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FUTURE AUTOMOTIVE ELECTRONIC SYSTEMS 11

RAM as desired for a particular trip. Alternatively, a CD (compact disc)
player could be used for large-scale data storage. In this case, the CD player
would be part of the entertainment system. If the vehicle electronic system is
integrated, the CD player can function as a large-scale memory for on-board
navigation data.
The computer portion of the generic navigation system obtains signals
from various position sensors and calculates the correct vehicle position in
relationship to the map coordinates. The computer also controls the map
display, accounting for magnification (called for by the driver) and displaying
the vehicle position superimposed on the map. The correct vehicle position
might, for example, be shown as a flashing bright spot.

Navigation Sensors
The most critical and costly component in the generic navigation system
is the position-determining system, that is, the position sensor. Among the
concepts presently being considered for automotive navigation are inertial
navigation, radio navigation, signpost navigation, and dead reckoning
navigation. Each of these has relative advantages in terms of cost and
performance.
An inertial navigation sensor has been developed for aircraft navigation,
but it is relatively expensive. The aircraft inertial navigation sensor consists of
three gyros and accelerometers. Figure 11.19 is a block diagram of a typical
navigation system using inertial navigation.

Figure 11.19
Automotive Inertial
Navigation System

FPO

UNDERSTANDING AUTOMOTIVE ELECTRONICS 393