Enterprise Database Systems

Topics: Database transaction, Real-time computing, Database Pages: 63 (17962 words) Published: December 29, 2012
M¨ lardalen University Press Dissertations a No.21

Data Management in Vehicle Control-Systems
Dag Nystr¨ m o October 2005

Department of Computer Science and Electronics M¨ lardalen University a V¨ ster˚ s, Sweden a a

Copyright c Dag Nystr¨ m, 2005 o E-mail: dag.nystrom@mdh.se ISSN 1651-4238 ISBN 91-88834-97-2 Printed by Arkitektkopia, V¨ ster˚ s, Sweden a a Distribution: M¨ lardalen University Press a

As the complexity of vehicle control-systems increases, the amount of information that these systems are intended to handle also increases. This thesis provides concepts relating to real-time database management systems to be used in such control-systems. By integrating a real-time database management system into a vehicle control-system, data management on a higher level of abstraction can be achieved. Current database management concepts are not sufficient for use in vehicles, and new concepts are necessary. A case-study at Volvo Construction Equipment Components AB in Eskilstuna, Sweden presented in this thesis, together with a survey of existing database platforms confirms this. The thesis specifically addresses data access issues by introducing; (i) a data access method, denoted database pointers, which enables data in a real-time database management system to be accessed efficiently. Database pointers, which resemble regular pointers variables, permit individual data elements in the database to be directly pointed out, without risking a violation of the database integrity. (ii) two concurrency-control algorithms, denoted 2V-DBP and 2VDBP-SNAP which enable critical (hard real-time) and non-critical (soft realtime) data accesses to co-exist, without blocking of the hard real-time data accesses or risking unnecessary abortions of soft real-time data accesses. The thesis shows that 2V-DBP significantly outperforms a standard real-time concurrency control algorithm both with respect to lower response-times and minimized abortions. (iii) two concepts, denoted substitution and subscription queries that enable service- and diagnostics-tools to stimulate and monitor a control-system during run-time. The concepts presented in this thesis form a basis on which a data management concept suitable for embedded real-time systems, such as vehicle control-systems, can be built.

Swedish summary - Svensk sammanfattning
¨ Ett modernt fordon ar idag i princip helt styrt av inbyggda datorer. I takt ¨ med att funktionaliteten i fordonen okar, blir programvaran i dessa datorer ¨ mer och mer komplex. Komplex programvara ar sv˚ r och kostsam att kona struera. F¨ r att hantera denna komplexitet och underl¨ tta konstruktion, sato a sar nu industrin p˚ att finna metoder f¨ r att konstruera dessa system p˚ en a o a h¨ gre abstraktionsniv˚ . Dessa metoder syftar till att strukturera programvaran i o a dess olika funktionella best˚ ndsdelar, till exempel genom att anv¨ nda s˚ kallad a a a ¨ komponentbaserad programvaruutveckling. Men, dessa metoder ar inte effek¨ tiva vad g¨ ller att hantera den okande m¨ ngden information som f¨ ljer med a a o ¨ den okande funktionaliteten i systemen. Exempel p˚ information som skall a ¨ hanteras ar data fr˚ n sensorer utspridda i bilen (temperaturer, tryck, varvtal a osv.), styrdata fr˚ n f¨ raren (t.ex. rattutslag och gasp˚ drag), parameterdata, och a o a loggdata som anv¨ nds f¨ r servicediagnostik. Denna information kan klassas a o som s¨ kerhetskritisk eftersom den anv¨ nds f¨ r att styra beteendet av fordonet. a a o ¨ P˚ senare tid har dock m¨ ngden icke s¨ kerhetskritisk information okat, exema a a pelvis i bekv¨ mlighetssystem som multimedia-, navigations- och passagerara ergonomisystem. Denna avhandling syftar till att visa hur ett datahanteringssystem f¨ r inbygo gda system, till exempel fordonssystem, kan konstrueras. Genom att anv¨ nda a ett realtidsdatabashanteringssystem f¨ r att lyfta upp datahanteringen p˚ en h¨ go a o re abstraktionsniv˚ kan fordonssystem till˚ tas att hantera...
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