Autonomous
387
Part B | 16
16. Autonomous Underwater Vehicle Docking
James G. Bellingham
This chapter describes the practical challenges of
docking autonomous underwater vehicles (AUVs)
in the ocean environment and approaches undertaken to create working docking systems. Early
docking work was motivated by the desire to operate AUVs for multiple sorties without recovery or
human servicing of the AUV. To accomplish this,
the docking system provides a method for the AUV
to find the dock, to physically attach, to recharge
AUV batteries, to establish a communication link,
to wait in a low power state for a new mission,
and to undock. A variety of homing methods,
dock configurations, power transfer approaches,
and communications links have been employed
to achieve these respective needs, and are described herein. While the original applications
driving docking were oceanographic in nature,
present interest is broader, driven by commercial and military applications as well. Docking has
been demonstrated, but has not been deployed as
an operational capability, in part because docking
requires an infrastructure for the dock that provides physical mounting, a source of power, and
communication connectivity. The advent of cabled
and mooring-based observatories, and subsea
infrastructure for oil and gas production, create
a foundation supporting docking system deployment. Consequently, the prospects for operational
docking systems seem promising.
16.1 Technical Elements of Docking.............. 388
16.2 AUV Characteristics............................... 390
16.2.1 Vehicle Configuration
and Controllability .................... 390
16.2.2 Vehicle Size............................... 390
16.3 Sensors For Homing ............................. 391
16.3.1 Acoustic Homing ....................... 392
16.3.2 Optical Homing ......................... 393
16.3.3 Electromagnetic
Homing Systems ........................ 394
16.3.4 Constraining Vertical Position ..... 395
16.4 Capture and Connection Mechanisms.... 395
16.4.1 Directional Docks: Funnels ......... 396
16.4.2 Omnidirectional Docks: Poles ..... 397
16.4.3 Soft Docking Approaches ............ 398
16.4.4 Other Docking Mechanisms ........ 398
16.5 Coupling Power and Communications ... 399
16.5.1 Establishing
a Communications Link.............. 399
16.5.2 Power Transfer .......................... 400
16.6 AUV Control Considerations................... 400
16.6.1 Navigation, Currents,
and Arriving at the Dock ............ 400
16.6.2 Managing State: AUV Control....... 401
16.6.3 Managing State:
Coordinating AUV and Dock ........ 401
16.6.4 Detecting and Recovering
from Failures............................. 403
16.7 Conclusions and Future Prospects ......... 403
References................................................... 404
Autonomous underwater vehicle (docking AUV) is the
process whereby an AUV purposefully transitions from
a state of free flight to being physically connected
to another device or platform, called the dock. One
driver for the development of AUV docking stems from
the desire to decrease reliance of AUV operations on
ships and thus enable persistent AUV operations. In effect, if the AUV batteries can be recharged, mission
data retrieved, and a new mission initiated without recovering the AUV to a ship, then the potential exists
to dramatically reduce operational costs and increase
deployment duration. Examples of docks designed to
support extended deployment include docking systems
integrated on moorings [16.1] or attached to cabled observatories [16.2]. The advent of a growing number
of scientific observatories directly enables such AUV
docking concepts, a circumstance recognized early in
the seafloor observatory planning process [16.3].
One of the earliest observing system concepts to
employ docking as a key element was the autonomous
ocean sampling network (AOSN) paradigm [16.4].
AOSN proposed the use of a heterogeneous mix of
vehicles to synoptically characterize dynamic ocean
processes. The system used a mix of buoyancy-driven
387
Part B | 16
16. Autonomous Underwater Vehicle Docking
James G. Bellingham
This chapter describes the practical challenges of
docking autonomous underwater vehicles (AUVs)
in the ocean environment and approaches undertaken to create working docking systems. Early
docking work was motivated by the desire to operate AUVs for multiple sorties without recovery or
human servicing of the AUV. To accomplish this,
the docking system provides a method for the AUV
to find the dock, to physically attach, to recharge
AUV batteries, to establish a communication link,
to wait in a low power state for a new mission,
and to undock. A variety of homing methods,
dock configurations, power transfer approaches,
and communications links have been employed
to achieve these respective needs, and are described herein. While the original applications
driving docking were oceanographic in nature,
present interest is broader, driven by commercial and military applications as well. Docking has
been demonstrated, but has not been deployed as
an operational capability, in part because docking
requires an infrastructure for the dock that provides physical mounting, a source of power, and
communication connectivity. The advent of cabled
and mooring-based observatories, and subsea
infrastructure for oil and gas production, create
a foundation supporting docking system deployment. Consequently, the prospects for operational
docking systems seem promising.
16.1 Technical Elements of Docking.............. 388
16.2 AUV Characteristics............................... 390
16.2.1 Vehicle Configuration
and Controllability .................... 390
16.2.2 Vehicle Size............................... 390
16.3 Sensors For Homing ............................. 391
16.3.1 Acoustic Homing ....................... 392
16.3.2 Optical Homing ......................... 393
16.3.3 Electromagnetic
Homing Systems ........................ 394
16.3.4 Constraining Vertical Position ..... 395
16.4 Capture and Connection Mechanisms.... 395
16.4.1 Directional Docks: Funnels ......... 396
16.4.2 Omnidirectional Docks: Poles ..... 397
16.4.3 Soft Docking Approaches ............ 398
16.4.4 Other Docking Mechanisms ........ 398
16.5 Coupling Power and Communications ... 399
16.5.1 Establishing
a Communications Link.............. 399
16.5.2 Power Transfer .......................... 400
16.6 AUV Control Considerations................... 400
16.6.1 Navigation, Currents,
and Arriving at the Dock ............ 400
16.6.2 Managing State: AUV Control....... 401
16.6.3 Managing State:
Coordinating AUV and Dock ........ 401
16.6.4 Detecting and Recovering
from Failures............................. 403
16.7 Conclusions and Future Prospects ......... 403
References................................................... 404
Autonomous underwater vehicle (docking AUV) is the
process whereby an AUV purposefully transitions from
a state of free flight to being physically connected
to another device or platform, called the dock. One
driver for the development of AUV docking stems from
the desire to decrease reliance of AUV operations on
ships and thus enable persistent AUV operations. In effect, if the AUV batteries can be recharged, mission
data retrieved, and a new mission initiated without recovering the AUV to a ship, then the potential exists
to dramatically reduce operational costs and increase
deployment duration. Examples of docks designed to
support extended deployment include docking systems
integrated on moorings [16.1] or attached to cabled observatories [16.2]. The advent of a growing number
of scientific observatories directly enables such AUV
docking concepts, a circumstance recognized early in
the seafloor observatory planning process [16.3].
One of the earliest observing system concepts to
employ docking as a key element was the autonomous
ocean sampling network (AOSN) paradigm [16.4].
AOSN proposed the use of a heterogeneous mix of
vehicles to synoptically characterize dynamic ocean
processes. The system used a mix of buoyancy-driven