I'm currently building an Alien 680 Frame and looking around for ideas on mounting the ESC's, FC etc., I noticed several using xHawks and they mount it inside the frame with the power wires surrounding it underneath the frame.
I've always mounted the Pixhawk et al on top of the frame well above the power wires. How are these guys flying without compass issues with the FC sandwiched inside the frame right above the power wires?
Are they not doing compassmot or something? Their copters seem to fly quite well. It seems the EKF would be doing somersaults.
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Bottom line: If the parameter is set to external compass, the internal compass is NEVER used.
That is where the confusion on my end arose. A few months back I had a flyaway with the test quad and posted in the 3.3 beta thread. Randy suggested moving the compass further away from the power wire. I took that as moving the internal compass because the external is a good 6-8" above the power wires, and the case is all plastic including the screws/nuts. So I installed a vibration dampener which did raise the FC up higher; not a total waste because vibration levels are now near non-existent.
The flyway is still a mystery, but Randy did come back and mention the AUAV-X2 FC had a hardware bug to be fixed via software in a later 3.3 rc. I ended up grounding the quad until it was fixed because there was no logical explanation for the flyaway, at least from my perspective. Since the fix, EKF monitors and all other data show no problems.
Regardless, I had thought when doing compass calibration it included the internal compass in the process. Wow, did I have this totally misunderstood.......after over 1 1/2 years. I thought it was important to keep the Pixhawk far away from power wires, yet continually saw setups with it buried inside the frame and wondered how they weren't causing flight issues.
Alrighty then, inside the frame it goes. Thanks all. BTW, this FC is a CUAV Pixhack for something different to try out.
I'd nearly always recommend using an external compass instead of trying to rely on the internal one. Nearby power wires definitely sounds bad to me!
Hi Randy,
I was debugging a compass inconsistent issue on Plane 3.5, and eventually got it working after a 3rd full compass calibration (on pixhawk).
However, before that, I just had to disable the internal compass or I was not able to arm (the external compass felt more trustworthy) (COMPASS1_USE1 0)
But then I came to wonder, is there even a good reason to use the internal compass that is so close to so many wires and sources of interference? Any reason to not just disable that compass forever?
Thanks.