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MAROFF-2-Maritim virksomhet og offsh-2

Feasibility study of a concept for operating remotely controlled underwater vehicles from an unmanned surface vessel.

Alternative title: Forstudie av en konseptløsning for operasjon av fjernstyrte undervannsfartøy fra et ubemannet overflatefartøy.

Awarded: NOK 2.7 mill.

The project?s objective is to establish a concept for operation of remotely operated vehicles from an unmanned surface vessel, and to demonstrate the feasibility of such concept. An affirmative outcome may serve as basis for further development and industrialization of the concept. Underwater remotely operated vehicles (ROV?s) are among the essential tools for seabed surveys and installation and -maintenance of subsea installations within the oil & gas industry, and increasingly also within aquaculture and offshore renewables. ROVs are highly manoeuvrable, and able to operate a wide range of tools and instruments. ROVs are normally operated from a manned surface vessel, with which it is connected via an umbilical for power supply and exchange of data and -control signals. The surface vessels are often large, multi-functional offshore vessels. As a result, the current cost of ROV operations primarily relate to the surface vessel and its crew, and to a lesser extent to the ROV and its operators. Moreover, the ROV operators are required to stay aboard the vessel even if the ROV is only occasionally used, which further adds to the cost. For many ROV duties where a multi-functional offshore vessel does not add value, notable savings could hence be made if ROVs could instead be operated from an unmanned, small and single-purpose vessel, and where the ROV would be controlled remotely by operators at an onshore control centre as and when required, and where the operators may commonly control multiple ROVs. The latter becomes further relevant as ROVs are anticipated to increasingly operate autonomously, and only occasionally require manual control. The key challenges to be addressed in the project relate to the following: 1) Motions and motion reduction for small vessels; 2) Launch and recovery of ROV from/to small vessels more prone to motions; 3) Offshore communications for effective monitoring- and remote control of ROV and surface vessel. The project has progressed largely according to plan. A monohull baseline concept has been developed and operability analysis performed, calculating vessel motions and moonpool responses. Preliminary findings are that the relative influence of viscous components on motions is notable for this size of vessel. For this reason, further resources than initially foreseen have been devoted to creating a more comprehensive vessel motions model to properly account for such influence, whereas somewhat less resources have been devoted to exploring additional concepts (i.e. quality has been opted for over quantity). However, an alternative SWATH hull concept has also been developed and motion and response analysis concluded. The motions model preparation was accelerated in order to firm up the basis for a Phase 2 application, which among several objectives served to determine coefficients representing the viscous component, thus serving to calibrate the motions model, as well as capture phenomena that might not be captured in an analytical motions model. A review of state-of-the-art DP has been conducted to identify technologies relevant for more dynamic states, as will be relevant for smaller vessels. Extensions of conventional dynamic positioning (DP) control algorithms that compensate for oscillatory wave motions have been analyzed in three NTNU master theses. This work has been continued in NTNU student projects, where a multi-body simulator of the surface vessel, the launch and recovery system, and the ROV has been built. The findings show that successful DP algorithms for dynamic first order wave motion reduction include acceleration feedback, optimal control, roll damping, and feed-forward using short-term wave prediction in order to partially compensate for thruster dynamics. A concept for new ROV Launch and Recovery System for small vessels prone to motions has been designed and further developed based on the research results. Prospective means of low latency communications research have been completed, focusing on analysing the user requirements for data rates, quality and latencies. Currently available technologies and services for communication has been studied, as well as technologies and services that are expected to be available in the future. This has focused on ship-to-ship, ship-to-platform and ship-to-shore radio communication in combination with fiber optics from fixed installations. It has included the concept of communication relays installed on small fully autonomous surface vessel, and also new expected services using low-earth orbit satellites. The final stage of Phase 1 has been focusing on final reporting and the project phase is now concluded. The project will be continued in Phase 2, that started late 2020.

The primary results achieved reflect increased and largely new knowledge within the domain of rapid-acting DP systems. This is a field that has received little research previously but which may be significant for the effective operation of small craft (such as USVs). Cost studies performed for the tentative embodiment of the ROV Revolution concept (Vessel plus ROV) considering CAPEX, OPEX and VOYEX, have indicated that the ROV Revolution concept provides for a cost reduction of abt. 45% vs. small size manned survey vessels, and abt. 70% reduction from medium size subsea IMR vessels. The emission reduction is even more significant, at abt. 60% and 80% respectively. A tangible utility value from an industrial perspective for KM, is that the increasing knowledge base resulting from the ROV Revolution project, has contributed to prospective pilot customer Reach Subsea opting to engage in cooperation with KM, with the ambition to industrialize the ROV Revolution project.

Due to superior performance and versatility, work-class ROVs are – and are likely to remain – the workhorse of subsea construction and IMR within oil & gas and renewables. ROVs are today primarily operated- and controlled from large, manned, multi-functional subsea vessels. However, for many ROV duties, there is limited- or no value added from the extensive capabilities of such vessels. On the contrary, the current means of operation drives costs and restricts productivity. The project seeks to explore a concept for operating ROVs from a small-scale, un-manned, self-propelled, remote or autonomous controlled mother vessel (named the ROV Revolution). If and when the mother vessel and/or ROV does not operate autonomously, either may be controlled from a manned control centre, either ashore or aboard another fixed or floating asset. This project seeks to demonstrate the commercial viability and technical feasibility of such concept. If successful, such concept could radically reduce costs and enhance productivity of ROV operations, thereby lowering the cost of offshore oil & gas, and enhancing the competitiveness of offshore renewables. Concept feasibility will largely depend on resolving the following principal R&D challenges: - Establish relevant means for motion reduction and motion control of small vessels, notably focusing on relative motions between vessel and ROV; - Establish relevant means for ROV launch and recovery from small vessels prone to rapid and extensive motions; - Establish relevant means for low latency offshore communications for effective real-time remote ROV control.

Funding scheme:

MAROFF-2-Maritim virksomhet og offsh-2