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.

Steel

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.

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s