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  • 1.
    Eriksson, Johan
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Aittamaa, Simon
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Wiklander, Jimmie
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Pietrzak, Pawel
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Lindgren, Per
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    SRP-DM scheduling of component-based embedded real-time software2011Conference paper (Refereed)
    Abstract [en]

    Model and component based design is an established means for the development of large software systems, and is starting to get momentum in the realm of embedded software development. In case of safety critical (dependable systems) it is crucial that the underlying model and its realization captures the requirements on the timely behavior of the system, and that these requirements can be preserved and validated throughout the design process (from specification to actual code execution). To this end, we base the presented work on the notion of Concurrent Reactive Objects (CRO) and their abstraction into Reactive Components.In many cases, the execution platform puts firm resource limitations on available memory and speed of computations that must be taken into consideration for the validation of the system.In this paper, we focus on code synthesis from the model, and we show how specified timing requirements are preserved and translated into scheduling information. In particular, we present how ceiling levels for Stack Resources Policy (SRP) scheduling and analysis can be extracted from the model. Additionally, to support schedulability analysis, we detail algorithms that for a CRO model derives periods (minimum inter-arrival times) and offsets of tasks/jobs. Moreover, the design of a micro-kernel supporting cooperative hardware- and software-scheduling of CRO based systems under Deadline Monotonic SRP is presented.

  • 2.
    Kangas, Maarit
    et al.
    University of Oulu.
    Vikman, Irene
    Luleå University of Technology, Department of Health Sciences, Health and Rehabilitation.
    Wiklander, Jimmie
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Lindgren, Per
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Nyberg, Lars
    Luleå University of Technology, Department of Health Sciences, Health and Rehabilitation.
    Jämsä, Timo
    University of Oulu.
    Sensitivity and specificity of fall detection in people aged 40 years and over2009In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, ISSN 0966-6362, Vol. 29, no 4, p. 571-574Article in journal (Refereed)
    Abstract [en]

    About one third of home-dwelling people over 65 years of age fall each year. Falling, and the fear of falling, is one of the major health risks that affects the quality of life among older people, threatening their independent living. In our pilot study, we found that fall detection with a waist-worn triaxial accelerometer is reliable with quite simple detection algorithms. The aim of this study was to validate the data collection of a new fall detector prototype and to define the sensitivity and specificity of different fall detection algorithms with simulated falls from 20 middle-aged (40-65 years old) test subjects. Activities of daily living (ADL) performed by the middle-aged subjects, and also by 21 older people (aged 58-98 years) from a residential care unit, were used as a reference. The results showed that the hardware platform and algorithms used can discriminate various types of falls from ADL with a sensitivity of 97.5% and a specificity of 100%. This suggests that the present concept provides an effective method for automatic fall detection.

  • 3. Kangas, Maarit
    et al.
    Wiklander, Jimmie
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Wikman, Irene
    Nyberg, Lars
    Luleå University of Technology, Department of Health Sciences, Health and Rehab.
    Lindgren, Per
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Jämsä, Timo
    Sensorband fall detector prototype: validation through data collection and analysis2008In: 2nd International Symposium on Medical Information and Communications Technology: ISMICT'07. Proceedings, Oulu: University of Oulu, 2008Conference paper (Refereed)
  • 4.
    Lindgren, Per
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Eriksson, Johan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Aittamaa, Simon
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Pietrzak, Pawel
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Wiklander, Jimmie
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Scheduling of CRO systems under SPR-DM2011Conference paper (Refereed)
  • 5.
    Wiklander, Jimmie
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    A reactive approach to component-based design of resource-constrained embedded systems2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Embedded systems have become commonplace in today's society and the number of functions and their complexity are steadily increasing. This can be attributed to the advances in the microprocessor technology and the continuous development of more powerful and power-efficient microprocessors, which, in turn, allows more elaborate software implementations. Consequently, there is a strong interest in finding methods and tools that support flexible and efficient development of embedded software.Component-based design is an attractive approach for design of complex software systems. It reduces development time and cost and improves overall maintainability and robustness of the system. These benefits have been proven difficult to realize when designing software for embedded systems. In particular, it is a challange to manage the extra-functional properties of such systems (e.g. timing).This thesis presents a component-based software design methodology that enables constructing complex software for resource-constrained embedded systems, in particular systems with limited processing power and memory. The underlying component model is based on reactive objects, which are suitable for modeling embedded software. The component model along with the design methodology allows both functional and timing properties of a system model to be preserved during implementation process. Further, it enables the developer to offer platform-independent correctness for real-time systems, provided that the software can be scheduled on a given hardware platform.An effective use of the methodology requires tools supporting it. An integrated development environment (IDE), REKO, has been developed and is presented in this thesis. REKO supports constructing system models graphically and generating C code from the model for execution on bare metal. Using C code makes it easier to integrate REKO with existing tool chains used in industry. The thesis also includes a case study, in which REKO is used for designing a real-life system.The case study demonstrates the potential of the methodology to bridge the gap between state-of-the-art in component-based software design on the one hand, and the methods and tools currently used in the industry on the other.

