Well the gimbal controller finally showed up, it spent a week in New York, presumably making its way through customs, it was shipped from Latvia. It seems to be working pretty good, The one thing that I would definitely recommend are gimbal motors with hollow axel shafts, this would make wiring the gimbals and IMU much easier and clean. I’m now ready to mount it on the hex copter and see what happens, stay tuned…
I haven’t been doing much with my drones or my photography lately, but with more time on my hands that will soon be changing. Here is another incarnation of a DIY three axis gimbal using Turnigy 5208 BLDC motors. The rest of the parts were fabricated from $5 worth of 1.5″ x 1/8″ aluminum stock. A Basecam controller is on it’s way. Total cost of about $300, it should easily perform at least as well as one costing more than a grand, and probably more durable than a carbon fiber gimbal as well, depending, of course, on the quality of the Chinese motor bearings.
This is actually just a prototype for an ultimate build intending to cary my Nikon D800. Unfortunately my DJI “Tuned Propulsion” motor/prop combo’s don’t produce their advertised rated thrust, therefore, they can’t cary my D800. Im designing an new larger hex with higher quality motors, ESC’s, and props and it is also in the works. Stay tuned…
Since I’ve had some time in-between jobs I dusted off my franked-drone and mounted up a GoPro Hero Black and played around with it some. I didn’t spend the time to re adjust the feedback parameters for the lighter weight and it shows in the videos. The first is kind of a cool one, since I accidentally captured a deer running away.
In the second video I tried to show off and, wouldn’t you know, I flew too close to the Sun. The remarkable thing is, with this hard crash at about twenty-five MPH, my structural wood franken-drone came out unscathed with only a slightly bent landing gear. Oops, I forgot to take into account that the battery was low and therefore the copter did not gain any altitude at full throttle with full forward stick position, live and learn.
If this would have been any carbon fiber composite or aluminum metal frame it would most certainly now be worthless junk. As it stands, it bounced off the ground, I made a full recovery, and brought it safely back home in one piece. Any landing that you walk away from is a good landing!
The only damage was this bent landing gear. OK, for you engineers; How much force is required to bend a 3/8 threaded rod? This was no light crash 🙂
Since the DJI motors did not produce their rated thrust I will be building another drone, probably with T-Motors that will be sure to make rated thrust along with, most likely, seventeen inch props that will certainly be able to easily lift my D800 with plenty of reserve power.
360 degree panorama of the End of the Ash River Trail: (click on it for a larger image)
If you have been following me at all concerning my adventures into multi-rotor platforms for photography you may already know that I was pursuing a rock steady stable platform from which to take aerial photography shots from. Videography is definitely a back burner issue with me, my main interest is with still photography.
My initial disappointment was with the DJI Phantom 2 Vision in that the camera was rather poor quality, at least when measured against professional photographic equipment. The dynamic range was low, the lens was too wide an angle, the fisheye aspects were unacceptable, and worse the images from this camera were difficult at best to correct for image distortion.
I almost immediately sought out alternatives, the Go-Pro was also unacceptable to me since it also has a pronounced fisheye look to its images. Initially I adapted my Nikon J1 camera to the Phantom but found that it was simply too heavy to be safely flown with the Phantom. After exploring other avenues I found that I would have to spend over five grand to get a decent platform that could safely lift my Nikon J1, let alone my intended camera, my Nikon D800.
I was searching for a cost friendly alternative so I first built a quad using DJI’s E800 motor/ESC combination but found that these motors don’t come close to their advertised thrust in their “Tuned Propulsion System” it should, in all honesty, be called the Detuned Propulsion System. So I set out to build my hexacopter.
I was having troubles tuning the necessary vibration isolators to prevent the inevitable resolution robbing vibrations away from the camera. I was even looking to scrap my drone program entirely in favor of a balloon based system which has very little or no vibrations at all.
