wxyz
Senior Heliman
Location: calif*, U know where
| The autopilot itself using 1Hz code phase GPS is only $600 of parts. A more reliable 20Hz carrier phase GPS would bring you to $900. The cost of crashes, batteries, airframes is $1,000,000,000,000,000,000,000,000.000. It is the calibration & work you do yourself, not the stuff you buy, that is the main problem.
From the VicaCopter manual which is a work in progress:
**** Magnetometer calibration
The IMU must be calibrated and giving the proper roll & pitch before the
magnetometer is calibrated.
In settings.conf, set X_MAG, Y_MAG, Z_MAG to 0, 1, 2. Set DUMP_MAG to
1. Set DECLINATION to 0.
Run the autopilot on the airframe with the magnetometer & everything
mounted in its final position. Rotate the airframe on the X, Y, & Z
axes and note which axis corresponds to which column of mag output.
Change the X_MAG, Y_MAG, & Z_MAG indices to match the dumped columns.
Now the X, Y, & Z axes will be dumped in order & it's time to calibrate
the ranges.
Rotate on the X, Y, & Z axes and note which direction North is from the
printout. Unless you're on the equator, north points into the ground or
into the sky.
Point each axis of the magnetometer towards & away from North and copy
the max & min values from each column to the MAG_MIN and MAG_MAX values
in settings.conf. Next, set DUMP_MAG to 0 and DUMP_THETA to 1.
With the autopilot running, rotate the airframe on the yaw axis. The
printed heading should be North: 0, East: 90, South -179/179, West: -90.
If the heading increases when it should decrease, reverse COMPASS_SIGN
in settings.conf. If the heading is always offset by a certain amount,
change COMPASS_OFFSET in settings.conf to correct the offset.
Finally, you need to set DECLINATION to the magnetic declination for
your area. If magnetic north is 14' East of true north, set DECLINATION
to 14.
With the autopilot running, rotate on the yaw & pitch axes to verify the
compass reading is mostly independant of the attitude. |
