A hybrid remotely operated underwater vehicle for maintenance operations in aquaculture: Practical insights from Greek fish farms

• HROV design encompassing both autonomous and remotely operated features. • Enhancing aquaculture maintenance operations using underwater systems. • Design and applications of underwater systems for aquaculture. • Operational effectiveness of the HROV by field trials in Greek fish farm. • Subaquatic manipulator attached to perform maintenance tasks. Aquaculture serves a pivotal function in catering to the increasing global need for seafood while simultaneously tackling the predicaments posed by the dwindling wild fish reserves. Underwater vehicles have contributed to the expansion of aquaculture by enabling underwater inspections, data collection, and improved maintenance procedures. In addition, underwater vehicles facilitate the acquisition of subsea data, enabling researchers to enhance aquaculture procedures and participate in initiatives aimed at attaining food security. The aim of this work is to design, develop, and evaluate underwater systems for the inspection and maintenance of net cages in aquaculture facilities. The research focuses on developing an underwater vehicle for aquaculture inspection along with the integration of a manipulator to perform maintenance tasks such as removing objects stuck on nets, collecting fish morts, and repairing net tears. This paper provides thorough research on the design of these systems and their applications in aquaculture in Greece. The subsequent focus is directed towards the development of a hybrid remotely operated vehicle, accentuating its software frameworks, modeling, mobility implementation, and navigational capabilities. This system can operate as a tetherless autonomous underwater vehicle for inspection tasks and as a tethered remotely operated vehicle with semi-automatic capabilities for maintenance tasks. In light of this, a tool manipulator is introduced, analyzing its underlying design principles, manipulator capabilities, and electronic integration. The effectiveness and operational capabilities of the underwater vehicle models are substantiated through experimental assessments carried out in Kefalonia fish farms in Greece, resulting in successful missions. The final remarks encapsulate the principal findings obtained from this study, examine their implications, and offer perspectives on forthcoming avenues for subaquatic robotics.