Part B | 16.1
388 Part B Autonomous Ocean Vehicles, Subsystems and Control
vehicles (gliders) and propeller-driven AUVs. Docking was invoked as a method to extend the endurance
of the propeller driven vehicles and to collect and report observed data. It is worth noting that at the time
of the AOSN paper, propeller driven AUVs had typical endurances of a fraction of a day, buoyancy-driven
systems (gliders) did not exist yet, and satellite communication systems like Iridium were still in the future.
The AOSN concept attracted significant effort, and
a range of docking technologies were developed and
demonstrated [16.5–8].
With growing acceptance of survey-class AUVs in
the commercial sector, interest is growing in the use
of AUVs for activities such as periodic inspection of
subsea equipment installations [16.9] and the use of
AUVs for maintenance and repair activities [16.10–12].
Many scenarios envision an AUV that is resident with
the undersea equipment, thus creating a docking requirement. Another scenario uses an AUV to deliver
a package, such as an ROV (remotely operated vehicle) [16.13, 14] to the equipment requiring servicing. In
this scenario, the delivered ROV, once attached, can be
tele-operated using connectivity through the dock and
undersea infrastructure, allowing ROV operations without a ship.
The demands of launch and recovery often limit
the operational use of AUVs. Consequently docking
has been identified as an enabling capability to support
off-board operation of AUVs from submarines [16.15,
16], autonomous surface vessels [16.17], other AUVs
[16.18], ships [16.9], and under ice [16.19, 20]. Even in
circumstances where humans are available to handle recovery, safety factors will limit deck operations as sea
conditions deteriorate. Expanding the weather window
for AUV operations can have important financial benefits for commercial operations, and can be enabling for
military operations. Consequently, automating launch
and recovery is attractive.
The diverse uses of docking systems lead to equally
diverse design strategies. The steps include: navigating
the AUV to the docking device vicinity, approaching the
dock with the appropriate velocity and orientation, and
achieving physical linkage of the AUV and the dock. In
addition, some docking systems integrate communications and power transfer functions into their design, and
in these cases the process of physical linkage is also associated with establishing communications and power
links. Factors influencing the nature of the docking include: is the vehicle docking with a fixed or moving
object? Will the dock provide power to the AUV, or vice
versa? Will a human operator intervene in the process
at any stage? Are there reasons to minimize the amount
of hardware required for docking on either the AUV or
the dock? Even this brief list of questions demonstrates
how different applications might drive a docking system design in very different directions.
16.1 Technical Elements of Docking
To understand the elements of docking, it is useful to
review an example docking scenario. Consider a dock
attached to a cabled observatory that provides power
and high-bandwidth communication to a docked vehicle. The dock itself is a funnel structure (Fig. 16.1) into
which the torpedo-shaped vehicle (Fig. 16.2) will drive
in the docking process. The docking process starts with
the vehicle at a considerable distance, and following
sequence:
En route: the first phase of docking is for the vehicle to navigate to the vicinity of the dock so that it
can directly sense the dock with onboard sensors.
During the en route phase of operations, the vehicle
typically navigates relative to the Earth.
Approach setup: once the vehicle is in the general vicinity of the dock, it must position itself for
an approach to the dock. For example, the vehicle
might use an ultrashort baseline (USBL) acoustic
system that can measure the direction and range to
an acoustic transponder mounted on the dock to position itself in front of the dock cone, aligned for
an approach.
Approach: once the vehicle is positioned appropriately, it can make its approach to the dock.
Approach techniques range from the simple strategy of simply pointing directly at the dock, to
more sophisticated methodologies which attempt
to compensate for currents to follow a specific
trajectory.
Terminal homing: the last segment of the final approach, as the vehicle closes to within a few vehicle
lengths of the dock, is referred to as the terminal
homing phase. The accuracy of the final approach to
the docking funnel can be improved by using a terminal guidance sensor with very high update rate
and high accuracy, for example, an optical homing
system.
