Introduction - Autonomous and Autonomic Systems - page 16

large, then control will need to be exercised with minimum delay and at high
rates, necessitating autonomous formation control.
1.3.4 Adjustable and Mixed Autonomy
Complete autonomy may not be desirable or possible for some missions. In
these missions, adjustable and mixed autonomy may need to be used [ 132 ].
In adjustable autonomy, the level of autonomy of the spacecraft can be varied
depending on the circumstances or the desires of mission control. The auton-
omy can be adjusted to be either complete, partial, or no autonomy. In these
cases, the adjustment may be done automatically by the spacecraft depending
on the situation (i.e., the spacecraft may ask for help from mission control), or
may be requested by mission control either to help the spacecraft accomplish
a goal or to perform an action manually. Challenges in adjustable autonomy
include knowing when it needs to be adjusted, as well as how much and how
to make the transition between levels of autonomy.
In mixed autonomy, autonomous agents and people work together to ac-
complish a goal or perform a task. Often the agents perform the low level
details of the task (analogous to the formatting of a paper in a word pro-
cessor), while the human performs the higher-level functions (e.g., analogous
to writing the words of the paper). Challenges in this area are how to get
humans working with the agents, how to divide the work up between the hu-
mans and agents, and how to impart to the humans a sense of cooperation
and coordination, especially if the levels of autonomy are changing over time.
1.4 Agent Technologies
Agent technologies have found themselves in many domains with very different
purposes and competencies. This section discusses some of the issues involved
in the design and implementation of agents, and then it will focus on three
important classes: software agents, robots, and immobots (immobile robots).
Figure 1.5 lists some of the attributes used to describe agents. From the
top-level viewpoint, the two most important attributes of an agent are its
purpose and the domain in which it operates. All other attributes can be
inferred from these two. It is from these attributes that the agent will be
designed and technologies selected.
Figure 1.5 also shows three important classes of agents. Software agents
are intelligent systems that pursue goals for their human owners. An example
would be an information locator that receives some objectives from its owner,
interacts with electronic information sources, locates the desired information,
organizes and prioritizes it, and finally presents it to the owner. Software
agents exist in a virtual computer world and their sensors and actuators are
distributed among the computer systems with which they interact. They may