PROPOSED MIDDLEWARE SOLUTION FOR RESOURCE-CONSTRAINED DISTRIBUTED EMBEDDED NETWORKS

The explosion in processing power of embedded systems has enabled distributed embedded networks to perform more complicated tasks. Middleware are sets of encapsulations of common and network/operating system-specific functionality into generic, reusable frameworks to manage such distributed networks. This thesis will survey and categorize popular middleware implementations into three adapted layers: host-infrastructure, distribution, and common services. This thesis will then apply a quantitative approach to grading and proposing a single middleware solution from all layers for two target platforms: CubeSats and autonomous unmanned aerial vehicles (UAVs). CubeSats are 10x10x10cm nanosatellites that are popular university-level space missions, and impose power and volume constraints. Autonomous UAVs are similarly-popular hobbyist-level vehicles that exhibit similar power and volume constraints. The MAVLink middleware from the host-infrastructure layer is proposed as the middleware to manage the distributed embedded networks powering these platforms in future projects. Finally, this thesis presents a performance analysis on MAVLink managing the ARM Cortex-M 32-bit processors that power the target platforms

Services in pervasive computing environments : from design to delivery

The work presented in this thesis is based on the assumption that modern computer technologies are already potentially pervasive: CPUs are embedded in any sort of device; RAM and storage memory of a modern PDA is comparable to those of a ten years ago Unix workstation; Wi-Fi, GPRS, UMTS are leveraging the development of the wireless Internet. Nevertheless, computing is not pervasive because we do not have a clear conceptual model of the pervasive computer and we have not tools, methodologies, and middleware to write and to seamlessly deliver at once services over a multitude of heterogeneous devices and different delivery contexts. Our thesis addresses these issues starting from the analysis of forces in a pervasive computing environment: user mobility, user profile, user position, and device profile. The conceptual model, or metaphor, we use to drive our work is to consider the environment as surrounded by a multitude of services and objects and devices as the communicating gates between the real world and the virtual dimension of pervasive computing around us. Our thesis is thus built upon three main “pillars”. The first pillar is a domain-object-driven methodology which allows developer to abstract from low level details of the final delivery platform, and provides the user with the ability to access services in a multi-channel way. The rationale is that domain objects are self-contained pieces of software able to represent data and to compute functions and procedures. Our approach fills the gap between users and domain objects building an appropriate user interface which is both adapted to the domain object and to the end user device. As example, we present how to design, implement and deliver an electronic mail application over various platforms. The second pillar of this thesis analyzes in more details the forces that make direct object manipulation inadequate in a pervasive context. These forces are the user profile, the device profile, the context of use, and the combinatorial explosion of domain objects. From the analysis of the electronic mail application presented as example, we notice that according to the end user device, or according to particular circumstances during the access to the service (for instance if the user access the service by the interactive TV while he is having his breakfast) some functionalities are not compulsory and do not fit an adequate task sequence. So we decided to make task models explicit in the design of a service and to integrate the capability to automatically generate user interfaces for domain objects with the formal definition of task models adapted to the final delivery context. Finally, the third pillar of our thesis is about the lifecycle of services in a pervasive computing environment. Our solutions are based upon an existing framework, the Jini connection technology, and enrich this framework with new services and architectures for the deployment and discovery of services, for the user session management, and for the management of offline agents

A framework for flexible integration in robotics and its applications for calibration and error compensation

