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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.

Mots-Clés / Keywords

Abstract

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.

Mots-Clés / Keywords

Abstract

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.