Capture: a successful final approach terminates
with the vehicle impacting inside the docking funnel. The vehicle will continue to thrust forward,
driving the nose of the vehicle to the center of the
388 Part B Autonomous Ocean Vehicles, Subsystems and Control
vehicles (gliders) and propeller-driven AUVs. Docking was invoked as a method to extend the endurance
of the propeller driven vehicles and to collect and report observed data. It is worth noting that at the time
of the AOSN paper, propeller driven AUVs had typical endurances of a fraction of a day, buoyancy-driven
systems (gliders) did not exist yet, and satellite communication systems like Iridium were still in the future.
The AOSN concept attracted significant effort, and
a range of docking technologies were developed and
demonstrated [16.5–8].
With growing acceptance of survey-class AUVs in
the commercial sector, interest is growing in the use
of AUVs for activities such as periodic inspection of
subsea equipment installations [16.9] and the use of
AUVs for maintenance and repair activities [16.10–12].
Many scenarios envision an AUV that is resident with
the undersea equipment, thus creating a docking requirement. Another scenario uses an AUV to deliver
a package, such as an ROV (remotely operated vehicle) [16.13, 14] to the equipment requiring servicing. In
this scenario, the delivered ROV, once attached, can be
tele-operated using connectivity through the dock and
undersea infrastructure, allowing ROV operations without a ship.
The demands of launch and recovery often limit
the operational use of AUVs. Consequently docking
has been identified as an enabling capability to support
off-board operation of AUVs from submarines [16.15,
16], autonomous surface vessels [16.17], other AUVs
[16.18], ships [16.9], and under ice [16.19, 20]. Even in
circumstances where humans are available to handle recovery, safety factors will limit deck operations as sea
conditions deteriorate. Expanding the weather window
for AUV operations can have important financial benefits for commercial operations, and can be enabling for
military operations. Consequently, automating launch
and recovery is attractive.
The diverse uses of docking systems lead to equally
diverse design strategies. The steps include: navigating
the AUV to the docking device vicinity, approaching the
dock with the appropriate velocity and orientation, and
achieving physical linkage of the AUV and the dock. In
addition, some docking systems integrate communications and power transfer functions into their design, and
in these cases the process of physical linkage is also associated with establishing communications and power
links. Factors influencing the nature of the docking include: is the vehicle docking with a fixed or moving
object? Will the dock provide power to the AUV, or vice
versa? Will a human operator intervene in the process
at any stage? Are there reasons to minimize the amount
of hardware required for docking on either the AUV or
the dock? Even this brief list of questions demonstrates
how different applications might drive a docking system design in very different directions.
16.1 Technical Elements of Docking
To understand the elements of docking, it is useful to
review an example docking scenario. Consider a dock
attached to a cabled observatory that provides power
and high-bandwidth communication to a docked vehicle. The dock itself is a funnel structure (Fig. 16.1) into
which the torpedo-shaped vehicle (Fig. 16.2) will drive
in the docking process. The docking process starts with
the vehicle at a considerable distance, and following
sequence:
En route: the first phase of docking is for the vehicle to navigate to the vicinity of the dock so that it
can directly sense the dock with onboard sensors.
During the en route phase of operations, the vehicle
typically navigates relative to the Earth.
Approach setup: once the vehicle is in the general vicinity of the dock, it must position itself for
an approach to the dock. For example, the vehicle
might use an ultrashort baseline (USBL) acoustic
system that can measure the direction and range to
an acoustic transponder mounted on the dock to position itself in front of the dock cone, aligned for
an approach.
Approach: once the vehicle is positioned appropriately, it can make its approach to the dock.
Approach techniques range from the simple strategy of simply pointing directly at the dock, to
more sophisticated methodologies which attempt
to compensate for currents to follow a specific
trajectory.
Terminal homing: the last segment of the final approach, as the vehicle closes to within a few vehicle
lengths of the dock, is referred to as the terminal
homing phase. The accuracy of the final approach to
the docking funnel can be improved by using a terminal guidance sensor with very high update rate
and high accuracy, for example, an optical homing
system.
Capture: a successful final approach terminates
with the vehicle impacting inside the docking funnel. The vehicle will continue to thrust forward,
driving the nose of the vehicle to the center of the