On attitude observers and inertial navigation for reference system fault detection and isolation in dynamic positioning

Marine craft employing a dynamic positioning system rely on measurements from position reference systems and gyrocompasses, and faults in these systems and sensors pose a serious risk of vessel drive-offs, that may in turn have dire consequences. An inertial measurement unit may provide independent position and orientation information, provided that the attitude estimates of the observer in use are accurate enough. In this paper we compare three nonlinear strapdown inertial-measurement-unit-based attitude estimators aided by global navigation satellite systems, and put them to test in a simulation of two fault detection and isolation scenarios. The comparison finds that all attitude estimators under test have the potential for use in a fault detection and isolation scheme.