A Hardware Time Manager Implementation for the Xenomai Real-Time Kernel of Embedded Linux

Nowadays, the use of embedded operating systems in different embedded projects is subject to a tremendous growth. Embedded Linux is becoming one of those most popular EOSs due to its modularity, efficiency, reliability, and cost. One way to make it hard real-time is to include a real-time kernel like Xenomai. One of the key characteristics of a Real-Time Operating System (RTOS) is its ability to meet execution time deadlines deterministically. So, the more precise and flexible the time management can be, the better it can handle efficiently the determinism for different embedded applications. RTOS time precision is characterized by a specific periodic interrupt service controlled by a software time manager. The smaller the period of the interrupt, the better the precision of the RTOS, the more it overloads the CPU, and though reduces the overall efficiency of the RTOS. In this paper, we propose to drastically reduce these overheads by migrating the time management service of Xenomai into a configurable hardware component to relieve the CPU. The hardware component is implemented in a Field Programmable Gate Array coupled to the CPU. This work was achieved in a Master degree project where students could apprehend many fields of embedded systems: RTOS programming, hardware design, performance evaluation, etc.Comment: Embed With Linux (EWiLi) workshop, Lorient : France (2012

Enabling Flexibility through Forming and Evolving Systems of Systems

Flexibility is a highly desired attribute of many systems operating in changing or uncertain conditions. This paper presents a study of enabling flexibility through designing and operating systems of systems (SoSs). The paper analyzes flexibility mechanisms of SoSs and, accordingly, identifies needs for flexibility that SoSs can meet. Following that, it proposes a hierarchical network as a more flexible SoS architecture for complex or distributed large-scale systems. Then, decision problems for forming and evolving a SoS network are defined. A case that involves integrating distributed renewable energy sources with the main grid is presented to illustrate the implementation of the proposed methodology. Results from this study support the idea of acquiring and maintaining flexibility with SoSs. The paper also identifies research needs for advancing this particular use of SoSs

Fewer Mistakes on the First Day: Architectural Strategies and Their Impacts on Acquisition Outcomes

Tenth Annual Acquisition Research Symposium Acquisition ManagementExcerpt from the Proceedings of the Tenth Annual Acquisition Research Symposium Acquisition ManagementNaval Postgraduate School Acquisition Research ProgramPrepared for the Naval Postgraduate School, Monterey, CANaval Postgraduate School Acquisition Research ProgramApproved for public release; distribution is unlimited

Software dependability modeling using an industry-standard architecture description language

Performing dependability evaluation along with other analyses at architectural level allows both making architectural tradeoffs and predicting the effects of architectural decisions on the dependability of an application. This paper gives guidelines for building architectural dependability models for software systems using the AADL (Architecture Analysis and Design Language). It presents reusable modeling patterns for fault-tolerant applications and shows how the presented patterns can be used in the context of a subsystem of a real-life application

Modellability of System Characteristics - Using Formal Mark-up Languages for Change Capability by Design

AbstractChange capability enables a production system to cope with external influences in an efficient, fast and self-organized manner. Several approaches have been designed for measuring change capability by specific indicators which represent core characteristics of production systems. On the other hand, formal modelling languages are used for production system design. Unfortunately, these languages do not match with system characteristics and especially with those indicators of change capability. Due to this missing linkage, existent production system models don’t facilitate the implementation of a system's change capability by design. Goal of this contribution is to point out the possibilities of operationalization approaches and their potential to be extended for (formal) modelling of system characteristics and sub properties, exemplified by using the concept of change capability. Additionally, the potential of change capability to be representable in a formal language will be exemplarily outlined by emphasizing on Systems Modelling Language (SysML). For this purpose, a qualitative approach with an emphasis on literature- and content analysis will be applied. Results of this contribution are (1) to pinpoint the research gap (which is also of crucial practical relevance) and (2) to point out possible solution approaches for a formal modellability of system characteristics

On cost-effective reuse of components in the design of complex reconfigurable systems

Design strategies that benefit from the reuse of system components can reduce costs while maintaining or increasing dependability—we use the term dependability to tie together reliability and availability. D3H2 (aDaptive Dependable Design for systems with Homogeneous and Heterogeneous redundancies) is a methodology that supports the design of complex systems with a focus on reconfiguration and component reuse. D3H2 systematizes the identification of heterogeneous redundancies and optimizes the design of fault detection and reconfiguration mechanisms, by enabling the analysis of design alternatives with respect to dependability and cost. In this paper, we extend D3H2 for application to repairable systems. The method is extended with analysis capabilities allowing dependability assessment of complex reconfigurable systems. Analysed scenarios include time-dependencies between failure events and the corresponding reconfiguration actions. We demonstrate how D3H2 can support decisions about fault detection and reconfiguration that seek to improve dependability while reducing costs via application to a realistic railway case study

Context-aware adaptation in DySCAS

DySCAS is a dynamically self-configuring middleware for automotive control systems. The addition of autonomic, context-aware dynamic configuration to automotive control systems brings a potential for a wide range of benefits in terms of robustness, flexibility, upgrading etc. However, the automotive systems represent a particularly challenging domain for the deployment of autonomics concepts, having a combination of real-time performance constraints, severe resource limitations, safety-critical aspects and cost pressures. For these reasons current systems are statically configured. This paper describes the dynamic run-time configuration aspects of DySCAS and focuses on the extent to which context-aware adaptation has been achieved in DySCAS, and the ways in which the various design and implementation challenges are met