  • 6.
    Wiklander, Jimmie
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Component-based software design of embedded real-time systems2009Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Embedded systems have become commonplace in today's society and their complexity and number of functions are steadily increasing. This can be attributed to the unceasing advances in the microprocessor technology and the continuous delivery of more powerful and power-efficient microprocessors, which, in turn, allows more elaborate software implementations. Consequently, there is a strong interest in finding methods and tools that support flexible and efficient development of embedded software. Since these qualities are typically attributed to component-based design it makes sense to develop new design techniques targeting embedded systems based on components. This thesis aims to adapt the traditional component-based design approach for development of embedded real-time software. Component-based design relies on the existence of consistent and coherent models of individual components that can be composed to model the whole system. However, it can be argued that the special characteristics of embedded systems make such modeling challenging. One reason is that embedded systems typically exhibit a strong integration between hardware and software, which leads to a need for a common design space, or at least the possibility to create consistent models of both hardware and software components of an embedded system. Another reason is that the majority of embedded systems can be viewed as real-time systems and therefore it is necessary to express timing requirements alongside functional properties in the model. In order to overcome these difficulties, we adopt a reactive perspective, in which the functionality of both hardware and software is described in terms of time-constrained reactions of reactive objects. This enables capturing the complete functionality of the system (hardware and software) along with timing requirements in a single model.The reactive view lies behind the modeling framework for embedded real-time systems and the component-based software design methodology presented in this thesis. The methodology allows both functional and timing properties of a system model to be preserved during implementation process by means of a seamless transition between a model and an implementation, whereas the modeling framework enables the developer to offer platform-independent correctness for real-time systems, provided that the software can be scheduled on a given hardware platform. Further, this thesis includes a case study, in which the methodology is used for designing a real-life system. The case study demonstrates the potential of the methodology to bring the benefits of classical component-based design to the realm of embedded systems.

  • 7.
    Wiklander, Jimmie
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Eliasson, Jens
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Kruglyak, Andrey
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Lindgren, Per
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Nordlander, Johan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Enabling component-based design for embedded real-time software2009In: Journal of Computers, ISSN 1796-203X, E-ISSN 1796-203X, Vol. 4, no 12, p. 1309-1321Article in journal (Refereed)
    Abstract [en]

    The increasing complexity of embedded software calls for a new, more efficient design approach. A natural choice is to use well-established component-based design; however, its adoption to design of embedded software has been slow and riddled with difficulties. It can be argued that these problems are due to the following peculiarities of embedded systems. Firstly, the tight integration between hardware and software, typical for embedded systems, makes it virtually impossible to model and implement software separately from hardware. Secondly, it is difficult to express timing requirements, an intrinsic part of functionality of many embedded systems, in dataflow abstractions traditionally used in component-based design. We propose to overcome these difficulties by introducing a uniform, consistent modeling of both hardware and software and by integrating timing requirements into the model. We present a modeling framework based on the notions of reactive objects and time-constrained reactions, which enables component-based design of embedded real-time systems. Within this framework, functionality of both hardware and software components is defined in terms of reactions to discrete external events, and timing requirements are specified for each reaction relative to the event that triggered it. We also present a detailed software design methodology for embedded real-time systems based on our modeling framework.

  • 8.
    Wiklander, Jimmie
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Eriksson, Johan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Lindgren, Per
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    An IDE for component-based design of embedded real-time software2011In: 6th IEEE International Symposium on Industrial Embedded Systems (SIES), Piscataway, NJ: IEEE Communications Society, 2011, p. 47-50Conference paper (Refereed)
    Abstract [en]

    This paper describes work in progress on a tool for component-based design of embedded real-time software. The tool supports graphical modeling of software systems using concurrent reactive objects and components, as well as generation of C code from the model. The resulting application code can then be combined with a lightweight kernel for execution on bare metal.

  • 9.
    Wiklander, Jimmie
    et al.
    Luleå tekniska univesitet.
    Eriksson, Johan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Lindgren, Per
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Utilizing an IDE for component-based design of embedded real-time software for an autonomous car2011Report (Other academic)
    Abstract [en]

    Embedded systems are inherently reactive and they often operate under resource and real-time constraints. Hence, a model supporting these fundamental properties is desirable for an efficient and correct design process. To this end, we have developed a component model and design methodology that enables component-based design of embedded software. Moreover, we have developed an Integrated Development Environment (IDE) that ensures a systematic development of software in accordance with the methodology.

    In this paper we review the IDE and it’s underlying modeling framework and demonstrate its applicability through a use-case with typical properties - a control system with real-time constraints and hardware interaction. This paper describes the whole design process – requirements specification, conceptual model, component-level design, component implementation, code synthesis, testing, and verification. In particular, we show how the modeling framework enforces a static component and communication structure reflecting the concurrent behavior of the system and its interaction with the environment (target platform).

    Our results (a working protoype) indicate applicability of the presented design approach, and show the IDE’s ability to generate efficient executables. Additionally, we show how to prove the schedulability of the target system in the IDE using standard scheduling theorems and machine assisted WCET measurements.

    In conclusion, this paper demonstrates both the applicability of the software design methodology and the functionality of the developed IDE.

  • 10.
    Wiklander, Jimmie
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Kruglyak, Andrey
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Nordlander, Johan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Lindgren, Per
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Personal alarm device: a case study in component-based design of embedded real-time software2011Conference paper (Other academic)
    Abstract [en]

    Designing software for embedded systems is complicated by such factors as the tight integration between software and hardware, scarceness of available resources, and hard real-time requirements. In our earlier work we proposed a component-based approach based on modeling both hardware and software using reactive objects and time-constrained reactions, which should allow us to overcome these difficulties. We also presented a software design methodology for embedded real-time systems.Here we describe a system developed using this methodology and discuss its advantages. The system is a personal alarm device that should be worn at the waist of a person and that should detect his or her fall and send an alarm signal. The implementation of the system was verified using a Simulink-based simulator. The simulation demonstrated that, even though calculation of acceleration was simplified to allow for an efficient execution on a resource-constrained platform, fall detection remained satisfactory.The case study demonstrates the advantages of the proposed software design methodology, including the fact that functional and timing properties of a system model can be preserved during implementation process by means of a seamless transition between a model and an implementation.

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