot normally guarantee the optimality of the solution, the high quality of the suboptimal solutions found, together with the high processing speed, make this approach very attractive for real-size distribution systems. Results from the application of the proposed methodology to a 1128-branch, 129-switch, real-world distribution system are presented and discussed.

Control Reconfiguration of Dynamical Systems: Linear Approaches and Structural Tests

Abstract: Introduction to Control Reconfiguration.- Literature Overview.- Part I. Reconfiguration Problem.- Running Example: the 2-Tank System.- General Reconfiguration Problem.- Part II. Linear Solution Approaches.- Direct Reconfiguration Using a Static Block.- Reconfiguration Using a Virtual Sensor.- Reconfiguration Using a Virtual Actuator.- Reconfiguration with Set-Point Tracking.- Reconfiguration by Disturbance Decoupling.- Part III. Structural Tests for Control Reconfiguration.- Structural Models.- Basic Structural Properties.- Solvability of Disturbance Decoupling.- Structural Solutions to Disturbance Decoupling.- A Structural Reconfiguration Algorithm for Actuator Faults.- Part IV. Application Examples.- Reconfiguration of the 3-Tank System.- Reconfiguration of a Helicopter Model.- Conclusion.

Optimal reconfiguration of radial distribution systems using a fuzzy mutated genetic algorithm

Abstract: A new method based on a fuzzy mutated genetic algorithm for optimal reconfiguration of radial distribution systems (RDS) is presented. The proposed algorithm overcomes the combinatorial nature of the reconfiguration problem and deals with noncontinuous multi-objective optimization. The attractive features of the algorithm are: preservation of radial property of the network without islanding any load point by an elegant coding scheme and an efficient convergence characteristic attributed to a controlled mutation using fuzzy logic.

Wireless sensor networks for health monitoring

Abstract: We propose a platform for health monitoring using wireless sensor networks. Our platform is a new architecture called CustoMed that will reduce the customization and reconfiguration time for medical systems that use reconfigurable embedded systems. This architecture is a network enabled system that supports various wearable sensors and contains on-board general computing capabilities for executing individually tailored event detection, alerts, and network communication with various medical informatics services. The customization of such system with a large number of "med nodes" is extremely fast even by non-engineering staff. In this paper, we present the architecture of such device along with experimental analysis that evaluates the performance of such system.

Selection of partners in virtual enterprise paradigm

Abstract: Agility is the competitive advantage in the global manufacturing environment. It is believed that the agility can be realized by dynamically reconfigurable virtual enterprise. However, the configuration of virtual enterprises is a challenge to us. In selecting the partners for the reconfiguration of virtual enterprise, many factors should be taken into consideration. However, the manufacturing cost and time to market are the most important factors. In this paper, in considering the completion time as a constraint we model the partner selection problem by an integer programming formulation to minimize the manufacturing cost. The formulation is then transformed into a graph-theoretical formulation and a 2-phase algorithm is developed to solve the problem. In the first phase, a polynomial bounded algorithm is proposed to find the earliest completion time, so we obtained a feasible solution. In phase 2, we improve the solution by exchanging the candidate partners in keeping the solution in the feasible region. Although we may not find the optimal solution for the problem by the improvement algorithm, the objective is reduced iteration by iteration. Thus, the algorithm is efficient and can be applicable to practical problems. An illustrative example is presented to show the application of the proposed algorithm.

REPLICA: a bitstream manipulation filter for module relocation in partial reconfigurable systems

Abstract: The feature of partial reconfiguration provided by currently available field programmable gate arrays (FPGAs) makes it possible to change hardware modules while others keep working. The combination of this feature and the high gate capacity enables the integration of dynamic systems that can be adapted to changing demands during runtime. Placing the dynamically changing modules along a horizontal communication infrastructure does not only provide communication facilities it also enables the relocation of pre-synthesized modules by bitstream manipulations. The exact placement of an incoming module is determined according to the current resource allocation, which results in an online placement problem. In order to prevent any extra configuration overhead for the relocation process, we developed the REPLICA (relocation per online configuration alteration) filter, which is capable of performing the necessary bitstream manipulations during the regular download process. The filter architecture, a configuration manager and an evaluation example are presented in this paper.

