Object-oriented FrameWorks For On-board Satellite Software

Wolfgang Pree


The talk presents the results of a research project under way in the Software Research Lab of the University of Constance to apply object-oriented software framework technology to on-board space systems. The results discussed here were obtained in two separate activities: a study done for ESA-Estec and a research cooperation with Nokia In recent years, the framework approach has made software reuse a reality in many domains but it has so far been avoided in embedded systems in general and in space systems in particular because of concerns about its compatibility with real-time and safety constraints and because of constraints on memory and CPU resources on-board satellites. The application of framework technology to space software is being concretely investigated with the development of a software framework for the attitude and orbit control subsystem (AOCS) of satellites. The AOCS framework offers components that encapsulate in a reusable manner the following functionalities: telecommand handling, telemetry handling, failure detection, failure recovery, sequential data processing, sensor/actuator management, and sensor/actuator reconfiguration. The talk sketches the architecture of the AOCS framework and in particular shows how component reusability and mission-independence were achieved by separating the management of a functionality from its implementation. Mission-critical software must be developed according to rigorous procedures and formal processes. Such procedures and processes are well-established for traditional software technologies but remain a subject of investigation in the case of framework-based systems. At the University of Constance, the methodological aspects of software frameworks are being investigated in parallel to their technological aspects. A discussion of the results obtained so far in this area rounds out the talk.

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