2011
In model-based development, verification techniques can be used to check whether an abstract model satisfies a set of properties. Ideally, implementation code generated from these models can also be verified against similar properties. However, the distance between the property specification languages and the implementation makes verifying such generated code difficult. Optimizations and renamings can blur the correspondence between the two, further increasing the difficulty of specifying verification properties on the generated code. This paper describes methods for specifying verification properties on abstract models that are then checked on implementation level code. These properties are translated by an extended code generator into implementation code and special annotations that are used by a software model checker.
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Predictable deployment in component-based enterprise distributed real-time and embedded systems
Component-based middleware, such as the Lightweight CORBA Component
Model, are increasingly used to implement large-scale distributed
real-time and embedded (DRE) systems. In addition to supporting the quality of
service (QoS) requirements of individual DRE systems, component
technologies must also support bounded latencies when effecting
deployment changes to DRE systems in response to changing
environmental conditions and operational requirements.
This paper makes three contributions to the study of predictable
deployment latencies in DRE systems. First, we describe OMG's Deployment and Configuration (D\&C)
specification for component-based systems and discuss how conventional
implementations of this standard can significantly degrade deployment
latencies. Second, we describe architectural changes and performance
optimizations implemented within the Locality-Enhanced Deployment and
Configuration Engine (LE-DAnCE) implementation of the D\&C
specification. Finally, we analyze the performance of LE-DAnCE in the
context of component deployments on 10 nodes for a representative DRE system
consisting of 1,000 components. Our results show LE-DAnCE's optimizations
provide a bounded deployment latency of less than 2 seconds with 4 percent
jitter.
The rapidly increasing use of information technology in constructing real-world systems has led to the urgent need for a sound systematic approach in designing networked control systems. Communication delays and other uncertainties complicate the development and analysis of these systems. This paper describes a prototype modeling language for the design of networked control systems using passivity to decouple the control design from network uncertainties. The modeling language includes an integrated analysis tool to check for passivity and code generators for simulation in MATLAB/Simulink using the
TrueTime platform modeling toolbox and for running actual experiments. The resulting designs are by construction robust to platform effects and implementation uncertainties.
This paper is aimed at presenting a concept of a flexible diagramming framework for building engineering and educational applications. The framework was designed to serve as a platform for online services and collaborative environments where users typically work on remotely stored, shared data through a browser-based user interface. The paper summarizes the common requirements towards such services, overviews related approaches and gives insights into some design challenges through the analysis of use-cases. The design problem is examined from a user-centered view: the key motivation of our research is to find innovative, possibly device-independent solutions that enable seamless user experiences. Finally a generic framework based on a HTML-JavaScript library is proposed, which could be employed for implementing wide range of software solutions from e-learning to cloud-based modeling environments.
Traditional wireless sensor network architectures are based
on low-power microcontrollers and highly integrated short range radio
transceiver chips operating in one of the few ISM bands. This combination
provides a convenient and proven approach to design and build
inexpensive sensor nodes rapidly. However, the black box nature of these
radio chips severely limit experimentation and research with novel and innovative
technologies in the wireless infrastructure. Our team previously
proposed a revolutionary architecture for wireless nodes based on Flash
FPGA devices. This paper shows the rst results of our work through
the implementation and evaluation of a simple baseband FSK modem
in the SmartFusion FPGA fabric. We also demonstrate how we could
leverage existing software radio projects to use the baseband modem in
a wide range of radio frequency bands.
In large programs such as NASA Exploration, multiple systems that interact via safety-critical protocols are already designed with different Statechart variants. To verify these safety-critical systems, a unified framework is needed based on a formal semantics that captures the variants of Statecharts. We describe Polyglot, a unified framework for the analysis of models described using multiple Statechart formalisms. In this framework, Statechart models are translated into Java and analyzed using pluggable semantics for different variants operating in a polymorphic execution environment. The framework has been built on the basis of a parametric formal semantics that captures the common core of Statecharts with extensions for different variants, and addresses previous limitations. Polyglot has been integrated with the Java Jathfinder verification tool-set, providing analysis and test-case generation capabilities. We describe the application of this unified framework to the analysis of NASA/JPL's MER Arbiter whose interacting components were modeled using multiple Statechart formalisms.
The paper presents a novel sensor fusion technique
to shooter localization using a wireless network of single-channel
acoustic sensors. The unique challenge is that the number of
available sensors is very limited. The first contribution of the
work is an approach to estimate the miss distance of the shot and
the range to the shooter from a single shot using a single sensor.
The second contribution is the novel sensor fusion algorithm
itself that fuses the miss distance and range estimates of the
individual nodes as well as their Time of Arrival observations of
the shockwave and the muzzle blast. The performance of both the
single sensor method and the network fusion are very promising.
Metamodeling is foundational to many modeling frameworks, and so it is important to formalize and reason about it. Ideally, correctness proofs and test-case generation on the metamodeling framework should be automatic. However, it has yet to be shown that extensive automated reasoning on metamodeling frameworks can be achieved. In this paper we present one approach to this problem: Metamodeling frameworks are specified modularly using algebraic data types and constraint logic programming (CLP). Proofs and test-case generation are encoded as CLP satisfiability problems and automatically solved.
Enterprise distributed real-time and embedded (DRE) systems are
increasingly being developed with the use of component-based software
techniques. Unfortunately, commonly used component middleware platforms
provide limited support for event-based publish/subscribe (pub/sub)
mechanisms that meet both quality-of-service (QoS) and configurability
requirements of DRE systems. On the other hand, although pub/sub technologies,
such as OMG Data Distribution Service (DDS), support a wide range of QoS
settings, the level of abstraction they provide make it hard to configure them
due to the significant source-level configuration that must be hard-coded at
compile time or tailored at run-time using proprietary, ad hoc configuration
logic. Moreover, developers of applications using native pub/sub technologies
must write large amounts of boilerplate ``glue'' code to support run-time
configuration of QoS properties, which is tedious and error-prone. This paper
describes a novel, generative approach that combines the strengths of
QoS-enabled pub/sub middleware with component-based middleware technologies.
In particular, this paper describes the design and implementation of DDS4CIAO
which addresses a number of inherent and accidental complexities in the DDS4CCM
standard. DDS4CIAO simplifies the development, deployment, and configuration
of component-based DRE systems that leverage DDS's powerful QoS capabilities by
provisioning DDS QoS policy settings and simplifying the development of DDS
applications.
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Acoustic Shooter Localization with a Minimal Number of Single-Channel Wireless Sensor Nodes
Acoustic shooter localization systems are being rapidly deployed in the field. However, these are standalone systems—either wearable or vehicle-mounted—that do not have networking capability even though the advantages of widely distributed sensing for locating shooters have been demonstrated before. The reason for this is that certain disadvantages of wireless network-based prototypes made them impractical for the military. The system that utilized stationary single-channel sensors required many sensor nodes, while the multi-channel wearable version needed to track the absolute self-orientation of the nodes continuously, a notoriously hard task. This paper presents an approach that overcomes
the shortcomings of past approaches. Specifically, the technique requires as few as five single-channel wireless sensors to provide accurate shooter localization and projectile trajectory estimation. Caliber estimation and weapon classification are also supported. In addition, a single node alone can provide reliable miss distance and range estimates based on a single shot as long as a reasonable assumption holds. The main contribution of the work and the focus of this paper is the novel sensor fusion technique that works well with a limited number of observations. The technique is thoroughly evaluated using an extensive shot library.
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