Efficient datapath merging for partially reconfigurable architectures

Abstract: Reconfigurable systems have been shown to achieve significant performance speedup through architectures that map the most time-consuming application kernel modules or inner loops to a reconfigurable datapath. As each portion of the application starts to execute, the system partially reconfigures the datapath so as to perform the corresponding computation. The reconfigurable datapath should have as few and simple hardware blocks and interconnections as possible, in order to reduce its cost, area, and reconfiguration overhead. To achieve that, hardware blocks and interconnections should be reused as much as possible across the application. We represent each piece of the application as a data-flow graph (DFG). The DFG merging process identifies similarities among the DFGs, and produces a single datapath that can be dynamically reconfigured and has a minimum area cost, when considering both hardware blocks and interconnections. In this paper we present a novel technique for the DFG merge problem, and we evaluate it using programs from the MediaBench benchmark. Our algorithm execution time approaches the fastest previous solution to this problem and produces datapaths with an average area reduction of 20%. When compared to the best known area solution, our approach produces datapaths with area costs equivalent to (and in many cases better than) it, while achieving impressive speedups.

Physically-aware HW-SW partitioning for reconfigurable architectures with partial dynamic reconfiguration

Abstract: Many reconfigurable architectures offer partial dynamic configurability, but current system-level tools cannot guarantee feasible implementations when exploiting this feature. We present a physically aware hardware-software (HW-SW) scheme for minimizing application execution time under HW resource constraints, where the HW is a reconfigurable architecture with partial dynamic reconfiguration capability. Such architectures impose strict placement constraints that lead to implementation infeasibility of even optimal scheduling formulations that ignore the nature of these constraints. We propose an exact and a heuristic formulation that simultaneously partition, schedule, and do linear placement of tasks on such architectures. With our exact formulation, we prove the critical nature of placement constraints. We demonstrate that our heuristic generates high-quality schedules by comparing the results with the exact formulation for small tests and a popular, but placement-uanaware scheduling heuristic for larger tests. With a case study, we demonstrate extension of our approach to handle heterogenous architectures with specialized resources distributed between general purpose programmable logic columns. The execution time of our heuristic is very reasonable- task graphs with hundreds of nodes are processed in a couple of minutes.

Control and learning of ambience by an intelligent building

Abstract: Modern approaches to the architecture of living and working environments emphasize the dynamic reconfiguration of space and function to meet the needs, comfort, and preferences of its inhabitants. Although it is possible for a human operator to specify a configuration explicitly, the size, sophistication, and dynamic requirements of modern buildings demands that they have autonomous intelligence that could satisfy the needs of its inhabitants without human intervention. We describe a multiagent framework for such intelligent building control that is deployed in a commercial building equipped with sensors and effectors. Multiple agents control subparts of the environment using fuzzy rules that link sensors and effectors. The agents communicate with one another by asynchronous, interest-based messaging. They implement a novel unsupervised online real-time learning algorithm that constructs a fuzzy rule-base, derived from very sparse data in a nonstationary environment. We have developed methods for evaluating the performance of systems of this kind. Our results demonstrate that the framework and the learning algorithm significantly improve the performance of the building.

A decomposition approach to optimal remote controlled switch allocation in distribution systems

Abstract: The growing demand for improved quality of service increases the importance of network automation, namely the investment in remote-controlled switch (RCS) devices. These allow improving the fault isolation and reconfiguration time and therefore increasing the system quality of service. The investment in switch devices comes at a cost and thus must be optimized. The problem of determining the optimal number of devices and their optimal location is a difficult problem: the solution space is combinatorial and the objective function is nonanalytical. We propose to address this problem in a two-stage decomposition approach. Results are presented to i) divide the solution space into independent subspaces, and then ii) solve the optimization problems in each subspace. The solution approach is illustrated for a real distribution network problem.

Reconfigurable architectures for bio-sequence database scanning on FPGAs

Abstract: Protein sequences with unknown functionality are often compared to a set of known sequences to detect functional similarities. Efficient dynamic-programming algorithms exist for solving this problem, however current solutions still require significant scan times. These scan time requirements are likely to become even more severe due to the rapid growth in the size of these databases. In this paper, we present a new approach to bio-sequence database scanning using re-configurable field-programmable gate array (FPGA)-based hardware platforms to gain high performance at low cost. Efficient mappings of the Smith-Waterman algorithm using fine-grained parallel processing elements (PEs) that are tailored toward the parameters of a query have been designed. We use customization opportunities available at run time to dynamically reconfigure the PEs to make better use of available resources. Our FPGA implementation achieves a speedup of approximately 170 for linear gap penalties and 125 for affine gap penalties compared to a standard desktop computing platform. We show how run-time reconfiguration can be used to further improve performance.