Then it dawned on me after a test flight. I have used tie cord as a safety backup in case the vibration isolators would become separated from the camera platform and after a previous hard landing all four indeed became detached. The next flight I forgot to reattach the isolators so the platform was hanging by the tie cord loops. The four tie cord loops were not all equal in length so the camera was flown at a ten degree, or so, tilt angle. After landing and giving my self a Homer Simpson DUH! I decided to download the flashcard and see what I got.
To my surprise the sharpest images that I have taken to this day from any aerial platform! That was the key! For the first time I was able to stitch a decent ten image panorama together! The problem with fisheye lenses is that they don’t stitch into decent quality images very well. Even though the camera was tilted and the copter wavered around due to both the normal GPS wondering and well as the ten to twenty MPH gusty breezes my stitching program, PtGui Pro, was able to easily stitch the ten images together. The other main problem with this particular panorama is that I did not take the images with enough overlap. While there are some areas of the image that certainly need improvement it is the IMAGE RESOLUTION that beats all previous images taken from any ariel platform, at least by myself!
Next to stabilize it even more I will be looking into a downward facing stabilization camera to supplement the GPS for position hold as well as an ultrasonic range finder to supplement the altitude hold function. Using vibration isolators between the camera platform and then suspending the gimbal from the airframe with tie cord is a perfect answer for total vibration isolation for still imagery, while this is obviously not a very good solution for videography – well I really don’t care that much about moving pictures anyway 😉
Update: I may have spoken too soon when suggesting that tie cord may not work for video, here is a video taken with the exact same setup as was used for my stitched pano:
You can clearly see the difficulties in taking a series of still images to stitch together for a pano, the copter is flailing around in the wind. Most of the jitteriness seen in the above video would be minimized when a two axis stabilizing gimbal is utilized. Note that the video from the Nikon J1 is not very good to begin with, compared to the D800, slow panning on a stationary tripod results in marked loss of resolution, not seen at all in this video. I am becoming convinced that a third axis gimbal motor may be necessary due to the unreliably unstable rotation control of the hexacopter is around the z-axis, especially when windy. Yup, retractable landing gear and a third axis gimbal motor may ultimately be necessary.
Well here it is, my first incarnation prototype for a HexCopter. I have to say that a hex handles so much nicer than a quad, much more stable and predictable. This version weighs about 11 lb. (5 kg) or about 830 g/motor or just 30 g above DJI’s recommended 800 g/motor. The total maximum flight time, with an 10,000 mAh battery, was just under 20 min. with the final battery voltage of 21.35 Volts. The DJI ESC’s started giving yellow LED signals with a rapid loss of altitude afterwords. Using a Return To Launch (RTL) voltage of 22.2V should give ample reserve RTL time for a useful flight time of about fifteen minutes. Update: My battery charger reported that it took 10,325 mAh to recharge the battery.
There are several areas where weight can be shaved to allow for the additional weight for my Nikon D800. I am still fine tuning the vibration isolators for my Nikon J1 camera, there is no gimbal motors used at this time. If you look closely at the video the Nikon J1 is having severe problems with the autofocus, I’m probably going to have to give up and simply set the focus manually to infinity, as well as resort to using manual or aperture exposure modes, and forget about 360 degree pano shots, especially near sunrise or sunsets.
I’m not yet sure if I need to reduce the number of isolators, I’m currently using six DJI phantom isolators. I bought isolators for DJI larger gimbals but I found that these were way too stiff for the Nikon J1, although those are probably the ones I will need to use for my D800.
For all of those paranoid morons who are chomping at the bit to shoot down a drone I added an example of just how close a typical drone used by an amateur photographer would have to be to get any meaningful images. All of you dipsticks should realize that only a multi-million dollar military grade drone will be able to count the pimples on your nude sunbathing girlfriend/wives butt-cheeks, and from an altitude higher than you will ever be able to see or hear it from, let alone, shoot it down from 😉