Some studies on Control of Autonomous Underwater Vehicles

Abstract

In the recent years, increasing the autonomy of the underwater vehicles is an important newlineelement in order to deal with highly hazardous and unknown ocean environment. newlineNowadays, autonomous underwater vehicles (AUVs) are mostly preferred for underwater newlineintervention tasks in opposed to remotely operated vehicles (ROVs) to avoid newlineoperator fatigue and ensure their safety. Mostly the underwater intervention tasks involved newlinedeep sea pipelines survey and tracking, explorations of the ocean resources, newlineoceanographic mapping etc. In these applications, the accurate position and attitude newlinecontrol of an AUV is highly desirable to acquire good quality of data since this is highly newlinedependent on the accuracy of the station keeping and position tracking of the AUV. newlineHowever, to achieve accurate trajectory tracking control of an AUV is very difficult due newlineto unstructured nature of underwater environment and vehicle dynamics is highly nonlinear, newlinecoupled and time-varying. In addition to these, variations in the hydrodynamic newlinecoefficients with different operating conditions and vehicle may subject to unknown newlineforces such as ocean currents which makes trajectory tracking control design even more newlinecomplicated. Thus, it is highly desirable to have dedicated AUV tracking control system newlinewhich has capability to cope up with uncertain nature of the ocean environment. newlineFor deep-sea autonomous nontrivial underwater tasks, particularly those are inaccessible newlineto humans require a manipulator arm mounted on the underwater vehicle, refereed newlineas Autonomous underwater vehicle-manipulator system (AUVMS). However, position newlinecontrol of AUVMS becomes even more difficult because of increased non-linearity, newlinestrong coupling between manipulator and AUV, and resulting high dimensional nature. newlineAlso due to attached manipulator arm, AUVMS becomes a kinematically redundant newlinestructure, requiring redundancy resolution schemes to handle the situation. To avoid newlineredundancy resolution problem, the task-space based control scheme designs have been newlinesuggested in this work. The main ad