2020-12-08 09:57:23 +00:00
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2020-12-16 16:41:24 +00:00
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2020-12-08 09:57:23 +00:00
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\pdf_title "Net-zero Cable Repair Ship"
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2020-12-08 09:57:23 +00:00
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\pdf_author "Andy Pack"
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2020-12-16 16:41:24 +00:00
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2020-12-08 09:57:23 +00:00
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\end_layout
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\begin_layout Right Footer
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Andy Pack
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\end_layout
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\begin_layout Left Footer
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January 2021
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\end_layout
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\begin_layout Left Header
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Sustainable Cable Ship - Group 1
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\end_layout
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2020-12-08 10:06:25 +00:00
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\begin_layout Part
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Vessel Study
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\end_layout
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\begin_layout Section
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Propulsion
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\end_layout
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\begin_layout Subsection
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Power Requirements
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\end_layout
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\begin_layout Subsubsection
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Hotel Load [AP]
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\end_layout
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2020-12-08 09:57:23 +00:00
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\begin_layout Section
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2020-12-08 10:06:25 +00:00
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Efficiency Investigations
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\end_layout
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\begin_layout Subsection
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Solar [AP]
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\end_layout
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\begin_layout Section
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Energy Storage [AP]
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\end_layout
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\begin_layout Subsection
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Battery Chemistry
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\end_layout
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\begin_layout Subsection
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Time-dependent Modelling
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\end_layout
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\begin_layout Section
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Mission Ops
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\end_layout
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2020-12-16 16:41:24 +00:00
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\begin_layout Subsection
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Grapnel-based Operations [AP]
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\end_layout
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\begin_layout Standard
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While the use of robotics has made sub-sea cable repair operations more
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efficient, durable and accurate, as will be discussed there are situations
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where this is not available and it is worth briefly outlining how grapnels
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are used in repair operations.
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\end_layout
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\begin_layout Standard
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Grapnels are specialised tools attached to lengths of chain which trail
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the stern of the ship.
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For cable repair operations, a cut & hold grapnel is used
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\begin_inset CommandInset citation
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key "cut-and-hold-paper,cut-and-hold-eta-product"
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literal "false"
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\end_inset
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.
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With knowledge of the path of the subject cable and the location of the
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fault, the grapnel is lowered before the boat makes a pass perpendicular
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to the cable.
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As the grapnel makes contact it is able to both cut and grip the cable
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before being raised to the surface vessel.
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\begin_inset Flex TODO Note (Margin)
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status open
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Disadvantages
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\end_layout
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\end_inset
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\end_layout
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2020-12-08 10:06:25 +00:00
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\begin_layout Subsection
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2020-12-14 20:24:08 +00:00
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Unmanned Underwater Vehicle Operations [AP]
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\end_layout
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\begin_layout Standard
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The following section outlines how the use of an unmanned underwater vehicle
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(UUV) can make mission operations more efficient and precise.
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The state of current UUV usage throughout cable repair operations is outlined
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in order to identify the critical capabilities and requirements.
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2020-12-18 17:56:59 +00:00
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The future of the domain is then explored and the challenges in applying
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these developments to sub-sea cable repair are identified before exploring
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how these can be overcome in order to meet the determined requirements.
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2020-12-14 20:24:08 +00:00
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Prior to this, the domain of UUVs as a whole is described in order to outline
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the scope of available vehicles.
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\begin_inset Flex TODO Note (Margin)
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Why ROVS?
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\end_layout
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\end_inset
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2020-12-14 20:24:08 +00:00
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\end_layout
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\begin_layout Subsubsection
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2020-12-16 16:41:24 +00:00
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UUV Classes
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\end_layout
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\begin_layout Paragraph
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ROVs and AUVs
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\end_layout
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2020-12-16 16:41:24 +00:00
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\begin_layout Standard
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UUVs are generally divided into two categories, remotely operated underwater
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vehicles (ROV) and autonomous underwater vehicles (AUV) with the distinction
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being between whether a human is controlling the vehicle or whether it
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operates independently; as such they have different applications.
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ROVs have been the vehicle class of choice where intervention and actuation
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is required such as offshore oil and gas operations and cable repair.
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A human operator controls the vehicle from the surface vessel, bi-directional
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communication including data, control, video and power are transmitted
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through an umbilical cord tether between the two vessels.
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AUVs on the other hand have primarily been used for survey and research
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purposes.
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\begin_inset Flex TODO Note (Margin)
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status open
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\begin_layout Plain Layout
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No umbilical cord?
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\end_layout
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\begin_layout Standard
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This distinction in responsibilities is not static, however.
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Like other robotics domains such as auto-mobiles and ships, autonomy is
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a rapidly developing area of research and development and newer vehicles
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are able to complete many more complex operations without human intervention
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and with longer endurance.
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\end_layout
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\begin_layout Paragraph
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Physical Configuration
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\end_layout
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\begin_layout Standard
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The physical layout of a UUV can generally be described by one of two classes,
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box frames or torpedo shaped.
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\begin_inset Flex TODO Note (Margin)
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status open
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\begin_layout Plain Layout
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determined by the size and range of the vehicle.
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\end_layout
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\end_inset
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Box frame UUVs are typically larger with more space for instruments and
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actuators but are not expected to make longer distance journeys as a result
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of their poor hydrodynamic profile.
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Torpedo shaped vehicles tend to be smaller without actuators; their hydrodynami
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c profile makes them well suited for faster, longer distance missions however
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this comes at the cost of reduced stability and control.
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\end_layout
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2020-12-14 20:24:08 +00:00
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\begin_layout Subsubsection
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Current ROV Usage
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\end_layout
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2020-12-16 16:41:24 +00:00
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\begin_layout Standard
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Cable repair operations are currently undertaken, where possible, with human-con
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trolled ROVs.
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With visual contact and direct actuation at the seabed, the ROV is used
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to identify, cut and grip the cable for retrieval to the surface-vessel.
