Page 413 - Introduction to AI Robotics

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Localization and Map Making
11

Figure 11.8 CARMEL at the 1992 AAAI Mobile Robot Competition. (Photograph
courtesy of David Kortenkamp and AAAI.)

can be represented by a byte, rather than a structure containing at least two
floating point numbers.
The sonar model also shows the updating rule. In HIMM, the l are incre-
mented with I each time the acoustic axis of a sonar reading passes over it.
If an l is empty, the increment I is -1. Occupied l is incremented with I =+3.
This implies that HIMM believes a region is occupied more than it believes
the intervening regions are empty; this is the opposite of evidential meth-
ods. The update rule also is computationally efficient; it reduces scoring to
addition and subtraction of integers, which takes far fewer CPU clock cycles
to execute than multiplication and division of floating point numbers. The