Karen Godary-Dejean

Enhancing fault tolerance of autonomous mobile robots

Experience demonstrates that autonomous mobile robots running in the field in a dynamic environment often breakdown. Generally, mobile robots are not designed to efficiently manage faulty or unforeseen situations. Even if some research studies exist, there is a lack of a global approach that really integrates dependability and particularly fault tolerance into the mobile robot design.This paper presents an approach that aims to integrate fault tolerance principles into the design of a robot real-time control architecture. A failure mode analysis is firstly conducted to identify and characterize the most relevant faults. Then the fault detection and diagnosis mechanisms are explained. Fault detection is based on dedicated software components scanning faulty behaviors. Diagnosis is based on the residual principle and signature analysis to identify faulty software or hardware components and faulty behaviors. Finally, the recovery mechanism, based on the modality principle, proposes to adapt the robots control loop according to the context and current operational functions of the robot.This approach has been applied and implemented in the control architecture of a Pioneer 3DX mobile robot. Autonomous mobile robotics fails to carry out complex mission in dynamic environment.Presentation of a global fault tolerant methodology enhancing robots dependability.FMECA fault forecasting and failure detection using dedicated software modules.Diagnosis based on signature analysis and recovery using autonomy level adaptation.Implementation and experiments of these concepts in a real-time control architecture.

Handling Exceptions in Petri Net-Based Digital Architecture: From Formalism to Implementation on FPGAs

A component-based approach to the specification and implementation of complex digital systems on field-programmable gate arrays (FPGAs) has been developed, with the behavior and composition of the components specified by Petri nets (PNs). Yet modeling behavior in the case of error becomes intricate if only PNs are used. In this case, the designer often has to address every possible situation when an error occurs, which leads to complex models and human errors. This paper offers a way to model exception handling by adding the concept of macroplace (MP) to the formalism while preserving the conformity and efficiency of the implementation on a programmable logic device (such as FPGAs), as well as the analyzability of the model.

Fault tolerance enhancement using autonomy adaptation for autonomous mobile robots

This paper presents how autonomy adaptation can be useful to enhance the fault tolerance of autonomous mobile robots. For that, we proposed a global and structured methodology which allows integrating specific fault tolerant mechanisms into an adaptive control architecture. When a problem is detected, the autonomous behavior of the robot is automatically adapted to overcome it. The human operator can punctually or definitively be inserted in the control loop to replace the damaged functionalities and to ensure the success of the mission. Experimental results on a mobile robot are proposed to illustrate the autonomy adaptation.

Toward Performance Guarantee for Autonomous Mobile Robotic Mission: An Approach for Hardware and Software Resources Management

Mission performance is a large concept. It is rarely addressed in the context of autonomous mobile robotics. This paper proposes a generic framework addressing the concept of performance for autonomous mobile robotic mission. Moreover it presents an approach to manage the mobile robot hardware and software resources during the mission execution according to performance objectives. Simulation results illustrate the proposed approach on a patrolling mission example.

Automatic Handling of Conflicts in Synchronous Interpreted Time Petri Nets Implementation

Several solutions for implementing Petri net models on FPGA thanks to a transformation in a VHDL code have been proposed in literature. But none deals with the management of transition conflicts in the specific case of synchronous implementation of interpreted Petri nets. This article presents an automatic method to deal with conflicts from their detection to their implementation on FPGA. One solution for binary Petri nets is proposed. For the generalized case, two solutions are proposed and experimentally compared. Thus a solution is provided for the implementation of interpreted generalized time Petri nets.

Formal Method for Mission Controller Generation of a Mobile Robot

This article presents a methodology for generating a real-time mission controller of a submarine robot. The initial description of the mission considers the granularity constraints associated with the actors defining the mission. This methodology incorporates a formal analysis of the different possibilities for success of the mission from the models of each component involved in the description of the mission. This article ends illustrating this methodology with the generation of a real robotic mission for marine biodiversity assessment.

Fault tolerant autonomous robots using mission performance guided resources allocation

Real long-term, complex and autonomous mission is still a challenge for robotics. This paper presents an efficient approach enhancing the robot with fault tolerance. It uses performance viewpoints to guide hardware and software resources allocation all along the mission according to faults effects and detection. Simulated and experimental results are proposed and analyzed.