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In doing so the need for repeated motions of the ship across the cable
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is removed, saving time and fuel.
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Instead the surface vessel uses dynamic positioning in order to maintain
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it's position above the ROV and cable.
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\end_layout
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\begin_layout Standard
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While this finer control is a key benefit for ROV use over grapnels, one
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of the most important benefits is the ability to bury repaired cables in
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the sea floor using high-powered water jets.
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70% of cable damage is caused by man-made activity, of which over a third
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is a result of fishing activity; another quarter is as a result ship anchors
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\begin_inset CommandInset citation
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LatexCommand citep
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key "ultra-map-cable-damage-causes"
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literal "false"
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\end_inset
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As such, the ability to protect sub-sea cables in shallower waters by burying
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them from human intervention is a key parameter in protecting cables from
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further damage.
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While this can be completed with a separate plough, this would require
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more deck space, motion of the surface vessel.
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Ploughs are also typically extremely heavy pieces of equipment and would
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make the vessel less efficient overall.
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\end_layout
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\begin_layout Standard
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The need for fine movement control and actuators with which to manipulate
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cables has led to box frame vehicles dominating this field, figure
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\begin_inset CommandInset ref
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LatexCommand ref
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reference "fig:The-HECTOR-7-ROV"
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plural "false"
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caps "false"
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noprefix "false"
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\end_inset
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shows SIMEC Technology's HECTOR-7 ROV, a typical design for sub-sea cable
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repair vehicles.
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\end_layout
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\begin_layout Standard
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\begin_inset Float figure
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wide false
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sideways false
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status open
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\begin_layout Plain Layout
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\noindent
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\align center
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\begin_inset Graphics
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filename hector-7.jpg
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lyxscale 50
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width 50col%
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\end_inset
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\end_layout
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\begin_layout Plain Layout
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\begin_inset Caption Standard
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\begin_layout Plain Layout
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SIMEC Technology's HECTOR-7 ROV used on Orange Marine's Pierre de Fermat,
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\begin_inset CommandInset citation
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LatexCommand citep
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key "rov-hector-7-datasheet"
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literal "false"
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\end_inset
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\begin_inset CommandInset label
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LatexCommand label
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name "fig:The-HECTOR-7-ROV"
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\end_inset
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\end_layout
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\end_inset
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\end_layout
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\end_inset
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\end_layout
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\begin_layout Standard
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\begin_inset Flex TODO Note (Margin)
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status open
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\begin_layout Plain Layout
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Limited depth
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\end_layout
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\end_inset
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\end_layout
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\begin_layout Standard
|
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Table
|
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\begin_inset CommandInset ref
|
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|
LatexCommand ref
|
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|
|
reference "tab:ROV-specs"
|
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|
plural "false"
|
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|
caps "false"
|
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noprefix "false"
|
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\end_inset
|
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|
lists the specifications for the ROVs currently being used as part of the
|
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|
|
ACMA cable repair agreement along with similarly classed vehicles from
|
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|
|
other providers.
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|
\end_layout
|
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\begin_layout Standard
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\begin_inset Float table
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wide false
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sideways false
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status open
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\begin_layout Plain Layout
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\noindent
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|
\align center
|
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|
\begin_inset Tabular
|
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|
<lyxtabular version="3" rows="8" columns="5">
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|
<features tabularvalignment="middle">
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|
<column alignment="center" valignment="top">
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|
<column alignment="center" valignment="top">
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|
<column alignment="center" valignment="top" width="0pt">
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|
<column alignment="center" valignment="top">
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|
