Robot Positioning Systems?

CyberLeader asks: "As a hobby I've been developing a small robot to mow the lawn (giving me more precious hours to read Slashdot, of course). The intended brain of the 'bot is a small Linux-based on-board PC. To be able to operate the 'bot as desired, the PC needs to be able to accurately identify the robot's location to within about 10 centimeters, but I can't find any decent system to do this that falls within my cost constraints of a few hundred U.S. dollars. The position doesn't have to be global; it can be relative to radio beacons or similar devices placed around the yard. Any suggestions?" Ah, the mischeif I could have caused if I had had one of these as a teenager...

Comments

Just use your eyes, and don't void your insurance

[unitron]

Since you have absolutely no business whatsoever allowing something like this to operate unattended, you might as well just go with plain ol' wireless remote control and get any necessary guidance information with your eyes.

I'd say something about Cliff having misspelled mischief, but that would just about guarantee that I'd misspelled guidance.

Spinning laser beacon.

[Matt_Bennett]

At a place I used to work, used a system developed by MacLeod Technologies, the CONAC System. They used to have a web page, but I can't find it. Very small company, snd I don't know if they are in buisness anymore. Here's a PDF that has a bit of a description. A google search on CONAC gets a few more hits. It is very accurate over a limited area like a yard- it works like this: Spin a laser that has a somewhat fan shaped beam, with the axis of the fan vertical, and sweeping 360 degrees of azimuth. Place (laser) recievers at known, fixed locations around the perimeter of the area. When the laser sweeps over a beacon, record the time. The time betwwen each reciever responding will give you azimuth to each reciver. If you have a reciever on the robot itself, you know which direction your robot is pointing, in relation to the array of recievers. With all this information, you can derive position and azimuth of your robot.

Make sure you have >> 3 recievers so you can have an overdetermined solution, so that if one reciever is blocked by a person, tree, or errant butterfly, you can still determine the position.

This *does* work, as long as you don't get too far from the sensors. The farther the sensor is away, the less accurate the position solution. You might want to implement multiple sorts of sensors, including compass and whatever else you can, and feed them all as inputs to a Kalman filter, which should give you a more robust solution.

If you'd like to talk about this, de-obfuscate, and drop me an email. I'd love to have a system like this for my *own* lawn.