The APM is an open source project from 3DRobotics. It began life as the Ardupilot, a fixed wing flight control system based on the Arduino. The project quickly grew to include rovers, helicopters ...
Two of the most popular are ArduPilot and PX4 ... autopilot module and a Dragonlink telemetry link to the ground control laptop. Initial testing was unsuccessful, with the drone ignoring return ...