Robotic systems evolving in hazardous and harsh environment are prone to mission failure or system loss in presence of faults. This paper presents a fault tolerant methodology, implemented into a control architecture of an underwater robot that executes biological monitoring missions. High level constraint violations (mission, safety, energy, time and localization) and low level faults (software and hardware faults) are considered using a method based on fault trees. These undesirable events are detected and treated by a fault tolerant module that decides to recover at low level or to give a feedback to the mission manager which selects the high level reaction. This fault tolerant architecture has been tested on real field conditions, and we illustrate our methodology on a set of selected events. We conclude about reliability improvement of low cost underwater robots for complex and long missions.

This paper presents a global methodology developed to increase the reliability of mobile robots. An initial analysis of robot functions and their corresponding significant failures enabled us to introduce dedicated observation modules in the embedded architecture to monitor fault events. Once detected, the functioning mode of the robot can be adapted according to the failure severity level to ensure the success of its mission. The methodology was applied in a case study and the experimental implementation and results are detailed.

This paper aims to model workflow processes and to analyze them. From an enterprise model, we automatically translate the workflow processes into an equivalent Petri net which allows to check properties of good behavior. Thus, it is possible to verify the good modeling and to detect some process problems in the enterprise.

To analyze the behavior of Petri nets, the reachability graph permits us to verify qualitative properties. However, even for small nets, the reachability graph can become infinite if the studied Petri net is unbounded. So, to deal with the state space explosion problem, the coverability graph must be used. The paper aims to expose the main ways of construction of coverability graphs and specifies how some qualitative properties can be checked in these different approaches.

Managers need to model and analyze the enterprise processes from different points of view in order to measure their efficiency. The paper focuses on an enterprise modeling approach allowing us to describe and analyze the influence of an activity in a process. The modeling method is based on the definition of a set of criteria related to the user's efficiency estimators. The analysis is decomposed into three levels allowing us to qualify qualitatively and quantitatively the studied process.

A high testability measure based on constraints propagation and dedicated to deterministic test of the combinational part of scannable circuits is compared to three others high level testability measures of the literature. This measure is used to guide hierarchical generation of test vectors and automatic test point insertion.>