Give your gizmo the gift of sight
The Position hold capability is when the hovering air vehicle remains roughly over the same location with low drift over time, even with some wind. It is very useful on almost all hovering vehicles on anything other than a completely calm day. It is useful when GPS is unavailable or poor (>8m wander).
The Parrot AR.Drone2 is a large consumer quad air vehicle weighing hundreds of grams. It has position hold based on optical flow using a 160x120 pixel downward camera, a chunky 1 GHz ARM processor/DSP, state of the art image processing algorithms, fusion with the IMU. Its' position hold system works well outdoors in most circumstances.
My interest is in nano air vehicles weighing tens of grams that cannot afford the weight and power consumption of the Parrot optical flow solution.
We already have the IMU and the ability to fuse the optical flow (OF) stream. We need an off the shelf OF sensor which works pretty well with the following ideal spec:
sensor mounted to point vertically downwards;outdoor operation; all types of ground (grass, sand, fields, scrub, urban concrete, stone, tarmac); low-contrast and high-contrast ambient illumination; moonlight (0.1 Lux) and full sunlight illumination levels; <0.5g weight; <6x6mm in size; processing built-in; X pixel velocity, Y pixel velocity OF outputs; OF output rate >=60 Hz; XY drift <6 m/min when integrated position hold system is performing well with wind speed ~5 mph; a standard interface as found on any microcontroller; robustly packaged as a SOC product; surface mount; plug-in EVB evaluation board on USB-2 running under Windows with simple mouse click controls, display and CSV output to file for post-analysis.
Meanwhile, what should we buy that Centeye have for evaluating in this position hold application with the least amount of engineering input at our end?