Network configuration management via model finding

Abstract: Complex, end-to-end network services are set up via the configuration method: each component has a finite number of configuration parameters each of which is set to a definite value. End-to-end network service requirements can be on connectivity, security, performance and fault-tolerance. However, there is a large conceptual gap between end-to-end requirements and detailed component configurations. To bridge this gap, a number of subsidiary requirements are created that constrain, for example, the protocols to be used, and the logical structures and associated policies to be set up at different protocol layers. By performing different types of reasoning with these requirements, different configuration tasks are accomplished. These include configuration synthesis, configuration error diagnosis, configuration error fixing, reconfiguration as requirements or components are added and deleted, and requirement verification. However, such reasoning is currently ad hoc. Network requirements are not even precisely specified hence automation of reasoning is impossible. This is a major reason for the high cost of network management and total cost of ownership. This paper shows how to formalize and automate such reasoning using a new logical system called Alloy. Alloy is based on the concept of model finding. Given a first-order logic formula and a domain of interpretation, Alloy tries to find whether the formula is satisfiable in that domain, i.e., whether it has a model. Alloy is used to build a Requirement Solver that takes as input a set of network components and requirements upon their configurations and determines component configurations satisfying those requirements. This Solver is used in different ways to accomplish the above reasoning tasks. The Solver is illustrated in depth by carrying out a variety of these tasks in the context of a realistic fault-tolerant virtual private network with remote access. Alloy uses modern satisfiability solvers that solve millions of constraints in millions of variables in seconds. However, poor requirements can easily nullify such speeds. The paper outlines approaches for writing efficient requirements. Finally, it outlines directions for future research.

Robust Integrated Flight Control Design Under Failures, Damage, and State-Dependent Disturbances

Abstract: Ar obust integrated fault-tolerant flight control system is presented that accommodates different types of actuator failures and control effector damage, even while rejecting state-dependent disturbances. It is shown that a decentralized failure detection, identification, and reconfiguration system, combined judiciously with adaptive laws for damage estimates and variable structure adjustment laws for disturbance estimates, yields a stable system despite simultaneous presence of failures, damage and disturbances. The proposed system is well suited for the case of first-order actuator dynamics. The properties of the proposed algorithms are illustrated on a medium-fidelity nonlinear simulation of Boeing’s Tailless Advanced Fighter Aircraft.

Dynamic interconnection of reconfigurable modules on reconfigurable devices

Abstract: This article presents two approaches to solving the problem of communication between components dynamically placed at runtime on a reconfigurable device. The first is a circuit-routing approach designed for existing FPGAs. This approach uses the reconfigurable multiple bus (RMB). The second, network-based approach targets devices with unlimited reconfiguration capability such as coarse-grained reconfigurable devices. We introduce the dynamic network on chip (DyNoC) as a viable communication infrastructure for communication on dynamically reconfigurable devices. For prototyping the DyNoC on FPGAs, we design and implement an unrestricted communication model for a columnwise-reconfigurable chip. For the DyNoC, as well as for the RMB on chip (RMBoC), we provide algorithms and implementation results from real-life problems.

Control Issues in Systems with Loop Delays

Abstract: This chapter discusses properties of feedback control systems containing loop delays (dead-time systems) and approaches to controller design for such systems. Consider the feedback system depicted in Fig. 1, where P is a plant, C is a controller, r is a reference signal, d is a disturbance, u is a control signal, and y is an output (measurement) signal. It is assumed throughout that both the measured signal y and the control signal u are delayed by hy and hu units of time, respectively. This is reflected in Fig. 1 by the two delay blocks containing the delay element Dh defined by

Scalable reconfigurable equipment design principles

Abstract: Scalability is one of six key characteristics found in reconfigurable manufacturing systems. Scalable systems satisfy changing capacity requirements efficiently through system reconfiguration, and in the flexible manufacturing literature this capability is called expansion flexibility. The development of modular scalable machine tools is a necessary precursor to achieving scalable systems. Unfortunately, there is little work describing the design of scalable machines. This paper establishes the need for scalable machines and a basis for evaluating and describing them. Applicable metrics are defined, and an architecture for scalable machines is presented. Two examples illustrate the scalable architecture. Finally, a design parameter based on a mathematical approach is presented to determine the optimal number of modules to be included on a modular scalable machine. This as a design parameter is important because it limits machine size and the number of module interfaces included in the base machine structure.