Enhancing fault tolerance of autonomous mobile robots

• 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.

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 robot’s 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.