AUV controllability with control plane faults

It may be important to be able to operate an autonomous underwater vehicle (AUV) when it has reduced control authority due to a control plane fault, such as a jammed or a missing control plane. Knowledge of how the vehicle behaves under these conditions will allow the mission planner to make critical decisions about the viability of the mission or about certain specific subtasks. Knowledge of vehicle behaviours under fault conditions can also facilitate the use of operational envelopes in restricted waters; i.e. a healthy AUV may be restricted in the magnitude of control plane deflections, so that it can maintain a safe trajectory even if a control plane fails. A systematic study was made involving simulations of the vehicle under fault conditions to identify the vehicle behaviours typical of such fault conditions. The simulation tool used is a linear model developed from a fully nonlinear model of the Canadian Self-Contained Off-theshelf Underwater Testbed (C-SCOUT), and the manoeuvres used were those most likely to be desired during normal operation: holding course, a controlled dive, and a turn in the horizontal plane. The fault condition simulations provide useful information, especially concerning safe operating envelopes for the CSCOUT for particular mission requirements. The information can also be used to enable the vehicle to perform selfdiagnosis procedures under some conditions.NRC publication: Ye