Robotics has been considered as a viable automation solution for the aerospace industry to address manufacturing cost. Many of the existing robot systems augmented with guidance from a large volume metrology system have proved to meet the high dimensional accuracy requirements in aero-structure assembly. However, they have been mainly deployed as costly and dedicated systems, which might not be ideal for aerospace manufacturing having low production rate and long cycle time. The work described in this thesis is to provide technical solutions to improve the flexibility and cost-efficiency of such metrology-integrated robot systems. To address the flexibility, a software framework that supports reconfigurable system integration is developed. The framework provides a design methodology to compose distributed software components which can be integrated dynamically at runtime. This provides the potential for the automation devices (robots, metrology, actuators etc.) controlled by these software components to be assembled on demand for various assembly applications. To reduce the cost of deployment, this thesis proposes a two-stage error compensation scheme for industrial robots that requires only intermittent metrology input, thus allowing for one expensive metrology system to be used by a number of robots. Robot calibration is employed in the first stage to reduce the majority of robot inaccuracy then the metrology will correct the residual errors. In this work, a new calibration model for serial robots having a parallelogram linkage is developed that takes into account both geometric errors and joint deflections induced by link masses and weight of the end-effectors. Experiments are conducted to evaluate the two pieces of work presented above. The proposed framework is adopted to create a distributed control system that implements calibration and error compensation for a large industrial robot having a parallelogram linkage. The control system is formed by hot-plugging the control applications of the robot and metrology used together. Experimental results show that the developed error model was able to improve the 3 positional accuracy of the loaded robot from several millimetres to less than one millimetre and reduce half of the time previously required to correct the errors by using only the metrology. The experiments also demonstrate the capability of sharing one metrology system to more than one robot

VR-LAB: A Distributed Multi-User Environment for Educational Purposes and Presentations

In the last three years our research was focused on a new distributed multi-user environment. Finally, all components were integrated in a system called the VR-Lab, which will be described on the following pages. The VR-Lab provides Hard- and Software for a distributed presentation system. Elements which are often used in environments called Computer Supported Cooperative Work (CSCW). In contrast to other projects the VR-Lab integrates a distributed system in a common environment of a lecture room and does not generate a virtual conference room in a computer system. Thus, allowing inexperienced persons to use the VR-LAB and benefit from the multimedia tools in their common environment. To build the VR-LAB we developed a lot of hard- and software and integrated it into a lecture room to perform distributed presentations, conferences or teaching. Additionally other software components were developed to be connected to the VR-LAB, control its components, or distribute content between VR-LAB installations. Beside standard software for video and audio transmission, we developed and integrated a distributed 3D-VRML-Browser to present three dimensional content to a distributed audience. One of the interesting features of this browser is the object oriented distributed scene graph. By coupling a high-speed rendering system with a database we could distribute objects to other participants. So the semantic properties of any geometrical or control object can be kept and used by the remote participant. Because of the high compression achieved by the transport of objects instead of triangles a lot of bandwidth could be saved. Also each participant could select a display quality appropriate to its hardware.Diese Arbeit beschreibt ein integriertes Virtual-Reality System, das VR Lab. Das System besteht aus verschiedenen Hard- und Softwarekomponenten die eine verteiltevirtuelle Multi-User Umgebung darstellen die vor allem im Bereich verteilter Präsentationen verwendet werden kann. Im Gegensatz zu anderen Systemen dieser Art, die oft im Bereich des Computer Supported Cooperative Work (CSCW) eingesetzt werden dient unser System nicht dazu eine Präsentationsumgebung im Computer nachzubilden sondern eine reele Umgebung zu schaffen in der verteilte Präsentationen durchgeführt werden können. Dies soll vor allem ungeübten Personen die Arbeit mit verteilten Umgebungen erleichtern. Dazu wurden verschiedene Hard- und Softwarekomponenten entwickelt. Darunter der verteilte 3D Browser MRT-VR, der es ermöglicht 3D Daten an verschiedenen Stellen gleichzeitig zu visualisieren. MRT-VR zeichnet sich insbesondere dadurch aus, daß die 3D Objekte nicht als Polygondaten transportiert werden, sonderen als Objekte und so deren Objekteigenschaften beibehalten werden. Dies spart nicht nur sehr viel Bandbreite bei der Übertragung sondern ermöglicht auch Darstellungen in unterschiedlichen Qualitätsstufen auf den unterschiedlichen Zielrechnern der Teilnehmer. Ein weiterer Teil der Arbeit beschreibt die Entwicklung einer preiswerten imersiven 3D Umgebung um die 3D Daten in ansprechender Qualität zu visualisieren. Alle Komponenten wurden in einer gemeinsamen Umgebung, dem VR-Lab, integriert und mt Steuerungskomponenten versehen

