We have been working to develop a well oiled solution for Aerial Survey and Photogrammetry over the last few moths. While there are a number of off the shelf solutions out there which produce great results, we are looking for something that will cover larger areas at a higher resolution. We started with the X5 as it could be hand launched and was a good platform that flew at higher airspeeds and could progress us into the X7. Here is some of our progress;
The X5 is running on APM 2.6 and has prove extremely reliable and stable. The camera used is a canon IXUS 132 running CHDK and shooting on an intervalometer script. The main purpose of the X5 was to learn about vibration dampenning and apature and ISO settigs to produce clear images. This took a significant amount of effort, however we are at the stage where 2 out of 3 images are photogrammetry quailty.
Our test baby has had a few hard landings (things were laid out a little neater when we started) . We are very excited about the recent interest and work being done on laser altimetry in recent months. We are also currently testing one of these devices as flying wings are extremely hard to land manually (especially when they are loaded up with gear). You can see the APM in the middle of the plane, 5.8GHz live video and 900MHz telemetry transmitters, and the IXUS 132.
We found the X5 reasonably easy to hand launch WITH A WELDING GLOVE (it will cut your hand to shreds - not if...when). You can see the camera poking out of the front of the plane. Images are good, however, to get the plane to navigate the survey grid well, it becomes a little twitchy which means that a high number of the images are not taken pointing straight down. Navigation accuracy (Nav Constants and Pitch and Roll constants) v's image quality is a trade off. Others may have found the perfect solution..we haven't. (Yes we are investigating some of those gimbals). We found the ideal cruise speed with a 4S 5000mAh battery was about 12m/s and we are getting about 30 mins of flight time.
We have been using Agisoft Photoscan which works really well and appears to be more flexible than Pix4U. We have no surveyed ground control in the images, and we have no geotags in the photos as we were running an intervalometer script. However, it was great practice flying and processing, changing settings and trying again. You cans see that you lose images when the camera is not pointing down and loose some of the survey area. We have found that it is better to not use bad images and have gaps, rather than use them and distort the good data.
Once we had some confidence in what we were doing, we unleashed the BEAST!
First of all, the X7 is more streamlined than the X8, but doesn't have anywhere near the same room for hardware. If we were to do another flying wing, we would try the X8. We are running the X7 on Pixhawk and have a nikon J2 taking photos. The J2 is triggered from the Pixhawk via an infrared LED shutter controller.
The Nikon is snug in expanding foam with its lens fitting nicely into the camera hole in the X7. With decent batteries and a big camera, you simply can't launch the X7 by hand, so we have built our own heavy duty catapult powered by 4 spear gun rubbers;
It took a while to settle down the nav and flight constants for the X7 but it flies beautifully once tuned. It cruises at around 15m/s and is far less twitchy than the X5. Photos are higher resolution and a lot sharper. We love it as an aerial photogrammetry platform, however landing is still an issue. As well, as we are only running 4s batteries, it's always touch and go as it comes off the end of the catapult. We are still playing with battery/motor/prop combos to get the optimised take off and duration.
Again, using Agisoft Photoscan, (with Geotags, but no ground control), the results were extremely pleasing;
We are still playing and tuning, but our focus at the moment is;
1) ground control -we are looking at a network gps system where you can drop a bunch of transceivers around the survey area and have them log back to a central PC where only one of the transceivers is located in a surveyed location.
2) AUTO LANDING....WOULDN'T IT BE NICE !
3) We have purchased a 757 Ranger to try slower speeds, but significantly longer endurance to see if it improves the sharpness of the images.
Anyway, this is what we are up to. Would love to hear comments from anyone else out there chasing photogrammetry.
ausdroid : I would be happy to send you one of our frames (wings and fuse only) to play with. PM me.
Oh man, I wish I would have get this message sooner, I would have gladly listn to your offer, sadly I allready spent all my budget in the Skywalker X5 frame with its power pack, 4x 2200 4c Lipos, a pixhawk kit includding: GPS, AirSpeed sensor, MinimOSD and 3d 900mHz radio set. and a Canon Elph 130 is. I also ordered several folding props tot test them 1x 8x6, 1x 10x6 carbon fiber, 1x 9x5 carbon fiber. Also got some super thin Carbon fiber fabric to create a protection downwards (This is going to be removable and, I'm planning to make some weight tests).
Also I wanto to insert a recovery/emergency parachute system.
So as you can see, I have quite a challenge ahead, speccially considering that I'm a complete newbie in the RC world (I feel that I started in the hard way), so any advice you can give me would be much appreciated, and I would be publishing and sharing my progress here in the forum too.
Regarding the Ebee landing system, is there any way to emulate this? Can I use an infrared sensor in the Pixhawk? How about the Alt laser sensor that are getting into the market? Uf, I have so many questions...And finally, is there any place where I can find a full tutorial from 0 to 100, on how to get up and running your mapping survey UAV system, I mean, including from the building process, mission planning, to the final ortho renders? That would be awesome, because I have spent a LOT of time surfing in the Internet without getting a full comprehensive guide.
Agai guys thanks to all, really, and happy flying!
I sent you the PM but in order to proceed, the system ask me to invite you as a friend, Invitation that you must accept in order to get the PM :). It's crazy! Thanks a lot!
To answer your first question, the Ebee monitors it's approach using optical flow (basically a mouse sensor) to determine how high off the ground it is and monitors airspeed with a pitot tube. At the appropriate moment, it throws the propellor into full reverse dropping the plane to the ground. (youtube Ebee landing). So it avoids that slow roll of death by dropping quickly to the ground. Not sure about Trimble.
To answer question 2. We have now progressed a LONG LONG LONG WAY. We are building our own wings with varied profile from root to tip so that we can fly at low speeds. As well, we have mastered auto landing so that teh airspeed does not drop to stall.
I would be happy to send you one of our frames (wings and fuse only) to play with. PM me.
I was planning to setup a similar configuration with an X5, when I ran into this post, but now I'm not so sure if using this wing, or my mini Talon, any thoughs guys? Sorry for my poor English, Thanks lot!
So, according to some in this comments section, if the wings are not the most suitable solution for autolanding because of the high level of stall they have. Then I wonder how does these guys, SenseFly and Trimble did it?
In the videos you can see both drones autolanding over and over without issues right?
Zhen: yes, infrared shutter release
Hi,ausdroid,Can you share your PID parameters for x7 and x5?Thanks.
Hi,Mauricio,how do you trigger the sony nx5?By infrared?
@Hugues: not necesarily a parachute will require large landing areas. Check our video, actually the first landing on the video (in the following parachute landings the parachute was deployeed much higher on purpose) here https://www.youtube.com/watch?v=yd8JUzGGgVc
The time required for full parachute opening is very short, meaning it is deployed very rapidly so doesn`t require much altitude for a safe landing. Parachute deployment can happen in altitudes of 20m or less. With a little bit of RC experience you can land the UAV in a very small area, almost like a heli.
@Simon, I know that Tridge adjusts the altitude during his OBC (outback challenge) runs which last 30+ minutes. There is definitely a parameter that allows you to adjust the pressure in flight. I'm not sure if it can be done automatically though by attaching another baro to the ground station.
On a side note, I saw the 3DR Aero perform a 20min mapping mission in Berkley CA last week after I attended AVC & Dronecon. It was a thing of beauty watching it crab through the air (crosswind of 10m/s) during it's mission. It's autolanding landed short by about 15m perhaps because of baro drift (I'm not sure if that was the cause, it was also landing uphill which would tend to make it land short i think).