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ACT Autonomous Surface Vehicle Workshop Report
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associated with any autonomous vessel operation, namely, that of the level of
supervision. Levels of supervision are defined here as “Attended”, “Monitored” and
“Independent” operation, described in detail below. When convolved with a particular
environment and informed by levels of autonomy the level of supervision is chosen to
meet a level of tolerable risk.
Attended
Attended operation involves continuous supervision of an autonomous vehicle by
vigilant watchstanders ready to take action in the event of any untoward event. Remote
piloting (Level 1 autonomy) is attended operation, by definition. However, any other
level of autonomy may be attended or not. Operations without constant telemetry
cannot be attended operation, but rather qualify as Monitored or Independent
operation.
Monitored
Monitored operation involves cursory supervision of a vehicle, affording an operator the
ability to focus on other tasks, but ensuring normal operation at regular periodic
intervals and relying to some extent on warnings and alarms from the vehicle in the
event operator assistance is required. Monitored operation requires a basic vehicle
autonomy level at a minimum (the ability to follow a sequential mission plan), but also
the ability to invoke remote piloting and possibly even physical intervention when
necessary. Therefore, monitored operation requires a suitable telemetry link and the
operation within a sufficiently close proximity to intervene if required.
Independent
Independent operation involves little direct supervision of a vehicle other than periodic
review of operations and status, relying largely on warnings and alarms to notify the
operator of faults and events requiring assistance. Independent operation also requires
a complete mission plan composed of a sequential list of mission objectives and or
vessel behaviors under various circumstances, autonomously executed (Levels 2-3 or
above), for both the vessel and its payload sensors. When under Independent
operation, telemetry links may be inadequate to support remote piloting and distances
may be too far for any timely physical intervention.
Scenarios
It is useful to consider several scenarios to illustrate the way in which operators may
choose to meet tolerable levels of risk when operating marine autonomous vehicles.
These scenarios are provided for illustration purposes only. Individual organizations
must define their own levels of tolerable risk and for a given vessel and environment,
the appropriate level of autonomy and supervision to meet it.
Consider a 20 ft. autonomous vessel conducting hydrographic survey 10 nm from shore
in lightly trafficked waters. Assume the weather is clear with sea-state 3 or less. Assume
the vessel has Level 1 Self-awareness (ability to display some parameters but not log
them or activate alarms), Level 2 Operational autonomy (ability to follow sequential list
of mission objectives) and Level 1 Sensor autonomy (manual operation of sensors).