Web service control of component-based agile manufacturing systems

Current global business competition has resulted in significant challenges for manufacturing and production sectors focused on shorter product lifecyc1es, more diverse and customized products as well as cost pressures from competitors and customers. To remain competitive, manufacturers, particularly in automotive industry, require the next generation of manufacturing paradigms supporting flexible and reconfigurable production systems that allow quick system changeovers for various types of products. In addition, closer integration of shop floor and business systems is required as indicated by the research efforts in investigating "Agile and Collaborative Manufacturing Systems" in supporting the production unit throughout the manufacturing lifecycles. The integration of a business enterprise with its shop-floor and lifecycle supply partners is currently only achieved through complex proprietary solutions due to differences in technology, particularly between automation and business systems. The situation is further complicated by the diverse types of automation control devices employed. Recently, the emerging technology of Service Oriented Architecture's (SOA's) and Web Services (WS) has been demonstrated and proved successful in linking business applications. The adoption of this Web Services approach at the automation level, that would enable a seamless integration of business enterprise and a shop-floor system, is an active research topic within the automotive domain. If successful, reconfigurable automation systems formed by a network of collaborative autonomous and open control platform in distributed, loosely coupled manufacturing environment can be realized through a unifying platform of WS interfaces for devices communication. The adoption of SOA- Web Services on embedded automation devices can be achieved employing Device Profile for Web Services (DPWS) protocols which encapsulate device control functionality as provided services (e.g. device I/O operation, device state notification, device discovery) and business application interfaces into physical control components of machining automation. This novel approach supports the possibility of integrating pervasive enterprise applications through unifying Web Services interfaces and neutral Simple Object Access Protocol (SOAP) message communication between control systems and business applications over standard Ethernet-Local Area Networks (LAN's). In addition, the re-configurability of the automation system is enhanced via the utilisation of Web Services throughout an automated control, build, installation, test, maintenance and reuse system lifecycle via device self-discovery provided by the DPWS protocol...cont'd