<column alignment="center" valignment="top">
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|
<row>
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|
<cell alignment="center" valignment="top" bottomline="true" usebox="none">
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|
\begin_inset Text
|
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\begin_layout Plain Layout
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\end_layout
|
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\end_inset
|
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|
</cell>
|
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|
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
|
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|
\begin_inset Text
|
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|
\begin_layout Plain Layout
|
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|
|
\series bold
|
|
|
|
|
HECTOR-7
|
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|
|
\end_layout
|
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|
\end_inset
|
|
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|
</cell>
|
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|
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
|
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|
|
\begin_inset Text
|
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|
\begin_layout Plain Layout
|
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|
\series bold
|
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|
|
|
Atlas
|
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|
|
\end_layout
|
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|
\end_inset
|
|
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|
|
</cell>
|
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|
|
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
|
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|
\begin_inset Text
|
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|
\begin_layout Plain Layout
|
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|
|
\series bold
|
|
|
|
|
ST200
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\end_inset
|
|
|
|
|
</cell>
|
|
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|
|
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
|
|
|
|
|
\begin_inset Text
|
|
|
|
|
|
|
|
|
|
\begin_layout Plain Layout
|
|
|
|
|
|
|
|
|
|
\series bold
|
|
|
|
|
QTrencher 600
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\end_inset
|
|
|
|
|
</cell>
|
|
|
|
|
</row>
|
|
|
|
|
<row>
|
|
|
|
|
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
|
|
|
|
|
\begin_inset Text
|
|
|
|
|
|
|
|
|
|
\begin_layout Plain Layout
|
|
|
|
|
|
|
|
|
|
\series bold
|
|
|
|
|
Company
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\end_inset
|
|
|
|
|
</cell>
|
|
|
|
|
<cell alignment="center" valignment="top" leftline="true" usebox="none">
|
|
|
|
|
\begin_inset Text
|
|
|
|
|
|
|
|
|
|
\begin_layout Plain Layout
|
|
|
|
|
SIMEC Technology
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\end_inset
|
|
|
|
|
</cell>
|
|
|
|
|
<cell multicolumn="1" alignment="center" valignment="top" leftline="true" usebox="none">
|
|
|
|
|
\begin_inset Text
|
|
|
|
|
|
|
|
|
|
\begin_layout Plain Layout
|
|
|
|
|
Global Marine
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\end_inset
|
|
|
|
|
</cell>
|
|
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|
|
<cell multicolumn="2" alignment="center" valignment="top" leftline="true" usebox="none">
|
|
|
|
|
\begin_inset Text
|
|
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|
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|
|
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|
\begin_layout Plain Layout
|
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|
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|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\end_inset
|
|
|
|
|
</cell>
|
|
|
|
|
<cell alignment="center" valignment="top" leftline="true" rightline="true" usebox="none">
|
|
|
|
|
\begin_inset Text
|
|
|
|
|
|
|
|
|
|
\begin_layout Plain Layout
|
|
|
|
|
SMD
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\end_inset
|
|
|
|
|
</cell>
|
|
|
|
|
</row>
|
|
|
|
|
<row>
|
|
|
|
|
<cell multirow="3" alignment="center" valignment="middle" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
|
|
|
|
|
\begin_inset Text
|
|
|
|
|
|
|
|
|
|
\begin_layout Plain Layout
|
|
|
|
|
|
|
|
|
|
\series bold
|
|
|
|
|
Vessel
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\end_inset
|
|
|
|
|
</cell>
|
|
|
|
|
<cell multirow="3" alignment="center" valignment="middle" topline="true" bottomline="true" leftline="true" usebox="none">
|
|
|
|
|
\begin_inset Text
|
|
|
|
|
|
|
|
|
|
\begin_layout Plain Layout
|
|
|
|
|
Pierre de Fermat
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\end_inset
|
|
|
|
|
</cell>
|
|
|
|
|
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
|
|
|
|
|
\begin_inset Text
|
|
|
|
|
|
|
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|
|
\begin_layout Plain Layout
|
|
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|
|
Wave Sentinel
|
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|
|
\end_layout
|
|
|
|
|
|
|
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|
|
\end_inset
|
|
|
|
|
</cell>
|
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|
|
<cell multirow="3" alignment="center" valignment="middle" topline="true" bottomline="true" leftline="true" usebox="none">
|
|
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|
|
\begin_inset Text
|
|
|
|
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|
|
\begin_layout Plain Layout
|
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|
|
Cable Innovator
|
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|
|
\end_layout
|
|
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|
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|
|
|
|
|
\end_inset
|
|
|
|
|
</cell>
|
|
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|
|
<cell multirow="3" alignment="center" valignment="middle" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
|
|
|
|
|
\begin_inset Text
|
|
|
|
|
|
|
|
|
|
\begin_layout Plain Layout
|
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|
|
N/A
|
|
|
|
|
\end_layout
|
|
|
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|
|
|
|
|
|
\end_inset
|
|
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|
|
</cell>
|
|
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|
|
</row>
|
|
|
|
|
<row>
|
|
|
|
|
<cell multirow="4" alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
|
|
|
|
|
\begin_inset Text
|
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|
|
|
|
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|
|
\begin_layout Plain Layout
|
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|
|
|
|
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|
\end_layout
|
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|
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|
|
|
|
|
|
\end_inset
|
|
|
|
|
</cell>
|
|
|
|
|
<cell multirow="4" alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
|
|
|
|
|
\begin_inset Text
|
|
|
|
|
|
|
|
|
|
\begin_layout Plain Layout
|
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|
|
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|
\end_layout
|
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|
|
|
|
|
|
|
|
\end_inset
|
|
|
|
|
</cell>
|
|
|
|
|
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
|
|
|
|
|
\begin_inset Text
|
|
|
|
|
|
|
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|
|
\begin_layout Plain Layout
|
|
|
|
|
C.S Sovereign
|
|
|
|
|
\end_layout
|
|
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|
|
|
|
|
|
|
\end_inset
|
|
|
|
|
</cell>
|
|
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|
|
<cell multirow="4" alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
|
|
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|
\begin_inset Text
|
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|
|
|
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|
\begin_layout Plain Layout
|
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\end_layout
|
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|
\end_inset
|
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|
|
</cell>
|
|
|
|
|
<cell multirow="4" alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
|
|
|
|
|
\begin_inset Text
|
|
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|
|
|
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|
\begin_layout Plain Layout
|
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|
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|
|
|
