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ACT Autonomous Surface Vehicle Workshop Report
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standard levels of autonomy and supervision are defined categorically the precise
actions to take to meet this risk tolerance become more clear.
Therefore, in the following sections, after first illustrating several kinds of operational
environments to provide context for future discussion, five levels of autonomy and
three levels of supervision are proposed. In defining these levels, a standard is set that
may be adopted by vessel manufacturers, operators and the public to clarify their
communications and thinking about operation of autonomous marine vessels.
Operational Environment
Operational environments vary greatly in the level of risk presented to unmanned
vehicles. Ports and harbors present a very complex, high risk environment in which an
unmanned system would have to contend with a high density of other vessel traffic,
complex vessel traffic routing schemes, fishing gear, and other navigational hazards.
Polar areas are unlikely to present similar hazards and the unmanned system may not
encounter any other vessels or obstacles at all, but can present other risks, such as ice
and remote operations, that may require very robust systems. At the other end of the
range, unmanned systems may be operated in controlled environments, such as lakes or
reservoirs, where the obstacles are known and can be managed in advance.
Additionally, areas with high currents require different considerations from those
without, particularly when the currents are a large fraction of the vessel’s maximum
speed. Weather and sea state further complicate any environment. Therefore, it is
important to recognize the interaction between environment, level of autonomy, and
level of supervision desired when assessing risk and determining the suitability of an
unmanned system for the desired task. The high level of autonomy necessary for
unsupervised operations in a high risk environment, such as a busy harbor, may not be
achievable. However, a system with basic autonomy may be suitable for such an
environment if a high level of supervision is practical. Conversely, basic autonomy may
be all that is necessary to successfully operate a system with very little supervision in a
controlled environment.
Levels of Vessel Autonomy
Because the levels of vessel autonomy can vary so greatly between vessels,
environment and mission it is useful to define them categorically. Well defined levels of
autonomy help to clarify requirements between manufacturers and their customers.
Moreover, they imply a level of the relative risk of operations and therefore ancillary
systems to put in place to mitigate those risks. Thus five levels of autonomy are defined
and described in detail below with examples for illustration. They are: Remote Piloting
(“manual”), Basic Autonomy (“do as you’re told”), Intermediate Autonomy (“do as your
told and react to what’s known”), Advanced Autonomy (“do as your told, sense and
react to what’s not known”) and Planning (“think”).
In addition, when defining the five levels of autonomy it becomes useful to separate the
levels of autonomy into three categories within each level. The three categories are