2018-01-08, 11:23 PM
(This post was last modified: 2018-01-08, 11:26 PM by seandepagnier.)
Logically it makes sense to move the sensors away, but until someone can demonstrate that there is a significant improvement, I am not convinced it is worthwhile.
I have done plenty of testing with the imu directly above the raspberry and the compass is good enough. Keep in mind, the kalman filter uses the gyros and the compass essentially corrects for gyro drift. The autocalibration routines correct for distortions around the compass.
The only thing I can think of that would cause problems is stray magnetic fields, but I cannot find any. Do the switching regulators emit enough interference to make a measurable increase in noise??
The easiest way to test would be to run the scope from the compass tab. Check the "imu.compass" sensors, and watch them, and look at the noise levels. This would be best to do on land, or on a stationary platform, not a boat swinging at anchor. I tried this and didn't notice any significant difference when moving the sensors around.
I did measure a difference if the wires going to an electric motor (wires that carry more than 1 amp) are within a few cm of the sensors. If you had an external hard spinning drive near the raspberry, or usb devices that draw a lot of current it could potentially cause problems.
Temperature sensors are different, they will obviously give a false reading as the raspberry generates quite a few degrees of heat above ambient in most cases.
I have done plenty of testing with the imu directly above the raspberry and the compass is good enough. Keep in mind, the kalman filter uses the gyros and the compass essentially corrects for gyro drift. The autocalibration routines correct for distortions around the compass.
The only thing I can think of that would cause problems is stray magnetic fields, but I cannot find any. Do the switching regulators emit enough interference to make a measurable increase in noise??
The easiest way to test would be to run the scope from the compass tab. Check the "imu.compass" sensors, and watch them, and look at the noise levels. This would be best to do on land, or on a stationary platform, not a boat swinging at anchor. I tried this and didn't notice any significant difference when moving the sensors around.
I did measure a difference if the wires going to an electric motor (wires that carry more than 1 amp) are within a few cm of the sensors. If you had an external hard spinning drive near the raspberry, or usb devices that draw a lot of current it could potentially cause problems.
Temperature sensors are different, they will obviously give a false reading as the raspberry generates quite a few degrees of heat above ambient in most cases.