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|
\end_layout
|
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|
|
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|
|
|
|
|
\end_inset
|
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|
|
|
</cell>
|
|
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|
|
</row>
|
|
|
|
|
<row>
|
|
|
|
|
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
|
|
|
|
|
\begin_inset Text
|
|
|
|
|
|
|
|
|
|
\begin_layout Plain Layout
|
|
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|
|
|
|
|
|
|
\series bold
|
|
|
|
|
Depth Rating
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\end_inset
|
|
|
|
|
</cell>
|
|
|
|
|
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
|
|
|
|
|
\begin_inset Text
|
|
|
|
|
|
|
|
|
|
\begin_layout Plain Layout
|
|
|
|
|
3,000 m
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\end_inset
|
|
|
|
|
</cell>
|
|
|
|
|
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
|
|
|
|
|
\begin_inset Text
|
|
|
|
|
|
|
|
|
|
\begin_layout Plain Layout
|
|
|
|
|
2,000 m
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\end_inset
|
|
|
|
|
</cell>
|
|
|
|
|
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
|
|
|
|
|
\begin_inset Text
|
|
|
|
|
|
|
|
|
|
\begin_layout Plain Layout
|
|
|
|
|
2,500 m
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\end_inset
|
|
|
|
|
</cell>
|
|
|
|
|
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
|
|
|
|
|
\begin_inset Text
|
|
|
|
|
|
|
|
|
|
\begin_layout Plain Layout
|
|
|
|
|
3,000 m
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\end_inset
|
|
|
|
|
</cell>
|
|
|
|
|
</row>
|
|
|
|
|
<row>
|
|
|
|
|
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
|
|
|
|
|
\begin_inset Text
|
|
|
|
|
|
|
|
|
|
\begin_layout Plain Layout
|
|
|
|
|
|
|
|
|
|
\series bold
|
|
|
|
|
Weight in Air
|
|
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|
|
\end_layout
|
|
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|
|
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\end_inset
|
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</cell>
|
|
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|
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
|
|
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|
|
\begin_inset Text
|
|
|
|
|
|
|
|
|
|
\begin_layout Plain Layout
|
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|
|
9 t
|
|
|
|
|
\end_layout
|
|
|
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|
|
|
|
|
|
\end_inset
|
|
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|
</cell>
|
|
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|
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
|
|
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|
|
\begin_inset Text
|
|
|
|
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|
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|
|
\begin_layout Plain Layout
|
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|
|
|
10.6 t
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\end_inset
|
|
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|
</cell>
|
|
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|
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
|
|
|
|
|
\begin_inset Text
|
|
|
|
|
|
|
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|
|
\begin_layout Plain Layout
|
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|
|
|
6.5 t
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\end_inset
|
|
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|
</cell>
|
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|
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
|
|
|
|
|
\begin_inset Text
|
|
|
|
|
|
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|
|
\begin_layout Plain Layout
|
|
|
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|
11 t
|
|
|
|
|
\end_layout
|
|
|
|
|
|
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|
|
|
\end_inset
|
|
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</cell>
|
|
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</row>
|
|
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|
|
<row>
|
|
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|
|
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
|
|
|
|
|
\begin_inset Text
|
|
|
|
|
|
|
|
|
|
\begin_layout Plain Layout
|
|
|
|
|
|
|
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|
|
\series bold
|
|
|
|
|
Power
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\end_inset
|
|
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|
|
</cell>
|
|
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|
|
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
|
|
|
|
|
\begin_inset Text
|
|
|
|
|
|
|
|
|
|
\begin_layout Plain Layout
|
|
|
|
|
300 kW
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\end_inset
|
|
|
|
|
</cell>
|
|
|
|
|
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
|
|
|
|
|
\begin_inset Text
|
|
|
|
|
|
|
|
|
|
\begin_layout Plain Layout
|
|
|
|
|
300 kW
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\end_inset
|
|
|
|
|
</cell>
|
|
|
|
|
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
|
|
|
|
|
\begin_inset Text
|
|
|
|
|
|
|
|
|
|
\begin_layout Plain Layout
|
|
|
|
|
-
|
|
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|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\end_inset
|
|
|
|
|
</cell>
|
|
|
|
|
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
|
|
|
|
|
\begin_inset Text
|
|
|
|
|
|
|
|
|
|
\begin_layout Plain Layout
|
|
|
|
|
450 kW
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\end_inset
|
|
|
|
|
</cell>
|
|
|
|
|
</row>
|
|
|
|
|
<row>
|
|
|
|
|
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
|
|
|
|
|
\begin_inset Text
|
|
|
|
|
|
|
|
|
|
\begin_layout Plain Layout
|
|
|
|
|
|
|
|
|
|
\series bold
|
|
|
|
|
Burial Depth
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\end_inset
|
|
|
|
|
</cell>
|
|
|
|
|
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
|
|
|
|
|
\begin_inset Text
|
|
|
|
|
|
|
|
|
|
\begin_layout Plain Layout
|
|
|
|
|
2 m
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\end_inset
|
|
|
|
|
</cell>
|
|
|
|
|
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
|
|
|
|
|
\begin_inset Text
|
|
|
|
|
|
|
|
|
|
\begin_layout Plain Layout
|
|
|
|
|
2 m
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\end_inset
|
|
|
|
|
</cell>
|
|
|
|
|
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
|
|
|
|
|
\begin_inset Text
|
|
|
|
|
|
|
|
|
|
\begin_layout Plain Layout
|
|
|
|
|
1.5 m
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\end_inset
|
|
|
|
|
</cell>
|
|
|
|
|
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
|
|
|
|
|
\begin_inset Text
|
|
|
|
|
|
|
|
|
|
\begin_layout Plain Layout
|
|
|
|
|
3 m
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\end_inset
|
|
|
|
|
</cell>
|
|
|
|
|
</row>
|
|
|
|
|
</lyxtabular>
|
|
|
|
|
|
|
|
|
|
\end_inset
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
\begin_inset VSpace smallskip
|
|
|
|
|
\end_inset
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\begin_layout Plain Layout
|
|
|
|
|
\begin_inset CommandInset citation
|
|
|
|
|
LatexCommand citep
|
|
|
|
|
key "rov-hector-7-datasheet,global-marine-atlas-data-sheet,glboal-marine-st200-datasheet,smd-qtrencher-600-datasheet"
|
|
|
|
|
literal "false"
|
|
|
|
|
|
|
|
|
|
\end_inset
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\begin_layout Plain Layout
|
|
|
|
|
\begin_inset Caption Standard
|
|
|
|
|
|
|
|
|
|
\begin_layout Plain Layout
|
|
|
|
|
Relevant specifications and operating capabilities for sub-sea cable repair
|
|
|
|
|
ROVs
|
|
|
|
|
\begin_inset CommandInset label
|
|
|
|
|
LatexCommand label
|
|
|
|
|
name "tab:ROV-specs"
|
|
|
|
|
|
|
|
|
|
\end_inset
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\end_inset
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\end_inset
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
\end_layout
|
|
|
|
|
|
2020-12-14 20:24:08 +00:00
|
|
|
\begin_layout Paragraph
|
|
|
|
|
Requirements Specification
|
|
|
|
|
\end_layout
|
|
|
|
|
|
2020-12-16 16:41:24 +00:00
|
|
|
\begin_layout Standard
|
|
|
|
|
Using this information the requirements for a cable repair UUV could be
|
|
|
|
|
described as the following,
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\begin_layout Enumerate
|
|
|
|
|
The UUV should have actuators in order to both cut and grip cables
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\begin_layout Enumerate
|
|
|
|
|
The UUV should be able to operate to at least 2 km of depth
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\begin_layout Enumerate
|
|
|
|
|
The UUV should be able to locate the cable without visual information i.e.
