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I built a human-sized robot that can follow anyone wearing an IR beacon.

It works quite well indoors and it's quite precise, but outdoors it is completely blind due to sunlight infrared.

I have a bunch of XBee I can try to use to triangulate someone wearing an XBee as a beacon but I was wondering: What's the best way to make a robot follow you pretty much in every environment if you aren't more than 10 meters from it?

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A combination of the following: computer vision, an infrared beacon, lidar, radar, sonar, GPS, and physical tether. I kid, I kid. :D Tho it would likely be very accurate and on target. – horta Jun 19 '14 at 14:52
@horta: you forgot X-ray! – leftaroundabout Jun 19 '14 at 18:35
@leftaroundabout Ohhhh, good call. But in seriousness, Andy's answer is pretty awesome. I forgot that one of my buddies used that same technique to greatly enhance FTIR touch sensing sensitivity in his senior design project. – horta Jun 19 '14 at 18:42

Make your IR beacon transmit a square wave signal of a known frequency and make sure your receiver in the robot has a decent enough circuit to focus on the emitted IR known frequency.

If it turns out that your IR sensor is hitting the end stops in direct sunlight then change your sensor.

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This would work. IR remotes, for example, modulate their IR signals at about 38KHz. – sherrellbc Jun 19 '14 at 14:59

You could also add a high frequency (above human hearing) sonic beacon that it could follow.

It might drive the dogs crazy, but your robot will be able to follow it.

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I wonder if the robot might run into walls that the sound bounces off of. – horta Jun 19 '14 at 21:33

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