>maybe ultrasound or IR beacons?
If we used IR beacons and triangulation 3cm at 50m would
require an angular resolution of 0.035 degrees
Inv sin(.03/50). Doable but not for under 500$
Would we need 3cm resolution? If we could get it we would
not need any other kind of navigation which would be nice.
But, How about say 1m resolution and suppliment it with
near field sensing and navigation. Use the navigation
beacons to get close and nearfield landmarks to tune us in.
1M resolution would only require 1degree resolution which
can be done on the cheep. The accuracy could be improved
if we were willing to use many IR beacons. This would bring
up potiential problems with cost and maintenance or the
beacons.
Ron