Retour au site du LAAS-CNRS

Abstract

Robotic systems have to carry out more and more complex tasks, including ones where humans can be endangered. Residual design faults in such systems, as well as the inevitability of physical faults and interac- tion faults during operation, motivate the use of safety monitors to prevent catastrophic failures. In this paper, we consider the design of such safety monitors for multi- functional robotic systems. We present an approach and a formalization of the process for determining safety rules. It consists in identifying safety modes, according to the different tasks carried out by the monitored system. In practice, each safety mode is related to one or several functional modes and is speci
ed by a permissiveness vector that de
nes the authorized domains of variation of key physical variables. The set of safety modes can be partially ordered according to their authorization vectors and can thus be represented as a directed acyclic graph. This graph is used to automatically build a model representing safety modes and their transitions, which can be implemented in an independent safety monitor. A case study has been carried out on a mobile manipulator robot, working in a factory alongside humans.

Mots-Clés / Keywords

Mots-Clés / Keywords

Abstract

Autonomous robots offer alluring perspectives in numerous application domains: space rovers, satellites, medical assistants, tour guides, etc. However, a severe lack of trust in their dependability greatly reduces their possible usage. In particular, autonomous systems make extensive use of decisional mechanisms that are able to take complex and adaptative decisions, but are very hard to validate. This paper proposes a fault tolerance approach for decisional planning components, which are almost mandatory in complex autonomous systems. The proposed mechanisms focus on development faults in planning models and heuristics, through the use of diversification. The paper presents an implementation of these mechanisms on an existing autonomous robot architecture, and evaluates their impact on performance and reliability through the use of fault injection.

Abstract

Mobile devices (e.g., laptops, PDAs, cell phones) are increasingly relied on but are used in contexts that put them at risk of physical damage, loss or theft. This paper discusses security considerations that arise in the design of a cooperative backup service for mobile devices. Participating devices leverage encounters with other devices to temporarily replicate critical data. Anyone is free to participate in the cooperative service, without requiring any prior trust relationship with other participants. In this paper, we identify security threats relevant in this context as well as possible solutions and discuss how they map to low-level security requirements related to identity and trust establishment. We propose self-organized, policy-neutral mechanisms that allow the secure designation and identification of participating devices. We show that they can serve as a building block for a wide range of cooperation policies that address most of the security threats we are concerned with. We conclude on future directions.

Mots-Clés / Keywords