A Middleware-centric design methodology for networked embedded systems

Negli ultimi anni \ue8 incrementato considerevolmente l\u2019interesse verso gli \u201dambient intelligence\u201d, sistemi informatici, tipicamente composti da \u201dnetworked embedded systems\u201d (Wirelesse sensor networks, mobile terminal, PDA, etc.) i quali sono integrati nell\u2019ambiente umano con l\u2019obiettivo di migliorare la qualit`a della vita nel modo pi naturale possibile. Una applicazione \u201dNetworked Embedded System\u201d (NES) \ue8 un\u2019applicazione distribuita, eseguita su piattaforme HW/SW eterogenee che interagiscono attraverso differenti canali di comunicazione. Generalmente queste applicazioni per dispositivi NES vengono sviluppate senza il supporto di software di sistema, obbligando il progettista a modellare queste applicazioni utilizzando direttamente le primitive fornite dal sistema operativo embedded o le API dei drivers dei dispositivi HW. Con questa metodologia di progettazione, le applicazioni per sistemi embedded vengono realizzate ad-hoc per la piattaforma HW/SW, risultando essere n\ue9 portabili, n\ue9 scalabili e di conseguenza particolarmente costose. A causa di questi problemi, negli ultimi anni si \ue8 adottato un flusso di progettazione che prevede l\u2019introduzione di un \u201dservice layer\u201d chiamato middleware, il quale astrae le peculiarit del sistema operativo e dei componenti HW, semplificando la progettazione di queste applicazioni embedded. Allo stato dell\u2019arte sono presenti molte implmentazioni di middleware con differenti paradigmi di programmazione, e la scelta di quale utilizzare per progettazione una applicazione NES basata sui seguenti criteri: \u2022 abilit`a/conoscenza/capacit`a di programmazione da parte del progettista; \u2022 piattaforma HW/SW disponinile. Gli svantaggi di questo approccio sono un pi\uf9 complesso flusso di progettazione legato alla mancanza di portabilit\ue0 della stessa applicazione su differenti dispositivi embedded. Questo significa che la presenza del middleware non \ue8 mai stata introdotta nel flusso di progettazione come una esplicita dimensione di progetto. Obiettivo della tesi di dottorato \ue8 lo studio e la realizzazione di un flusso di progettazione per applicazioni per NES, dove il middleware \ue8 una dimensione di progetto, diventando una variabile di progetto come lo sono il software e lo hardware. Questo punto \ue8 ottenuto risolvendo tre problemi: \u2022 Fornire un modello di middleware astratto il quale pu\uf2 essere usato come componente del flusso di progettazione; questo middleware astratto, chiamato Abstract Middleware Services (AMS), fornisce un insieme di servizi astratti basati su differenti paradigmi di programmazione dei middleware reali. Utilizzando questo modello di middleware stratto, il progettista \ue8 facilitato nello sviluppo delle applicazioni per NES. \u2022 Fornire un ambiente di simulazione dove validare e simulare l\u2019intero modello realizzato dal progettista. \u2022 Fornire una metodologia automatica di traduzione da AMS ad un middleware reale, per poter eseguire l\u2019applicazione su una reale piattaforma HW/SW, dotata di un middleware qualsiasi. L\u2019attivit di dototrato ha permesso la definizione di un nuovo approccio di progettazione basato su un modello di middleware astratto che fornisce un ambiente per la modellazione e la validazione di applicazioni per Networked Embedded Systems, risolvendo i tre punti precedenti. Inoltre, al fine di produrre un efficiente ambiente di simulazione e modellazione, sono state analizzate le metodologie di co-simulazione hardware-software-network attualmente presenti in letteratura. L\u2019attivit\ue0 di dottorato inoltre parte integrante del progetto ANGEL finanziato dalla Comunit\ue0 Europea (IST-2005-33506 - Embedded Systems), il cui obiettivo \ue8 lo sviluppo di una piattaforma per la realizzazione di sistemi eterogenei nei quali Wireless Sensor Network (WSN) e tradizionali reti di comunicazioni cooperano per monitorare e migliorare la qualit\ue0 della vita in habitat comuni. Durante questa attivit\ue0 il flusso di progettazione che include anche il middleware come variabile di progetto, oggetto della tesi di dottorato, sar esemplificato su WSN e terminali mobili (per esempio cellulari) per far si che questi possano dialogare tra loro in modo intelligente.Ambient intelligence, pervasive and ubiquitous computing are the center of a great deal of attention because of their promise to bring benefits for end-users, higher revenues for manufacturers and new challenges for researchers. Typical computing technologies (such as telemedicine, manufacturing, crisis management) are part of a broader class of Networked Embedded Systems (NES) in which a large number of nodes are connected together and collaborate to perform a common task under a defined set of constraints. Therefore, the key aspects of these applications are their distributed nature and the presence of very limited HW resources, as in case of WSNs. Their wide adoption requires interoperability across different manufacturers, simplification of application development, simulation tools for functional validation and the fulfilment of tight HW/SW constraints. Interoperability is achieved through the use of standard protocol stacks (e.g., IEEE 802.15.1/Bluetooth and IEEE 802.15.4/Zig- Bee). Simplification of application development