I made a very crude prototype adding a second axis gimbal to the DJI Phantom 2 Vision. Here are some pics, I used an old very cheap servo motor but the proof of concept is in the pudding. I also need to add a second support pivot near the front, currently the entire camera is supported by the servo motor output shaft. A higher quality servo with ball bearings and possibly brushless servo would be ideal.
And here is a quick video showing the shaky performance, lowering the gain makes it run too slow, also note that the pitch servo is also slow, needs more gain — currently set to fifty but at sixty it overshoots. The roll servo gain is set to thirty. (sorry for the dirty bachelor pad mirror)
There were no modifications to the Phantom 2 itself, other than repositioning the video cable to allow for the lower position of the camera, and also extended landing gear are necessary since the camera hangs below the stock landing gear, I think I saw a pair on the web for about ten bucks. The roll servo was simply plugged into the NAZA-M (V2) Main Controller, plug and play baby! Although if you wish to control the pitch servo gain the NAZA mode must be used, no big deal.
For those of you who wish to know I measured the pulse width of the pitch servo control signal, centered and level was 1.53 ms, tilted right 90 degrees was 2.10 ms, tilted full left was 0.991 ms.