Stupid Magnetism!

In this week’s installment, we learn how an I-beam, a squat cage and a freestanding heavy-bag frame down in the basement can cause problems for a robot driving around on the first floor.

After this weekend’s successful test drive of the Escalade rover, I wanted to fine-tune the control system by calibrating the compass and associated steering algorithm.  I *thought* that I would be able to do that inside since I only need 15 feet or so to drive in a straight line.  Unfortunately, I was getting very inconsistent results.  Eventually I realized what was causing the problem.


My basement has some very large steel objects in it.  Every time the robot drives over one of them, the internal compass would start getting weird results.  Then the steering system would go nuts and the rover would crash into something.  At first I was doubtful but then I realized that the straight line distance from the first floor to the ceiling of the basement is less than a foot.  Apparently, the “magnetometer on a chip” is sensitive enough that those things throw it off.

It was good to realize what was happening but that slows down my progress if I can’t test inside.  The temperature outside right now is -1 F.  Sure, I’m a manly man and not scared of a little frostbite but the cold is bad for the batteries.  So I think I will turn on an episode of Mythbusters and call it a night.  

Stupid magnetism.


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