Reactivity.

Reactivity is crucial to any autonomous system. Unanticipated events will occur, necessitating responses if the agent is to survive and carry out its mission. This is more important for LRAUVs than for many other kinds of autonomous systems, because they will be out of contact with humans for long periods, and they will often be in locations from which it would be difficult if not impossible to retrieve them should they fail. In this, they share features with space vehicles. Moreover, the number of unanticipated events increases with time.

Unanticipated event handling requires several things, including:

• detection of the event;
• diagnosis (to the level of causation needed to respond to the event);
• assessment of the event's importance in the current context; and
• selection and implementation of an appropriate response.