Pixhawk (PX4)

PX4FMU is a high-performance autopilot-on-module suitable for fixed wing, multi rotors, helicopters, cars, boats and any other robotic platform that can move. It is targeted towards high-end research, amateur and industry needs.  Any multicopter / airplane / rover or boat that can be controlled with normal RC servos or Futaba S-Bus servos (S-Bus or servos: only in combination with PX4IO Airplane/Rover Servo and I/O Module, brushless motors controllers can be controlled with PX4FMU alone, up to four in a classic quadrotor setup.)

The PX4FMU autopilot module runs a very efficient real-time operating system (RTOS), which provides a POSIX-style environment (i.e. printf(), pthreads, /dev/ttyS1, open(), write(), poll(), ioctl(), etc). The software can be updated with an USB bootloader. PX4 communicates to ground control stations via MAVLink and can be operated with QGroundControl and APM Planner. All software is open-source and BSD licensed.