Note #23 - Top-level control

	For participants only. Not for public distribution.
	Note #23 Top-level control John Nagle Last revised May 11, 2003.

DRAFT

Driving control is generally in one of the following states:

State	Actions
Road following	Maps indicate that a road should be in the area and going towards the next waypoint. Road follower has primary control.
Road search	Maps indicate that a road should be in the area and going towards the next waypoint, but road follower does not see a road. Off-road driving control is primary, with the goal direction changing so that the vehicle executes a search pattern of shallow S-turns generally heading towards the next waypoint.
Off road	Maps do not indicate a usable road in the area. Off-road driving control is able to move towards the next waypoint without encountering a major obstacle.
Maze solving	An obstacle has been encountered that cannot be easily bypassed. A simple path-planning algorithm like A* is used to try to get out of the problem.
Stationary mapping	The vehicle is stopped, and steerable sensors are used to build up as much map information as possible.
Stopped	The vehicle is stopped and not doing anything.