Page 136 - Designing Autonomous Mobile Robots : Inside the Mindo f an Intellegent Machine
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Live Reckoning
Target
IP
Right
Left
Left
Right
Figure 8.1. The “Crooked Leg” navigation system
In navigation terms, the first beams gave the pilot absolute information about the air-
craft’s lateral position with respect to its intended path, but told nothing about the
longitudinal position along the path. The longitudinal position was estimated en route
from air speed and wind reports. The second beams provided the longitudinal correc-
tion or longitudinal fix. These basic concepts are the same as those of mobile robot
navigation, which in turn are the same as those used by animals for navigation.
One of the very few absolute navigational references available is the GPS (Global
Positioning System). This system provides very accurate absolute position informa-
tion by triangulating satellite signals. Best of all, it requires only an inexpensive GPS
receiver.
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