In the domain of UAV swarming, many experimental set-ups may require at the same time accuracy and reliability of an off-the-shelf autopilot, plus some extra computational power that those autopilots cannot (yet) provide. If the experiment can be made cost-efficient, that would be even better. Those are currently my own user requirements, and I therefore would like to easily interconnect a Raspberry Pi and a regular autopilot (preferably Arduino-based, but any other combination is worth considering too) to steer a multi-copter and perform some computational intensive jobs such as computer vision.

I am currently in the early stages of testing an APM 2.6 + Raspberry Pi combination, notably following the following design guidelines: http://dev.ardupilot.com/wiki/companion-computers/raspberry-pi-via-mavlink/ (well, this tutorial is intended for Pixhawk autopilots but using MAVLink w/ APM should be ok too).

Now, I would be grateful for any practical return of experience about this combination or any other Raspberry/autopilot dual layout, to be able to consider other design approaches if that one failed. I also heard about Raspberry shields like Navio/Navio+ but I did not yet find backed up opinions about the ability of such set-ups to correctly deal with the stringent constraints of real-time for a multi-copter design. So here again, any practical experience on the subject will be greatly appreciated!