### Author Topic: Moving beacons  (Read 2067 times)

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#### snak

• Beginner
• Posts: 1
##### Moving beacons
« on: September 26, 2007, 01:04:02 PM »
I had an idea a bit ago and am curious to hear if it has been tried, etc.

Assume you have three beacons and a single robot.  The beacons start around the robot, exactly where isn't too important.  The robot navigates about, doing whatever it needs to do.  When the robot reaches the limit of a beacon, either because of range issues or because of obstruction, it picks up one of the three beacons and places it somewhere else in the direction it wants to go.  By triangulating off of the two unmoved beacons the robot can know pretty exactly where the third beacon is now located.  This process can be repeated indefinitely.  The benefit is that the robot can at any time determine it's own location with great accuracy, yet the area to be explored does not need to be pre-seeded with beacons.  The major objection I forsee is the inefficiency involved in constantly repositioning beacons.

Sort of like the great great trignometrical survey writ small
(http://www.thegreatarc.net/)

• Supreme Robot
• Posts: 11,680
##### Re: Moving beacons
« Reply #1 on: September 29, 2007, 01:44:59 PM »
Quote
By triangulating off of the two unmoved beacons the robot can know pretty exactly where the third beacon is now located.
Did you just say 'triangulating off of the two' beacons? You need at least three to triangulate

Actually, triagulation only works if you have a perfectly flat world. You would need four beacons for 3D terrain. Then a 5th to move around so that you have at least four that are stationary at all times.

I think the biggest problem with this is:
A) robot needs to decide where to move the beacons intelligently
B) moving 5 beacons means the robot needs to move back and forth 5 times, resulting in 10 times the distance needed to travel (both ways)

I think a better method would be to identify landmarks in the path, and change landmarks as the robot progresses. This is how humans navigate.