Don Carveth of botgoodies.com
has written an article
comparing the PNI
Corp Vector 2X and Dinsmore 1655
electronic compass modules and showing how to interface them to an Atmel
ATMEGA163 microcontroller programmed using GCC. The article includes
schematics, photos, C code, and test results showing the accuracy
achieved with each of the two sensors.
I was surprised the Dinsmore won out both in price and accuracy and
size. At any rate, it seems that a robot can only use the direction
as a wild confirmation against other sensors and orientation knowledge
that your bot is going in a certain direction. IE: You really
couldn't rely on the compass readings much for dead reckoning. I'm
thinking that a robot that's trying to navigate a house would use
either wall following methods or dead reckoning and use the compass
just to confirm that a turn actually worked or not rather than to know
an exact degrees it's facing. Is there anyone who's really relying on
the compass as a primary means of direction indicator rather than
secondary indicator? If secondary, is it really even necessary? :-/
Considering that a much more sophisticated and accurate technology like
GPS (providing absolute positionning) does not even perform correctly
indoor, I guess you sum it up: "use the compass just to confirm that a
turn actually worked or
Nevertheless even as a secondary indicator I'd like to hear about the
results, since I plan to use one myself.
BTW this also bring the question of the "what for" of these electronic
compasses in the first place (outside the hobbyist robotic field):
regular old-fashioned compass are much cheaper and perform better. So
cool gyzmos, but what's the market?
I was going to rely heavily on a compass for directional control..
Already have the dinsmore (on the shelf and untested as of yet) and am
dissapointed to see the reviewer make note of hysteresis problems. The
product description said there was protection here so I had hoped to
avoid this kind of thing entirely.
I wonder what a guy could do with a pocket compass drilled for
infrared/phototransistor pairs or a large liquid filled compass with
some type of encoder marks?