Model-integrated embedded systems

Abstract. Model-Integrated Computing is a proven technology for designing and implementing complex software systems. Making the designtime models available at run-time benefits the development of dynamic embedded systems. This paper describes a paradigm-independent, general infrastructure for the design and implementation of model-integrated embedded systems that is highly applicable to self-adaptive systems.

Robust multi-hop time synchronization in sensor networks

Abstract- The possibility of establishing the chronology of events in a widely distributed network, or even stronger, the time synchronization of all nodes in the network is often needed for applications of wireless sensor networks. In this paper we describe the Flooding Time Synchronization Protocol (FTSP) that provides time synchronization service in such networks. The protocol was designed to utilize low communication bandwidth, scale well for medium sized multi-hop networks, and be robust against topology changes and node failures. The FTSP achieves its robustness by utilizing periodic radio broadcast of synchronization messages and implicit dynamic topology update. MAC-layer time-stamping, comprehensive compensation of errors and linear regression are used to achieve high accuracy. The resulting time synchronization error of the FTSP is significantly lower than that of the existing RBS and TPSN algorithms. The data from a comprehensive multi-hop experiment shows the average network-wide synchronization error to be in the microsecond range. The protocol was further validated as part of our countersniper system that was field tested in a US military facility. 1

Robust multi-hop time synchronization in sensor networks

Abstract – The possibility of establishing the chronology of events in a widely distributed network, or even stronger, the clock synchronization of all nodes in the network is often needed for applications of wireless sensor networks (WSN). In this paper we describe the Flooding Time Synchronization Protocol (FTSP) that provides clock synchronization service in such networks. The protocol was designed to utilize low communication bandwidth, scale well for medium sized multi-hop networks, and be robust against topology changes and node failures. The robustness of the protocol is due to the periodic radio broadcast of synchronization messages and the implicit dynamic topology update. MAC-layer time-stamping, comprehensive compensation of errors and linear regression are used to achieve high accuracy of the clock synchronization. The data from a comprehensive multi-hop experiment shows that the average network-wide synchronization error is less than two microseconds per hop. The protocol was further validated as part of our countersniper system that was field tested in a US military facility. 1

High-Accuracy Differential Tracking of Low-Cost GPS Receivers

In many mobile wireless applications such as the automated driving of cars, formation flying of unmanned air vehicles, and source localization or target tracking with wireless sensor networks, it is more important to know the precise relative locations of nodes than their absolute coordinates. GPS, the most ubiquitous localization system available, generally provides only absolute coordinates. Furthermore, low-cost receivers can exhibit tens of meters of error or worse in challenging RF environments. This paper presents an approach that uses GPS to derive relative location information for multiple receivers. Nodes in a network share their raw satellite measurements and use this data to track the relative motions of neighboring nodes as opposed to computing their own absolute coordinates. The system has been implemented using a network of Android phones equipped with a custom Bluetooth headset and integrated GPS chip to provide raw measurement data. Our evaluation shows that centimeter-scale tracking accuracy at an update rate of 1 Hz is possible under various conditions with the presented technique. This is more than an order of magnitude more accurate than simply taking the difference of reported absolute node coordinates or other simplistic approaches due to the presence of uncorrelated measurement errors

Model Reuse with Metamodel-Based Transformations

Abstract. Metamodel-based transformations permit descriptions of mappings between models created using different concepts from possibly overlapping domains. This paper describes the basic algorithms used in matching metamodel constructs, and how this match is to be applied. The transformation process facilitates the reuse of models specified in one domain-specific modeling language in another context: another domain-specific modeling language. UML class diagrams are used as the language of the metamodels. The focus of the paper is on the matching and firing of transformation rules, and on finding efficient and generic algorithms. An illustrative case study is provided.

On Metamodel Composition

Abstract-- Computer-based systems (CBS) development integrates various disciplines, such as hardware design, software engineering, and performance modeling, as well as the “base ” engineering discipline in which the CBS will operate. As such, use of a “non-native ” modeling language is not acceptable when performing CBS design, and rapid specification and development of domain-specific modeling languages (DSMLs) is necessary. We advocate a UML-based metamodeling technique to DSML specification and generation. A key feature of our approach is the composition of new metamodels from existing metamodels through the use of three newly defined UML operators—equivalence, implementation inheritance, and interface inheritance. This paper describes the development of these new operators, details how they are used in metamodel composition, and presents examples of metamodel composition. Index terms--metamodeling, model composition, model-based computing, UML I