|
|
|
|
|
electromagnetically
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\begin_deeper
|
|
|
|
|
\begin_layout Enumerate
|
|
|
|
|
In shallower water the cable is buried and will not be able to be visually
|
|
|
|
|
identified
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\end_deeper
|
|
|
|
|
\begin_layout Enumerate
|
|
|
|
|
The UUV should be able to re-bury the cable in shallower waters
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\begin_deeper
|
|
|
|
|
\begin_layout Enumerate
|
|
|
|
|
This should provide more protection to the cable from interference including
|
|
|
|
|
fishing operations
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\end_deeper
|
2020-12-14 20:24:08 +00:00
|
|
|
\begin_layout Subsubsection
|
|
|
|
|
Current AUV Usage
|
|
|
|
|
\end_layout
|
|
|
|
|
|
2020-12-16 16:41:24 +00:00
|
|
|
\begin_layout Standard
|
|
|
|
|
Autonomous underwater vehicles are well suited to survey and research operations
|
2020-12-18 17:56:59 +00:00
|
|
|
; without human intervention they sweep a given area collecting data for
|
2020-12-16 16:41:24 +00:00
|
|
|
analysis.
|
|
|
|
|
This can include bathymetry
|
|
|
|
|
\begin_inset Foot
|
|
|
|
|
status open
|
|
|
|
|
|
|
|
|
|
\begin_layout Plain Layout
|
2020-12-18 17:56:59 +00:00
|
|
|
Measurement of the depth of a body of water
|
2020-12-16 16:41:24 +00:00
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\end_inset
|
|
|
|
|
|
|
|
|
|
, surveys and chemical composition investigations such as pH and toxin levels.
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\begin_layout Standard
|
|
|
|
|
\begin_inset Float figure
|
|
|
|
|
wide false
|
|
|
|
|
sideways false
|
|
|
|
|
status open
|
|
|
|
|
|
|
|
|
|
\begin_layout Plain Layout
|
|
|
|
|
\noindent
|
|
|
|
|
\align center
|
|
|
|
|
\begin_inset Graphics
|
|
|
|
|
filename hugin-superior.jpg
|
|
|
|
|
lyxscale 30
|
|
|
|
|
width 60col%
|
|
|
|
|
|
|
|
|
|
\end_inset
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\begin_layout Plain Layout
|
|
|
|
|
\begin_inset Caption Standard
|
|
|
|
|
|
|
|
|
|
\begin_layout Plain Layout
|
|
|
|
|
Kongsberg Maritime's HUGIN Superior AUV,
|
|
|
|
|
\begin_inset CommandInset citation
|
|
|
|
|
LatexCommand citep
|
|
|
|
|
key "auv-hugin-superior-datasheet"
|
|
|
|
|
literal "false"
|
|
|
|
|
|
|
|
|
|
\end_inset
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\end_inset
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\begin_layout Plain Layout
|
|
|
|
|
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\end_inset
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
\end_layout
|
|
|
|
|
|
2020-12-18 17:56:59 +00:00
|
|
|
\begin_layout Subsubsection
|
|
|
|
|
Advantages
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\begin_layout Standard
|
|
|
|
|
An advantage of using an autonomous vehicle would be the lack of need for
|
|
|
|
|
the surface vessel to maintain position directly above the ROV and fault;
|
|
|
|
|
instead the surface vessel would stay within a larger area only to maintain
|
|
|
|
|
contact with the UUV.
|
|
|
|
|
This could reduce the required power directed to dynamic positioning which
|
|
|
|
|
in higher sea states can become a significant draw.
|
|
|
|
|
Additionally as the UUV can move independently, the surface vehicle would
|
|
|
|
|
not need to directly track the vehicles movement; for example when the
|
|
|
|
|
UUV is re-burying the repaired cable in shallower waters.
|
|
|
|
|
This would, again, lower the required propulsion power used by the surface
|
|
|
|
|
vessel.
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\begin_layout Standard
|
|
|
|
|
Another advantage could be a reduction in risk during mission operations.
|
|
|
|
|
With a traditional tethered ROV, should the umbilical cable be broken the
|
|
|
|
|
vehicle would likely lose functionality and require specialist recovery.
|
|
|
|
|
This break could occur as a result of a fault in the tether management
|
|
|
|
|
system, high storm activity causing too much tension on the system, or
|
|
|
|
|
in less likely scenarios, animal intervention.
|
|
|
|
|
An autonomous vehicle has no tether to break and a hybrid ROV/AUV could
|
|
|
|
|
likely be instructed to take control and return home should the tether
|
|
|
|
|
break during missions involving direct human control.
|
|
|
|
|
\end_layout
|
|
|
|
|
|
2020-12-14 20:24:08 +00:00
|
|
|
\begin_layout Subsubsection
|
|
|
|
|
Domain Challenges
|
|
|
|
|
\end_layout
|
|
|
|
|
|
2020-12-16 16:41:24 +00:00
|
|
|
\begin_layout Paragraph
|
|
|
|
|
Navigation
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\begin_layout Standard
|
2020-12-18 17:56:59 +00:00
|
|
|
As mentioned, one of the main advantages of using an autonomous vehicle
|
|
|
|
|
for sub-sea cable repairs would be the physical de-coupling of the vehicles,
|
|
|
|
|
however this also poses the most significant challenge.
|
2020-12-16 16:41:24 +00:00
|
|
|
In typical ROV operations, the operator has knowledge of the location of
|
|
|
|
|
the ROV relative to the surface vessel.
|
2020-12-18 17:56:59 +00:00
|
|
|
As the surface vessel is GNSS
|
|
|
|
|
\begin_inset Foot
|
|
|
|
|
status open
|
|
|
|
|
|
|
|
|
|
\begin_layout Plain Layout
|
|
|
|
|
Global Navigation Satellite System, the generic term for satellite aided
|
|
|
|
|
global navigation of which the American GPS, Russian GLONASS and European
|
|
|
|
|
Galileo systems are examples
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\end_inset
|
|
|
|
|
|
|
|
|
|
-enabled (Likely GPS) it has knowledge of its position in world co-ordinates
|
|
|
|
|
and the operator can use this to reduce the ROV's cable search space.
