Fault Tolerance in Autonomous Systems: How and How Much?

Autonomous systems are starting to appear in space exploration , elderly care and domestic service; they are particularly attractive for such applications because their advanced decisional mechanisms allow them to execute complex missions in uncertain environments. However, systems embedding such mechanisms simultaneously raise new concerns regarding their dependability. We aim in this paper to present these concerns and suggest possible ways to resolve them. We address dependability as a whole, but focus specifically on fault tolerance. We present some particularities of autonomous systems and discuss the dependability mechanisms that are currently employed. We then concentrate on the dependability concerns raised by decisional mechanisms and consider the introduction and assessment of appropriate fault tolerance mechanisms.