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Unread 27-09-2007, 23:22
Gdeaver Gdeaver is online now
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Re: Programming a Devantech Magnetic Compass - CMPS03

Interfacing a digital compass is a good project. However, after you master the compass you may not find it meets your needs. These devices measure the earths magnetic field in 2 axis and can give orientation. The problem is a FRC robot usually has some ferrous metal in it and our motors have some big powerful magnets in them. Even if you mounted the compass far away from these fields, they will affect them. You can calibrate for hard iron effects but the margin of error is going to be less than desirable. I played with a PNI VX2e and the best I could get with a FRC robot environment was +- 5 degrees. That was with out the motors running. If another robot is near you and it has allot of ferrous metal, The compass is going to get real bad. I have given up on digital compasses for FRC uses. For the tele-operated part of the match the organic analog computer- sensor network between the drivers ears may be your best bet for detecting the robots orientation. Don't give up though. The skills you learn for the compass have other applications for our robots.