Complete worst-case execution time analysis of straight-line hard real-time programs

Component-based development has proven effective in many engineering domains, and several general component technologies are available. Most of these are focused on providing an efficient software-engineering process. However for the majority of embedded systems, run-time efficiency and prediction of system behaviour are as important as process efficiency. This calls for specialized technologies. There is even a need for further specialized technologies adapted to different types of embedded systems, due to the heterogeneity of the domain and the close relation between the software and the often very application specific system. This work presents the SaveCCM component model, intended for embedded control applications in vehicular systems. SaveCCM is a simple model in which flexibility is limited to facilitate analysis of real-time and dependability. We present and motivate the model, and provide examples of its use.

/pdf/saveccm-a-component-model-for-safety-critical-real-time-2sbi5b6oey.pdf

SaveCCM - a component model for safety-critical real-time systems

https://www.es.mdh.se/pdf_publications/930.pdf

The SAVE approach to component-based development of vehicular systems

Methods for worst-case execution time (WCET) analysis have been known for some time, and recently commercial tools have emerged. This technique is gradually being entered into industry to analyse real production codes. This article presents a case study where the aiT WCET analysis tool was used to find upper time bounds for task-oriented vehicular control code. The main purpose was to investigate the practical difficulties that arise when applying the current WCET analysis methods to this particular kind of code. In particular, we were interested in how labor-intense the analysis becomes, measured by the number of manual annotations necessary for calculating a WCET estimate. We were also interested how much tighter WCET estimates will become by manually adding extra annotations, and how much additional work that is needed to give these annotations. We also made some systematic comparisons between calculated and measured WCET estimates for the analysed system.

/pdf/static-wcet-analysis-of-real-time-task-oriented-code-in-37zetg5ecv.pdf

Static WCET Analysis of Real-Time Task-Oriented Code in Vehicle Control Systems

This paper presents a new conceptual model, the XBW-model. Distributed computing is becoming a cost effective way to implement safety critical control systems. To support the development of such systems the XBW conceptual model was developed. The model describes the time behavior and distribution properties of a system in such a way that static scheduling and systematic fault tolerance can be applied. The conceptual model also enables the definition of an appropriate fault model. This fault model along with the XBW-model allow efficient and systematic use of well known software based error detection methods. A distributed steer-by-wire control system is described, which is developed according to the model. The XBW-model is developed within in the European Brite-EuRam III project X-By-Wire.

The XBW model for dependable real-time systems

BASEMENT/sup TM/ is a distributed real-time architecture developed for vehicle internal use in the automotive industry. BASEMENT covers application development, as well as the hardware and software that provide execution and communication support. This paper gives an overview of the BASEMENT concept, as well as presenting two system realizations. The first realization is based on the commercial real-time kernel Rubus, while the second is an ultra-dependable architecture (DACAPO) with provisions for fault tolerance at various system levels. BASEMENT is designed for the automotive systems of the future. These systems will be required to simultaneously handle multiple safety critical functions and a large number of less critical functions. All of these features are to be provided at a production cost substantially lower than that of current systems, and, at the same time, with a reliability allowing vehicles to be built without mechanical backup systems, even for safety critical subsystems such as braking and steering.

/pdf/basement-an-architecture-and-methodology-for-distributed-189ml2chs9.pdf

O. Bridal

Papers

BASEMENT: an architecture and methodology for distributed automotive real-time systems