6 Jun 2006 cschur   » (Master)

Here is a progress report on the Geobot. The devantech compass is finally working, the unit we got simply would not calibrate for blood or money. We rotated it in the cal mode over and over, but the cal done lamp would not change. Finally, in desparation, we calibrated it using the old style previous rev software version method. It worked. Apparently, we got an unmarked chip, which was not the newest version.

Anyway, The robot now goes out a preset distance, rotates 180, and returns very near the start position. We are ready to add the arm now, that will collect the rock samples from the remote location and return with them.

So two problems we encountered this week are first, the tank base I used (Stuart M5) doesnt have the power to rotate in place on 3 inch deep grass. We stick to rocky flats for now. Second, the motors genrate a horrendous magnetic field from the magnets inside them, which cause up to 20 degree offsets at certain angles from the real bearing!

WEll, other than mount the darn compass on a six foot pole, Im going to try to keep missions on the NS - EW line for now, thats where the compass is calibrated to be dead on. Alternately, I can make some sort of look up table for each angle as to what angle really is 180 degrees so It turns around at its destination for the return trip.

The final goal of course will be to send the robot on a rocky gravely plain (common here in Arizona) out to 100 foot distance, collect surface specimens with a motorized scoop with a rotating brush on the end, and return them to the start point.

The project page for the Geobot is at:

http://www.schursastrophotography.com/robotics/geobot_mainpa ge.html

Write me if you have time! chris


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