Some of you may have heard about SmartPlanes in Sweden. We have been quietly working with survey and mapping from UAV's for about 5 years now and keeping a bit of a low profile. I have just been putting a bit more information on our homepage about the kind of work we do and wanted to share it with you guys here at DiYDrones. I know a lot of you have ambitions of doing something commercial with UAV's in civilian applications and I'd be glad to share our experience.
Our plane was designed to be a portable system for aerial photography that can handle professional use in the field. We use a flying wing made out of covered EPP with vacuum formed polycarbonate fuselage that can be disassembled into 3 pieces for transport. It has an aft mounted electric motor and weighs about 1.1kg with camera and flys for about 35min on a 2500mAH flight pack. Our first version of this plane used a MicroPilot 2028g, now we use paparazzi autopilot. ask me why. It is hand-launch and manual landing. Flight planning is done by defining a single rotated rectangular block with dimensions and one waypoint. The actual navigation path is calculated in the autopilot code.
I think that aerial photography over small areas and single objects is a very good first civilian application for UAV's. We have seen a lot of interest in the technology, but the market is really undeveloped. For most mapping applications though, it is not enough to just take pictures from the air- you have to be able to generate a georeferenced photomosaic that you can use in a geographic information system. This is an area we have put a lot of effort into, within smartplanes and through some partners. We now have some software that allows you to create a good georeferenced mosaic already in the field on a laptop. For the more demanding applications that require true orthophotos and surface height models, we send the data in for processing.
We have found a lot of interest especially in making surface height measurements over small areas, because you can then measure volumes of things like gravel piles, sawdust, peat, rock aggregate, garbage, compost. Whatever people scoop up into big piles, they usually need to measure it and it is expensive to do it with conventional ground survey or aerial photography.
We normally cover an area of about 500x500m in a single flight because aviation regulations in most places require flying within line-of-sight. We can however join several flights into a large block for mapping larger areas. I think the largest block we have done to date had 30 blocks and almost 8000 photos. Very interesting to know it can be done, but at this size, laser scanning becomes more competetive.
Anyway I just want to tell you a little about our work and invite you to have a look at our homepage. Leave a comment here if you have any questions.
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Hi Steve!!
That is what I was doing this week ;)
Anyway, I will send you a PM.
Thanks for all again!
Mauro,
If you can control the length of time you apply the USB power from the autopilot, then you can use a camera script to measure this time and take different actions. Short pulse = take picture, long pulse = shutdown. Some clever people have even extended this idea to get a rudimentary serial communication with the camera. If you want more details, send me a PM.
As you use Canon cameras I assume you use CHDK.
I can trigger the camera via USB but I couldn't retract the lens.
Do you use a sript?
I will really appreciate if you can give me some tips on how did you do it.
Hope you can help me :)
Thanks!
Cropcam is actually Elektra PRO from topmodel.cz, it has enough wings and not enough fuselage capacity.
They use AXI 2820/10. you might go this way yet thsi is only sub-1h bird (significantly). But then, custom fuselage you rediscover all the details going on so I am afraid you might be very close to Pteryx concept and prices 1-4 years later it it has to really 'fly on demand'.
We are lazy and the disappointing remark is that we did barely enough for the job.
Twisting a digit left or righ won't help.
From 122m alt: with left - right viewing angle +/- 33deg from camera, 70m leg spacing is merely 47% side overlap, and occasionally 10-80% due to roll+wind. Not sufficient at all unless I made a gross mistake here, but it doesn't looks so, unfortunately. This 70% overlap is basically a REQUIREMENT for pro software. There is more, like they don't like overly trapezoid projections without saying how much.
