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U.S. Department of Energy
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Geometric considerations for a waypoint guidance method

Technical Report ·
DOI:https://doi.org/10.2172/5425178· OSTI ID:5425178
Waypoint guidance is a technique used to steer an autonomous vehicle along a desired course. Waypoints are designated at intervals along that course. The guidance algorithms issue steering commands that, if followed, result in the vehicle's traveling from waypoint to waypoint. Thus, the vehicle remains on or very close to the desired trajectory. Waypoints can be specified by latitude, longitude, and altitude in geographic coordinates. The vehicle's current location can be described similarly. This is enough information to determine the direction of travel that would take the vehicle to the waypoint. The shortest route from one point on a spherical surface to another on the same surface is a great circle. A great circle lies in a plane that contains the center of the sphere. The plane also is normal to the surface of the sphere along the great circle. The earth actually is distorted slightly from spherical; it is ellipsoidal. An ellipsoidal earth model will be used in this report. Features of the great circle will be applied to effect good approximations of shortest routes to waypoints. Therefore, only the endpoints of long, straight course segments need be specified. 5 figs.
Research Organization:
Sandia National Labs., Albuquerque, NM (USA)
Sponsoring Organization:
DOE/DP
DOE Contract Number:
AC04-76DP00789
OSTI ID:
5425178
Report Number(s):
SAND-89-0623; ON: DE90001803
Country of Publication:
United States
Language:
English