just want to highlight our most recent developments on PenguPilot, a GNU/Linux based Multi-Rotor UAV Autopilot.
A Video with horizontal GPS position stabilization and vertical ultrasonic stabilization is avaliable here:
The whole control process is implemented in C under Linux (PREEMPT Kernel). The latest source code is available here:
IPC among C and Python processes is implemented via ZeroMQ and MessagePack/Protobuf.