Your numbers are slightly below my own. We were planning on 50m overall transect spacing after two flights of 100m track spacing, offset by 50m in each dimension. I re-evaluated the geometry and the capture speed, and I think it just might be plausible to do it in one 36km flight at 70m track spacing, though not for the Easy Star. Ours is pretty much packed full of batteries at this point, and landing is a nontrivial challenge - we're going to need a bird with flaps. My feeling is that the Skywalker, Super Easy Fly, or Diamond 2500 *might* work after the right optimizations. After that, we would probably either need custom foam (not a skill in our repertoire yet) or a composite built-up plane. Fragile landings are something we're trying hard to avoid.
I don't know yet whether 70m spacing is sufficient for reliability on highly complex geometry - I suspect not, for the more conservative software packages.
Outside of my team, I've been keeping an eye out for techs that might help us. Solar panels and autonomous thermal gliding would be very interesting to pursue later on. Parachute landing, I know your feelings on, and I think it might be viable eventually for us. A very small brushless motor powering a large prop through a gearbox at 75% throttle seems to be ideal for level flight, but for launch much more power is needed, so a fall-off booster pack may be a good idea in place of a high start. I'm particularly interested in slow-rotating twin prop, twin boom systems rather than fast-rotating pusher props.
Most likely, though, we'll be looking for an OTS sailplane airframe that is several hundred dollars, stuffing a bunch of batteries in it, and hoping we can make it perform anywhere near works of art like the Pteryx, which is regrettably far out of our budget.
After the Octocopter :)
The blur in GW demo? It could be anything, including too long exposition time (any clues about the numbers in that case?).
I believe all this shaking is inevitable to some degree with smaller platform (including estars). We have some oscillation in turbulent weather even on Pteryx UAV, this is why we have stabilized head (the bird is more stable than any stock ARF and yet we had to stabilize it more for guaranteed overlap).
From 122m agl (400ft) you are in a difficult situation.
'Balanced, typical' 75% side overlap requires 33m leg spacing IF you have stabilised head or ideal weather...
Suppose you have it:
1km^2 is 30 legs 1km each. 30km of flying PLUS turns and other business, you get easily into 40km trip.
This would be 1h job for the easystar would it be able to do it. But int with the wind blowing, then you have to account some extra 3m/s and even longer, say 1h30 flight time.
1h30 is RECORD flight with easystars fully laden with battery, no camera (and not with just any autopilot). Same for cularis etc. Basically for any decent surface you are quickly finding there is no easy way, unless you want to map 400m by 400m, only then it is feasible with stock models with typical weather (not one-time weekend show).
The best way for surface coverage is to get as much altitude as you can (200-400m), when the laws allow.
Hi Steve!
Nice to hear from you!
I believe that I know what you say with the motion blur on heavy and fast planes
Here you can see a demo that Gatewing did in Chile last month... see it in max resolution to see the "out of focus"
that plane weights about 2kg and its very fast
http://img685.imageshack.us/i/clubdegolf1.jpg/
About the flight time... I think that you can get that autonomy only with hitech motors like Mega's, not with the chinesse ones we are using! lol
Did you try using two batteries to get aprox one hour of flight time?? Or the extra weight its a problem?
That is the time we want to achieve ;)
Thanks for sharing!
Hi Mauro, we use a relatively small prop 7X5E. With about a 1500kv brushless motor and 3 cells it gives a nice speed range and efficient cruise with only 40% throttle.
Squalish- Yes I feel 400ft is on the low end for this type of work. You really want to plan for 70-80% photo overlap for best results and that makes for many strips and fast camera intervals at 400ft. It is really the relative difference in terrain height (or height of ground objects) vs the flying height that is important, so for flat agricultural land you can get away with less overlap. We normally like to operate from 600-900ft or so which makes for fewer flight strips and fewer photos per block to process. Luckily we have a set of regulations here that allows for it.
As for stability in the wind, a flying wing with almost neutral stability does tend to be less sensitive to gusts. The other approach is to fly faster with more wing loading but then you might run into problems with making tight turns and motion blur. And again if you can fly higher, the wind tends to be smoother.
Thanks for the interest and good luck with your project!
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