Clayton, I've been experimenting with 9-DOF boards for a custom AZ/EL rotator and controller build I'm doing. DOF chips require filtering to reduce the noise levels of the raw data and to calculate a heading. Even with filtering, the values tend to bounce around a lot, by more than a few degrees. They also need to be calibrated by moving them around. Obviously this is an issue when it's mounted to a rotator as you can't easily move it around when powering it up. Some DOF libraries will allow calibration data to be saved and re-applied after restart. The noisy data and processing required for the filters has been the main issues for me.
I just received this one from Adafruit - https://www.adafruit.com/products/2472
It has an onboard processor that filters the raw data and returns absolute position in degrees, with no math on the Arduino and no bouncy readings. Once the board is calibrated and the calibration setting saved, it's just a matter of loading the saved calibrations when the board powers up.
I haven't had this board long enough to determine how well it will work long term, but so far I've been impressed with it's noiseless and consistent readings over many restarts. It even returns a consistent compass heading when it's pointing north and it's rotated 90 degrees along the E/W axis.. The previous board I tried didn't do so well for compass readings when the board wasn't flat. My plan is to use this to calculate compass and elevation from it's boom mounted position for initial rotator zeroing and as a secondary sensor for sanity checking AZ/EL positions.
Steve KD8QWT
On Thu, Feb 18, 2016 at 1:58 PM, Clayton W5PFG w5pfg@amsat.org wrote:
Has anyone ever mounted a mutli-axis accelerometer or a magnetic compass sensor to their antenna crossboom for making adjustments to point of aim?
I'm currently using Hall Effect sensors but experiencing several degrees of drift over a short period of a few days.
73 Clayton W5PFG
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