I am involved a project that requires capturing aerial imagery for the purpose of generating overhead maps of a relatively small ( < 1 x 1 km) archaeological site. We're quad/hex/octo-rotor setups, and balloon based solutions for gathering this imagery. The goal is to gather the imagery in an autonomous fashion by developing a relatively simple flight plan (a survey of a polygonal area, or perhaps even waypoint-to-waypoint flight).
The problem is that the site is located approximately 4500 m asl, which has caused difficulties launching and flying small RC/autonomous planes in the past. Due to previous difficulties with planes, we're considering blimp and copter based solutions. The vehicle would need to fly 40 - 100m above ground level. Winds at the site are typically non-existent during the time of year we will be flying, so I don't forsee high winds being an issue. In addition to the craft itself, it would need to carry ~ 300 - 350 g payload (e.g., camera, mounting hardware, etc.). Battery life should be at or better than 20 minutes.
Here are my questions:
1) I think a balloon-based approach is possible here. I could use the ArduPilot Mega for on-bard sensing and control (I think), but how much modification would need to be made to the autopilot software to successfully control the blimp? Any ideas? I'm not averse to software whatsoever, and have developed extensively in C++ (and in Processing/Wiring for Arduino work) for a number of years.
2) If a balloon is possible, can anyone point me to a resource that would allow me to calculate the needed volume of the balloon? Any recommendations for how to construct the balloon?
3) I can't seem to find an off the self solution, in either a blimp or a copter, that will achieve our goals, or at least achieve them with limited modification. Does anyone know of anything available for purchase (within a reasonable cost < $2500) that can serve as a good starting point for modification or end solution?
Thanks!
Replies
Anecdote: I got 10 minutes on a coaxial octocopter carring 800 gram payload + 400 gram battery when the air pressure was 0.64 atm (Mt Erebus). 10x4.5 props, xaircraft x650v8 with APM2.
I also have been working on a quad to do archaeo survey and general mapping. While all of my initial testing was done at sea level I operated it this past week around 6,000' ASL and didn't notice any issues. I get around 9 minutes per battery set though. Your criteria of 20 minutes, with payload, would be very difficult to meet with a multirotor.
While a multirotor is good for smaller or well defined sites, I am also constructing a Techpod for mapping large areas (I considered a Skywalker as they are good planes but decided the Techpod offered superior payload options). The Techpod is very new, relatively large fixed wing aircraft expressly designed to carry FPV gear and imaging payloads. 2 hour flights with payload have been demonstrated. There would be absolutely no issues with the altitude you mention.
The designer of the Techpod sells them at hobbyuav.com. You would be well under your budget if you went this route, and you'd be able to loft a couple of kilograms instead of .3 to .35 Kg.
hi you could use a plane as the skywalker equipped with APM 2.5, the skywalker has good lift and buoyancy force. you can build for less than 2500, you can install a samsumg nx200 camera, I use it with good results.
these are some of my work with skywalker ralizados 1900
http://diydrones.com/profiles/blogs/apm-2-5-for-photogrammetry
more info
http://www.makedrones.com/