AUV MOTION CONTROL FOR RECOVERY ON THE ROUTE TRAJECTORY IN THE OCCURRENCE OF FAILURES

Abstract

The aim of the research is to return the autonomous underwater vehicle to the route trajectory
as soon as possible after the observation in the event of failures in the actuators that ensure
the movement of the vehicle. The need to solve the problem is due to the fact that when the device
overcomes distances of several thousand kilometers, its position deviates from the route trajectory due to the accumulation of the error in the reckoning of coordinates by the onboard inertial navigation
system. As a result, the apparatus is forced to return to the route trajectory, during which a
failure may occur in the actuators that ensure the movement of the apparatus. Previously, the
problem was not considered in this formulation, and the approaches used in similar situations to
unmanned aerial vehicles turned out to be unsuitable. The most typical reasons that distinguish an
underwater vehicle from a drone are: the difference in the reasons for deviation from the route
trajectory (inertial system for the device and the wind for the drone), lack of navigation using signals
from satellite radio navigation systems and the inability to control its location when returning
to the route , low maneuverability of the device in comparison with the drone. To solve the problem
of ensuring the movement of the apparatus to the route trajectory in the event of a failure of
the executive device, which ensures the movement of the apparatus, it is proposed to choose an
alternative one from the number of redundant ones instead of the failed one. The choice of a backup
device is determined, first of all, by the moment created by the device for maneuvering the apparatus
along the course. At the same time, it is shown that, in view of the limitations on the ability
of the backup device to provide the apparatus with the required maneuver along the course, it is
also necessary to choose the trajectory of the apparatus when returning to the route trajectory.
For this, five possible return methods were analyzed, differing in the dynamics of the course
change, the length of the path, and the duration of maneuvering. Taking into account the smoothness
of the course change for each trajectory, the most suitable actuators were determined, capable
of ensuring the movement of the apparatus along the selected trajectory. The main criterion
when choosing a trajectory, along with taking into account the limitations, was to minimize the
distance traveled to the route trajectory in order to save the energy resource of the apparatus.
After the selection of the actuator and the trajectory of the apparatus for restoration on the route
trajectory, a sequence of calculations is presented to determine the parameters of the actuator at
each moment of time throughout the return of the apparatus to the route trajectory. The results of
the research made it possible to solve the problem of restoring the position of an autonomous underwater
vehicle on the route trajectory in the shortest possible time in the event of a failure in the
executive devices that ensure its movement.