[yutsin1301]

It looks like LibrePilot has Android app to help the guy on the ground but that the flight stack software does not run on Android.  Is this correct?   

Does anyone know any open source pilot software where the Android device is the hardware for the pilot software?  There are smart watches (like LEMFO LEMX) now that run full Android OS and have GPS, gyros, compass, camera (8 mp), G4 communications, light (90 grams with watchband), rugged, low power, waterproof, cheap ($170), etc.  Seems like nice hardware for autopilot.     I realize that Android is not a real time OS, and so not at all ideal software environment for pilot software to run in.  But I think it might be made to work well enough.   Each year I expect better and better Android watches to come out.  So in the long run it seems like a good hardware platform to develop for.   Anyone got any pointers or advice?

[TheOtherCliff]

Correct.

I Googled for:
  android flight controller
and came up with some hits, but I would make a guess that they are not complete.

There are many, good FC's out there with more than GPS, gyros, and compass sensors (baro and telemetry come to mind), and having extra ports to connect to things like OSD (and telemetry and GPS because many FC's don't heve these built in).  These FC's cost $40 to $60 shipped, so $170 is not cheap when compared.  I also don't know if the watch sensors are up to the task.  For instance, the gyro sensors used generally handle 2000 degrees per second rotation, send updates 500 or more times a second, and can be trimmed to hold drift to just a few degrees in 60 seconds.  The GPS's we use send data in a special format so that you can say that THIS GPS update happened at exactly THIS time.  This is because the GPS data can come in several packets that take some time to receive.

LP was written assuming a multi-tasking executive, and there is a version that runs on Linux, but has the sensors commented out because there is not a standard device interface for them.  That is probably where I would start, but that is me.

Discussion has occurred in the past that it would be nice if the "next generation" was coded to run an RT flavor of Linux.  My opinion is that would be better than Android.

Good luck!