Page 327 - Introduction to AI Robotics

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Multi-agents
8
on a single reactive agent, societies of reactive agents often exhibit an emer-
gent societal behavior.
Multi-agent societies can be characterized according to where they fall on
at least four dimensions (since multi-agent theory is relatively new, even for
robotics, new dimensions may surface over time). Heterogeneity refers to
whether the member robots are identical in software and hardware. Cooper-
ation may be either active or non-active, while control may fall in the spec-
trum from fully distributed to fully centralized. A robot society may have
a single, explicitly shared goal or each robot may have its own goal. When
communication between agents is appropriate is a pervasive, open question.
From a practical side, the emphasis in multi-agents has been on how fa-
vorable group dynamics emerge from teams of homogeneous, purely reac-
tive robots while operating under distributed control. Problems in emer-
gent societal behaviors such as interference and the need to adapt to the
open world can often been addressed by specifying social rules and internal
motivation. However, more interest is emerging in robots that have either
heterogeneous software or hardware capabilities, such as marsupial and re-
configurable robots. The diversity of a heterogeneous team can be captured
somewhat by the social entropy metric.

8.8 Exercises

Exercise 8.1
Give three reasons why multi-agents are desirable. Describe the general attributes of
applications which are well-suited for multi-agents, and give one example.
Exercise 8.2
Define the following:
a. heterogeneity
b. control
c. cooperation
d. goals
Exercise 8.3
Consider the example of space ants. What would happen if the first robot commu-
nicated with the other robots to recruit them to help move the asteroid? Would the
behaviors or the goal structure necessarily change? Why or why not?

Exercise 8.4
Draw a FSA or write a script to coordinate the sequencing of the Pick Up the Trash
behaviors for Io, Ganymede, and Callisto.