Next: Multiagent Event Handling Up: Handling Events in Previous: Role of context.

Complications Arising from Time-Consuming Actions.
Above, we have discussed the process of event handling as if actions, including communication actions, take negligible time. This is not the case in real world domains, and especially not in relatively slow domains such as AUV control. For example, suppose the agent must move in order to diagnose an event; this could take seconds to minutes. Similarly, communication is slow underwater; the current generation of available acoustic modems have a bit rate of about 1200 baud, and there is a significant time lag arising from the speed of sound in water.

During the time the agent is carrying out actions in support of event handling, the world does not stand still. Information continues to stream into the agent from outside, the world continues to change, and others continue their tasks. The agent cannot, then, suspend event handling while waiting for actions to complete; new events will demand attention, and should be handled.

Two possibilities suggest themselves. One solution is to make the state of event handling explicit, so that the agent can interrupt the handling of one event, then later resume where it left off after the necessary actions have been taken. A problem with this is that until the actions complete, the agent has actually done nothing about the event, which could be catastrophic: consider an event that suggests an AUV may be drifting below its crush depth. The second solution is to allow event handling to finish without waiting for actions, communication, and/or negotiation to finish-but to make only a provisional diagnosis, assessment, and action recommendation. Later, when additional information arrives as a result of the actions or communication, the agent would reevaluate the event in light of the new information. We will investigate the latter solution as this work progresses.



Next: Multiagent Event Handling Up: Handling Events in Previous: Role of context.


rmt@cdps.umcs.maine.edu
Wed May 4 11:21:48 EDT 1994