|
2020-12-16 16:41:24 +00:00
|
|
|
\begin_inset Flex TODO Note (Margin)
|
|
|
|
|
status open
|
|
|
|
|
|
|
|
|
|
\begin_layout Plain Layout
|
|
|
|
|
Diagram?
|
|
|
|
|
\end_layout
|
|
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|
|
\end_inset
|
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|
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|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\begin_layout Standard
|
|
|
|
|
Decoupling the vehicles introduces complications that are not necessarily
|
|
|
|
|
typical to the existing use cases for AUVs.
|
|
|
|
|
The frequency of EM waves used by GNSS systems do not penetrate deep through
|
|
|
|
|
the water and an AUV must be able to operate without world co-ordinates
|
|
|
|
|
provided in this manner.
|
|
|
|
|
As such, navigation systems used by AUVs are typically
|
|
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|
|
\emph on
|
|
|
|
|
dead reckoning
|
|
|
|
|
\emph default
|
|
|
|
|
systems.
|
|
|
|
|
This is a form of navigation that operates relative to a known fixed point
|
|
|
|
|
(where a UUV is deployed for example) as opposed to one relative to world
|
|
|
|
|
co-ordinates.
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\begin_layout Standard
|
|
|
|
|
With an accurate system, this will satisfy many surveying and research use
|
|
|
|
|
cases where relative location data can be transformed to world-coordinates
|
|
|
|
|
after the fact.
|
|
|
|
|
This will prove less effective when the vehicle is expected to autonomously
|
|
|
|
|
navigate to a specific location (the cable fault).
|
|
|
|
|
A dead reckoning system as described above uses relative sensors to measure
|
|
|
|
|
it's speed and infer it's current location however these relative sensors
|
|
|
|
|
have associated measurement errors which accumulate over time.
|
|
|
|
|
This would be more pronounced under the water where sea currents are liable
|
|
|
|
|
to accentuate these errors, the efficacy of an AUV's fault location capabilitie
|
|
|
|
|
s may be reduced to the point of unacceptability.
|
|
|
|
|
\begin_inset Flex TODO Note (Margin)
|
|
|
|
|
status open
|
|
|
|
|
|
|
|
|
|
\begin_layout Plain Layout
|
|
|
|
|
Kalman filter now?
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\end_inset
|
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|
|
|
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|
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|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\begin_layout Paragraph
|
|
|
|
|
Launch & Recovery
|
|
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|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\begin_layout Standard
|
|
|
|
|
\begin_inset Flex TODO Note (Margin)
|
|
|
|
|
status open
|
|
|
|
|
|
|
|
|
|
\begin_layout Plain Layout
|
|
|
|
|
Top hat or garage TMS to act as LARS interface?
|
|
|
|
|
\end_layout
|
|
|
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|
|
|
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|
|
\end_inset
|
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|
|
|
|
|
|
|
|
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\begin_layout Subsubsection
|
|
|
|
|
Proposed Design
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\begin_layout Standard
|
|
|
|
|
The vehicle will be designed for hybrid ROV/AUV operations.
|
|
|
|
|
The vehicle should be able to complete missions independently of the surface
|
|
|
|
|
vessel with the ability to operate in a similar fashion to existing ROVs
|
|
|
|
|
(human controller, tethered power and data connection).
|
|
|
|
|
This will have a number of benefits, primarily that the vehicle should
|
2020-12-18 17:56:59 +00:00
|
|
|
be able to benefit from autonomous operation where possible with the ability
|
|
|
|
|
for direct human control in missions deemed to complex for autonomous control.
|
2020-12-16 16:41:24 +00:00
|
|
|
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\begin_layout Standard
|
|
|
|
|
The existing remit of AUV operations is primarily survey, inspection and
|
|
|
|
|
light intervention, it is likely that the autonomous capabilities of this
|
|
|
|
|
vehicle would not be capable of conducting all existing cable repair missions
|
|
|
|
|
which involve a lot more involved intervention.
|
|
|
|
|
It is important that enabling autonomous operations does not ultimately
|
|
|
|
|
reduce it's operating capabilities.
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\begin_layout Standard
|
|
|
|
|
As previously described, box frame UUVs are well suited to sub-sea cable
|
|
|
|
|
operations where fine movement control and space for actuators are critical.
|
|
|
|
|
As such a box frame of similar specifications to those currently used,
|
|
|
|
|
|
|
|
|
|
\begin_inset CommandInset citation
|
2020-12-18 17:56:59 +00:00
|
|
|
LatexCommand citep
|
2020-12-16 16:41:24 +00:00
|
|
|
key "global-marine-atlas-data-sheet,rov-hector-7-datasheet"
|
|
|
|
|
literal "false"
|
|
|
|
|
|
|
|
|
|
\end_inset
|
|
|
|
|
|
|
|
|
|
will be used.
|
|
|
|
|
The vehicle will likely be at the larger and heavier end of existing ROVs
|
|
|
|
|
as the vehicle must now have the onboard energy capabilities to complete
|
|
|
|
|
a mission without a constant power supply from the surface vessel.
|
|
|
|
|
\end_layout
|
|
|
|
|
|
2020-12-18 17:56:59 +00:00
|
|
|
\begin_layout Subsubsection
|
|
|
|
|
Communication
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\begin_layout Standard
|
|
|
|
|
As the UUV is now expected to operate independently of the surface vessel,
|
|
|
|
|
it should have the ability to bi-directionally wirelessly communicate with
|
|
|
|
|
the surface vessel.
|
|
|
|
|
Uses for such a communications channel include the UUV reporting it's mission
|
|
|
|
|
status and the surface vessel providing high-level instructions such as
|
|
|
|
|
|
|
|
|
|
\emph on
|
|
|
|
|
return home
|
|
|
|
|
\emph default
|
|
|
|
|
orders.
