Visual motion sensing onboard a 50-g helicopter flying freely under complex VICON-lighting conditions

In previous studies, we described how complicated tasks such as ground avoidance, terrain following, takeoff and landing can be performed using optic flow sensors mounted on a tethered flying robot called OCTAVE. In the present study, a new programmable visual motion sensor connected to a lightweight Bluetooth module was mounted on a free-flying 50-gram helicopter called TwinCoax. This small helicopter model equipped with 3 IR-reflective markers was flown in a dedicated room equipped with a VICON system to record its trajectory. The results of this study show that despite the complex, adverse lighting conditions, the optic flow measured onboard matched the ground-truth optic flow generated by the free-flying helicopter's trajectory quite exactly.