can be achieved through a service layer, named middleware, which abstracts from the peculiarities of the operating system and HW components. Traditionally, many NES applications have been developed without support from system software [1] excepts for device drivers and operating systems. State-of-the-art techniques [2] for NES focus on simple data-gathering applications, and in most cases, the design of the application and the system software are usually closely-coupled, or even combined as a monolithic procedure. Such applications are neither flexible nor scalable and they should be re-written if the platform changes. Middleware is emerging as an important architectural component in supporting NES applications able to facilitate the application development. The role of middleware is to present a unified programmingmodel to application designers and to mask out the problems of heterogeneity and distribution providing a basic set of tools and libraries for the low-level handling of technology-specific NES. Several NES middleware have been implemented in the past years each one providing different programming paradigms (e.g., Tuplespace, messageoriented, object-oriented, database, etc.) and differ with respect to ease to use, expressiveness, scalability and overhead. However, their diversity makes the development of high quality middleware-centric software systems complex: software engineering methods and tools should be developed with the use of middleware in mind. In such way, Sensation [xxx] presents a middleware platform solution for pervasive applications inWSN providing a developer-friendly programming interface. This approach is valid just for WSN and does not include a network simulator for an exhaustive network evaluation. Model Driven Architecture (MDA) tries to overcome this problem; MDA is a new way of writing specifications, based on a platform-independent model. A complete MDA specification consists of a platform-independent UML model, one or more platform-specific models, and interface definitions, each describing how the base model is implemented on a different middleware platform. The MDA focuses primarily on the functionality and behaviour of a distributed application or system, not on the technology in which it will be implemented. Furthermore,MDA does not directly provide a simulation environment. Simulation tools are used for validating the application: there is a range of NES simulators available that focus on the network itself. NS-2 is a pure network simulator tool, where the nodes are abstracted and do not run real codes or operating systems, but rather simple behavioral models or statistical traffic generators. The advantage of NS-2 is that scalability is excellent. TOSSIM is a platform-specific simulator environment for sensor networks based on TinyOs operating system. TOSSIM can compile unchanged TinyOS applications directly into its framework, which means that most of the codes written for TOSSIM can be directly used in TinyOS. TOSSIM is a specific simulator for TinyOS and Berkeley motes and cant be used for simulating a generic NES (e.g.,WSN). Finally, SIMICS is a commercial full-system simulator that can be used to simulate heterogenous networked and distributed systems. Complete SW stacks from real system can run on the simulator without any modification. Despite of these punctual contributions, the literature does not report a complete design methodology for NES applications integrating all such three aspects. Therefore, in order to fully support the applications of a great variety of users with different needs, a complete NES application modelling and simulation environment have to include two main components: \u2022 a simulator to validate and explore application functional behaviuor in a network simulated environment supporting interoperability between different implementation platforms and ensure scalability of the NES technology. \u2022 a middleware environemnt providing different programming paradigms. This Layer will serve as an abstraction layer hiding the different NES implementations peculiarities from end-user applications. The goal of this work is to present a middleware-centric design flow for NES, where the middleware plays a decisive role in the design process. The proposed methodology allows programmers to write NES applications by using the system description language named SystemC and the AbstractMiddleware Environment (AME) framework for fast simulation. This proposal has three main advantages: (1) It provides a set of abstract services supporting the programming paradigms of different actual middleware implementations in order to meet the skills of the designer. AME facilitates the NES design flow by providing a unified and developer-common interface concealing the peculiarities of the underlying NES where the simulation environment is modelled in order to simulate the NES applications taking in account hardware and network effects. (2) The application can be simulated at early stage of the design flow for functional validation. (3) automatic mapping of AME applications on the actual platform; this guarantees the correct trade-off between level of abstraction and efficiency of implementation. In the follow we classify the actual middleware approaches according to their programming paradigms; then the AMEcentric design flow is described and finally we report the experimental results