|
|
|
|
|
When operating underwater, acoustic signals are the primary medium for
|
|
|
|
|
wireless communication.
|
|
|
|
|
|
|
|
|
|
\end_layout
|
|
|
|
|
|
2020-12-14 20:24:08 +00:00
|
|
|
\begin_layout Subsubsection
|
|
|
|
|
Navigation
|
|
|
|
|
\end_layout
|
|
|
|
|
|
2020-12-16 16:41:24 +00:00
|
|
|
\begin_layout Standard
|
|
|
|
|
As previously described, the navigation system will primarily be built on
|
|
|
|
|
the principle of
|
|
|
|
|
\emph on
|
|
|
|
|
dead reckoning
|
|
|
|
|
\emph default
|
|
|
|
|
using an inertial navigation system (INS).
|
|
|
|
|
An INS uses input from many types of sensor such as accelerometers and
|
|
|
|
|
gyroscopes to measure the movement of the vehicle and hence infer it's
|
|
|
|
|
location.
|
|
|
|
|
None of these could individually provide an accurate determination of location
|
|
|
|
|
and as such
|
|
|
|
|
\emph on
|
|
|
|
|
sensor fusion
|
|
|
|
|
\emph default
|
|
|
|
|
is employed.
|
|
|
|
|
Each sensor has an associated measurement uncertainty which compounds over
|
|
|
|
|
time, sensor fusion allows all the sensor measurements to be combined in
|
|
|
|
|
such a way as to produce a single output measurement with an uncertainty
|
|
|
|
|
smaller than any of each sensor individually.
|
|
|
|
|
A common method for implementing sensor fusion is using a
|
|
|
|
|
\emph on
|
|
|
|
|
Kalman filter
|
|
|
|
|
\emph default
|
|
|
|
|
|
|
|
|
|
\begin_inset Flex TODO Note (Margin)
|
|
|
|
|
status open
|
|
|
|
|
|
|
|
|
|
\begin_layout Plain Layout
|
|
|
|
|
reference, explain?
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\end_inset
|
|
|
|
|
|
|
|
|
|
.
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\begin_layout Standard
|
|
|
|
|
However, despite the use of a Kalman filter allowing more precise approximations
|
|
|
|
|
of the vehicles relative location, the lack of external calibrating updates
|
|
|
|
|
means that the overall uncertainty will still continually increase over
|
|
|
|
|
time.
|
|
|
|
|
In land-based robotics this is mitigated through the use of periodic GPS
|
2020-12-18 17:56:59 +00:00
|
|
|
measurements which have low, constant uncertainty and help to place an
|
|
|
|
|
upper bound on the overall error.
|
2020-12-16 16:41:24 +00:00
|
|
|
As previously mentioned, GNSS systems do not work deep underwater and as
|
|
|
|
|
such, another method for providing these external updates must be used.
|
2020-12-18 17:56:59 +00:00
|
|
|
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\begin_layout Standard
|
|
|
|
|
The following proposes methods for providing global positioning to the UUV
|
|
|
|
|
without a traditional GNSS system.
|
|
|
|
|
This will be completed in two stages, the first being to provide the UUV
|
|
|
|
|
with the ability to measure the location of a fixed point relative to itself.
|
|
|
|
|
In parallel, the global co-ordinates of this fixed point will be communicated
|
|
|
|
|
to the UUV in order to infer it's own global location.
|
2020-12-16 16:41:24 +00:00
|
|
|
\end_layout
|
|
|
|
|
|
2020-12-14 20:24:08 +00:00
|
|
|
\begin_layout Paragraph
|
|
|
|
|
Underwater Acoustic Positioning
|
|
|
|
|
\end_layout
|
|
|
|
|
|
2020-12-18 17:56:59 +00:00
|
|
|
\begin_layout Standard
|
|
|
|
|
Alongisde the use of acoustic signals for communications it will also be
|
|
|
|
|
employed for positioning.
|
|
|
|
|
One application for this is underwater acoustic positioning which employs
|
|
|
|
|
the use of time-of-flight measurements to beacons of a known location to
|
|
|
|
|
triangulate an object's location.
|
|
|
|
|
There are different configurations for such a system depending on how these
|
|
|
|
|
beacons are laid out,
|
|
|
|
|
\emph on
|
|
|
|
|
long-baseline
|
|
|
|
|
\emph default
|
|
|
|
|
(LBL) systems involve beacons located on the sea floor.
|
|
|
|
|
Spreading these beacons around the working area of an ROV widens the baseline
|
|
|
|
|
of the system and provides higher accuracy when triangulating.
|
|
|
|
|
This configuration is best suited to static areas of research such as ship
|
|
|
|
|
wrecks where an initial time devoted to deploying and calibrating these
|
|
|
|
|
underwater beacons is a reasonable expense to pay for the required high
|
|
|
|
|
accuracy.
|
|
|
|
|
This is not the case for sub-sea cable repairs where the deployment, calibratio
|
|
|
|
|
n and recovery of beacons on the seabed would be prohibitively complex and
|
|
|
|
|
add significant time to the duration of a mission.
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\begin_layout Standard
|
|
|
|
|
|
|
|
|
|
\emph on
|
|
|
|
|
Short-baseline
|
|
|
|
|
\emph default
|
|
|
|
|
(SBL) systems involve a number of beacons placed at the furthest corners
|
|
|
|
|
of the surface vessel, this has the benefit of requiring little set-up
|
|
|
|
|
and pack-down at the cost of reduced accuracy.
|
|
|
|
|
Relative to the UUV these beacons are all on a similar bearing when operating
|
|
|
|
|
at a distance, as a result changes in the vehicle's location would be reflected
|
|
|
|
|
in similar changes to the measurements from all of the beacons.
|
|
|
|
|
Previously, with a long-baseline, the beacons are ideally surrounding the
|
|
|
|
|
UUV's working area and changes in its location are reflected in different
|
|
|
|
|
distance deltas for each beacon allowing tighter triangulation.
|
|
|
|
|
Accuracy can be improved by extending the beacons away from the vessel
|
|
|
|
|
to extend the baseline as far as possible.
|
|
|
|
|
\begin_inset Flex TODO Note (Margin)
|
|
|
|
|
status open
|
|
|
|
|
|
|
|
|
|
\begin_layout Plain Layout
|
|
|
|
|
such as on a boom?
