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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 diversi ication. 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.

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Abstract

Autonomous robots make extensive use of decisional mechanisms, such as planning. These mechanisms are able to take complex and adaptative decisions, but are notoriously hard to validate. This paper reports an investigation of how redundant, diversi ied models can be used to tolerate residual design faults in such mechanisms. A fault-tolerant temporal planner has been designed and implemented using diversity, and its effectiveness demonstrated experimentally through fault injection. The pa- per describes the implementation of the fault-tolerant planner and discusses the results obtained. The results indicate that diversi ication provides a noticeable improvement in planning reliability with a negligible performance overhead. However, further improvements in reliability will require implementation of a on-line checking mechanism for assessing plan validity before execution.

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SESAME (Software Environment for Software Analysis by Mutation Effects) is a fault injection tool using mutation as the target fault model. It has been used for 15 years to support dependability research at LAAS-CNRS. A salient feature of SESAME is that it is multi-language. This made it possible to inject faults into software written in assembly languages, procedural languages (Pascal, C), a data-flow language (LUSTRE), as well as in a declarative language for temporal planning in robotics. This paper provides an overview of the tool, and reports on its use in experimental research addressing either fault removal or fault tolerance topics.

Abstract

Mobile devices are increasingly relied on but are used in contexts that put them at risk of physical damage, loss or theft. We consider a fault-tolerance approach that exploits spontaneous interactions to implement a collaborative backup service. We deine the constraints implied by the mobile environment, analyze how they translate into the storage layer of such a backup system and examine various design options. The paper concludes with a presentation of our prototype implementation of the storage layer, an evaluation of the impact of several compression methods, and directions for future work.

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In the immediate future, metrics related to safety and dependability have to be found in order to successfully introduce robots in everyday environments. The crucial issues needed to tackle the problem of a safe and dependable physical human-robot interaction (pHRI) were addressed in the EURON Perspective Research Project PHRIDOM (Physical Human- Robot Interaction in Anthropic Domains), aimed at charting the new territory of pHRI. While there are certainly also cognitive issues involved, due to the human perception of the robot (and vice versa), and other objective metrics related to fault detection and isolation, the discussion in this paper will focus on the peculiar aspects of physical interaction with robots. In particular, safety and dependability will be the underlying evaluation criteria for mechanical design, actuation, and control architectures. Mechanical and control issues will be discussed with emphasis on techniques that provide safety in an intrinsic way or by means of control components. Attention will be devoted to dependability, mainly related to sensors, control architectures, and fault handling and tolerance. After PHRIDOM, a novel research project has been launched under the Information Society Technologies Sixth Framework Programme of the European Commission. This Specific Targeted Research or Innovation project is dedicated to Physical Human-Robot Interaction: depENDability and Safety (PHRIENDS). PHRIENDS is about developing key components of the next generation of robots, including industrial robots and assist devices, designed to share the environment and to physically interact with people. The philosophy of the project proposes an integrated approach to the co-design of robots for safe physical interaction with humans, which revolutionizes the classical approach for designing industrial robots  rigid design for accuracy, active control for safety  by creating a new paradigm: design robots that are intrinsically safe, and control them to deliver performance. This paper presents the state of the art in the field as surveyed by the PHRIDOM project, as well as it enlightens a number of challenges that will be undertaken within the PHRIENDS project.

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The pervasive interconnection of systems throughout the world has given computer services a significant socioeconomic value that both accidental faults and malicious activity can affect. The classical approach to security has mostly consisted of trying to prevent bad things from happening--by developing systems without vulnerabilities, for example, or by detecting attacks and intrusions and deploying ad hoc countermeasures before any part of the system is damaged. But what if we could address both faults and attacks in a seamless manner, through a common approach to security and dependability?

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