  Based on the need for high resolution underwater visual surveys, this study
presents the adaptation of an existing SPARUS II autonomous underwater vehicle
(AUV) into an entirely hovering AUV fully capable of performing autonomous,
close range imaging survey missions. This paper focuses on the enhancement of
the AUVs maneuvering capability (enabling improved maneuvering control),
implementation of an state of the art thruster allocation algorithm (allowing
optimal thrusters allocation and thrusters redundancy), and the development of
an upgraded path following controller to facilitate precise and delicate
motions necessary for high resolution imaging missions. To facilitate the
vehicles adaptation, a dynamic model is developed. The calibration process of
the dynamic model coefficients initially obtained using well accepted formulas,
by computational fluid dynamics and in real sea experiments is presented. The
in house development of a pressure resistant imaging system is also presented.
This system which includes a stereo camera and high power lightning strobes was
developed and fitted as a dedicated AUV payload. Finally, the performance of
the platform is demonstrated in an actual seabed visual survey mission.