Distributed Discrete Time Network Simulator

The Discrete Time Network Simulator (DTNS) is a System-on-Chip (SoC) simulator developed at Tampere University of Technology. It is used to analyze interconnection architectures and systems built around them. The abstraction level is between the conventional hardware simulators, such as Mentor Graphics ModelSim, and algorithm level simulators, such as Synopsys System Studio. DNTS makes it possible to get cycle-accurate information about the communication while other high-level tools often lack timing completely. This is because DTNS is a time-driven simulator where the simulated time advances in fixed increments of half a clock cycle and the system bus is always simulated at that level of detail. The simulator itself is programmed in C and the system design is described in C or C++ programming language with detail level from high level functional code to almost hardware description language level code. The accuracy of the simulation increases as the model is refined. However, this also makes the simulation times longer. The goal of this thesis work was to develop a distributed version of DTNS as a remedy. The emphasis on the system bus made it a natural point of partitioning. The simulator was split to a central core process and separate processes for system component models which can then be executed in parallel. Processes communicate any writes to the system bus to the core process which then accumulates them and communicates changes to all other processes. At the same time all processes synchronize with the core process after every simulation step. For communication between processes executed on different computers, it was originally given as a premise that Common Object Request Broker Architecture (CORBA) should be used. However, the amount of overhead was found to be too significant and another implementation that communicated directly over the TCP/IP protocol was created, too. For performance testing a statistical model of a H.263 video encoder was used. The model was instrumented to mimic different complexity levels with artificial delays. Multiple simulations was then executed using both communication implementations while varying the delay gradually from very high level and fast model to very complex and slow. Also, the number of computers was varied from one to three. The measured wall clock times of these simulations clearly show the high overhead of CORBA in comparison to TCP/IP. Both implementation were able to speed-up the simulation as the models became slower. The performance of the TCP/IP implementation seems rather impressive. The distribution method of DTNS was also used to distribute a commercial simulator, ModelSim. The system consisted of two to eight TUTWLAN terminal and this was distributed up to eight simulators executed in parallel with signals passed between them using TCP/IP protocol. The simulation times show that this method is capable of significant speed-up even in real world simulations if the system model is in fine enough detail. In conclusion the distribution of DTNS is not very useful in real life as the models are unlikely to be slow enough to see any speed-up. This new version of DTNS is, however, also capable of parallel execution on a single computer with, for example, a multi-core processor and without network overhead simulation times can be improved noticeably even for higher level models. /Kir1

Building object-oriented software with the D-Bus messaging system

Object-oriented programming is a widely adopted paradigm for desktop software development. This paradigm partitions software into separate entities, objects, which consist of data and related procedures used to modify and inspect it. The paradigm has evolved during the last few decades to emphasize decoupling between object implementations, via means such as explicit interface inheritance and event-based implicit invocation. Inter-process communication (IPC) technologies allow applications to interact with each other. This enables making software distributed across multiple processes, resulting in a modular architecture with benefits in resource sharing, robustness, code reuse and security. The support for object-oriented programming concepts varies between IPC systems. This thesis is focused on the D-Bus system, which has recently gained a lot of users, but is still scantily researched. D-Bus has support for asynchronous remote procedure calls with return values and a content-based publish/subscribe event delivery mechanism. In this thesis, several patterns for method invocation in D-Bus and similar systems are compared. The patterns that simulate synchronous local calls are shown to be dangerous. Later, we present a state-caching proxy construct, which avoids the complexity of properly asynchronous calls for object inspection. The proxy and certain supplementary constructs are presented conceptually as generic object-oriented design patterns. The e ect of these patterns on non-functional qualities of software, such as complexity, performance and power consumption, is reasoned about based on the properties of the D-Bus system. The use of the patterns reduces complexity, but maintains the other qualities at a good level. Finally, we present currently existing means of specifying D-Bus object interfaces for the purposes of code and documentation generation. The interface description language used by the Telepathy modular IM/VoIP framework is found to be an useful extension of the basic D-Bus introspection format.Siirretty Doriast

Component-based control system development for agile manufacturing machine systems

It is now a common sense that manufactures including machine suppliers and system integrators of the 21 st century will need to compete on global marketplaces, which are frequently shifting and fragmenting, with new technologies continuously emerging. Future production machines and manufacturing systems need to offer the "agility" required in providing responsiveness to product changes and the ability to reconfigure. The primary aim for this research is to advance studies in machine control system design, in the context of the European project VIR-ENG - "Integrated Design, Simulation and Distributed Control of Agile Modular Machinery"