Data Implementation 
The terrain data base will be fulfilling several operational roles. 
Besides providing a-priori terrain information for road following and 
pre-mission route planning, it will be supporting the perception, or 
visual, subsystem for obstacle recognition/ avoidance and landmark 
recognition. A simplified version of the system architecture is dep- 
icted in Figure 2. 
TERRAIN————— TERRAIN ¢———3 PERCEPTION 
DATA BASE KNOWLEDGE BASE 
LANDMARK 
RECOGNITION 
i 
MISSION .— ———, REASONING (— ———— POSITIONAL 
GOALS KNOWLEDGE 
  
ROUTE PLAN/ 
EXECUTION 
FIGURE 2. General system architecture. 
The terrain data base is incorporated into a terrain knowledge base sub- 
system as the a-priori information source. During pre-mission route 
planning, the terrain knowledge base is queried by the reasoning subsys- 
tem which functions to determine the most cost-effective route to get 
from point A to point B. Several researchers have proposed using an 
optimization factor referred to as a figure-of-merit (FOM) which is cal- 
culated by estimating the probable cost of traversing small unit areas 
within the terrain (Linden, 1986). Starting at point A, rules are used 
to determine the traversability of various terrain features along a 
potential route to point B. If an impassable feature is encountered, the 
reasoning subsystem will determine a route around the feature while 
keeping the ultimate mission goal, arrival at point B, as the main 
objective. It should be stressed that information from all terrain 
themes will be considered in the route planning process. As a result, it 
may find an obstacle in one overlay while not in the others. Thus, it 
is crucial that the reasoning system identify and evaluate such con- 
flicts in the terrain knowledge base in order to arrive at the most 
efficable decision. 
Once the pre-mission route plan has been determined, the vehicle will 
482 
  
  
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