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\end_inset
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\begin_layout Standard
|
|
|
|
|
One method to mitigate the drawbacks of both described methods is by using
|
|
|
|
|
GPS Intelligent Buoys (GIBs).
|
|
|
|
|
This configuration, also referred to as an
|
|
|
|
|
\emph on
|
|
|
|
|
inverted long-baseline
|
|
|
|
|
\emph default
|
|
|
|
|
, allows a much wider baseline than the surface-vessel-mounted beacons by
|
|
|
|
|
deploying a group of
|
|
|
|
|
\emph on
|
|
|
|
|
smart buoys
|
|
|
|
|
\emph default
|
|
|
|
|
around the expected working area of the UUV.
|
|
|
|
|
The use of buoys as opposed to beacons on the sea-floor significantly decreases
|
|
|
|
|
the preparation and clean-up mission phases.
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\begin_layout Standard
|
|
|
|
|
Of these methods it is proposed that the surface vessel be equipped with
|
|
|
|
|
a short-baseline beacon array as well as a population of GIBs.
|
|
|
|
|
This will allow the choice between higher accuracy or faster mission turnaround
|
|
|
|
|
be decided by mission conditions as well as providing redundancy for either
|
|
|
|
|
system.
|
|
|
|
|
In shallower waters, the accuracy of the onboard SBL may be deemed sufficient
|
|
|
|
|
however in deeper water where the UUV is operating far further from the
|
|
|
|
|
surface vessel, the compactness of the SBL baseline may require the higher
|
|
|
|
|
accuracy of the GIBs
|
|
|
|
|
\begin_inset Foot
|
|
|
|
|
status open
|
|
|
|
|
|
|
|
|
|
\begin_layout Plain Layout
|
|
|
|
|
In practice the two could be used in conjunction for efficiency.
|
|
|
|
|
As the UUV is deployed it initially uses the onboard SBL array while the
|
|
|
|
|
surface vessel makes a pass around the working area deploying GIBs for
|
|
|
|
|
use as the UUV gets deeper
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\end_inset
|
|
|
|
|
|
|
|
|
|
.
|
|
|
|
|
The GIBs would be considered additional accuracy, the SBL would be used
|
|
|
|
|
alongside the GIBs and act as an extra node in the array.
|
|
|
|
|
Additionally the weather and sea conditions could play a factor in the
|
|
|
|
|
decision.
|
|
|
|
|
In higher sea states and stormy weather, the deployment and recovery of
|
|
|
|
|
GIBs may be deemed too risky and the SBL could be used alone.
|
|
|
|
|
\end_layout
|
|
|
|
|
|
2020-12-16 16:41:24 +00:00
|
|
|
\begin_layout Paragraph
|
2020-12-18 17:56:59 +00:00
|
|
|
Global Calibration
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\begin_layout Standard
|
|
|
|
|
The above underwater acoustic positioning system will allow the UUV to keep
|
|
|
|
|
track of it's position relative to known points at the surface, however
|
|
|
|
|
this alone will not provide the UUV with its global location.
|
|
|
|
|
In order for the UUV to calibrate it's local map to global co-ordinates,
|
|
|
|
|
the global position of these surface points must be provided.
|
|
|
|
|
This will be conducted over the previously described acoustic communication
|
|
|
|
|
channel.
|
|
|
|
|
As it could be expected that this channel has a low bandwidth, these updates
|
|
|
|
|
need not be excessively frequent.
|
2020-12-16 16:41:24 +00:00
|
|
|
\end_layout
|
|
|
|
|
|
2020-12-14 20:24:08 +00:00
|
|
|
\begin_layout Paragraph
|
|
|
|
|
Acoustic Doppler Current Profiling
|
|
|
|
|
\end_layout
|
|
|
|
|
|
2020-12-18 17:56:59 +00:00
|
|
|
\begin_layout Standard
|
|
|
|
|
While accelerometers and gyroscopes would be expected components of any
|
|
|
|
|
mobile dead reckoning navigation system, additional sensors well-suited
|
|
|
|
|
to sub-sea localisation will allow the vessel's movement to be more precise.
|
|
|
|
|
One such sensor is a
|
|
|
|
|
\emph on
|
|
|
|
|
Doppler velocity log
|
|
|
|
|
\emph default
|
|
|
|
|
which estimates the vessel's velocity by tracking the seabed.
|
|
|
|
|
\end_layout
|
|
|
|
|
|
2020-12-14 20:24:08 +00:00
|
|
|
\begin_layout Subsubsection
|
|
|
|
|
Control
|
|
|
|
|
\end_layout
|
|
|
|
|
|
|
|
|
|
\begin_layout Subsubsection
|
|
|
|
|
Summary
|
2020-12-08 09:57:23 +00:00
|
|
|
\end_layout
|
|
|
|
|
|
2020-12-18 17:56:59 +00:00
|
|
|
\begin_layout Section
|
|
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Digitalisation
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\end_layout
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2020-12-08 09:57:23 +00:00
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\begin_layout Standard
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\begin_inset Newpage newpage
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\end_inset
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\end_layout
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\begin_layout Standard
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\begin_inset CommandInset label
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LatexCommand label
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name "sec:bibliography"
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\end_inset
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\begin_inset CommandInset bibtex
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LatexCommand bibtex
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btprint "btPrintCited"
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bibfiles "references"
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options "bibtotoc"
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\end_inset
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\end_layout
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\begin_layout Standard
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\begin_inset Newpage pagebreak
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\end_inset
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\end_layout
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\begin_layout Section
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\start_of_appendix
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appendix placeholder
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\end_layout
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\end_body
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\end_document
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