Posted by SkyrisFX on November 18, 2013 at 10:04am
Hey everyone! In case you haven't been following us on our website or here on DIY Drones, we are two guys who have been tinkering with gimbal design and other aerial photography related projects. Over the last few months we've been developing a brushless gimbal and we're almost ready to make it a deliverable item. We have aspirations to turn our tinkering habit into a business, but we're quite new to the scene, and we are experimenting in that regard. Special thanks go out to all of you who have encouraged us with comments and emails! We appreciate it!
Today we would like to introduce you to our first official product, our 9 Inch High Rise Multicopter Legs. By selling these legs we hope to...
Develop our order fulfillment and customer service process with a simpler product.
Raise some funding to support our current and future projects.
The kit contains 4 Garolite leg parts which make one pair of legs. The legs have been pre-drilled to work with 3DR ArduCopter arms but they can be easily modified to work with other kits. All required hardware and fasteners are included.
We are listing the legs at $17.50 which is currently cheaper than 3DR's "long leg set." These legs are also around 3 inches longer than those available from 3DR.
We've been using these legs for our project for months now and we're happy to tell you that they are quite strong. They've survived many hard landings (some while carrying payloads up to two pounds) and if they can survive our terrible piloting they can survive a lot! They are available for purchase now on our products page.
In other news, as we mentioned above we are nearing the final stages of our gimbal development project. We've recently tested it and the resulting footage was excellent (videos coming soon). We just need to make a few more modifications before we can begin pre-orders.
We also have a new and exciting project in the works! More info on that coming soon.
If you have any questions feel free to leave a comment or you can email us at skyrisfx@skyrisfx.com. Many thanks to the community for providing encouragement and useful knowledge. Cheers!
Hey DIY Community! It's been a while since we've posted on the site and we wanted to share some of the progress we've made on our gimbal design project. If you're interested in our project please visit our blog. It's filled with a lot of great photos and videos. We also try to add useful information from time to time - we have a very detailed post about PID tuning brushless gimbals.
Below I've added some renders of our latest gimbal prototype. We'll be receiving the parts from the machine shop in about a week. Once we do, we'll be testing and documenting the build on our website. For now I hope you enjoy these previsualizations.
The Skyris Mark VI gimbal is designed to reside at the front of the multicopter allowing for a clear camera view with no arms or legs in the shot. The gimbal secures to the copter via two arm clamps. The central widget allows the clamps to telescope outward so they can accommodate different multicopter frames.
Here the gimbal is configured for compatibility with copters that have a wide arm configuration. The Skyris Mark VI Gimbal Prototype can adjust to fit copters that have a 7" to 12" gap between arms.
Each clamp has the ability to swivel and fit different arm widths. Rubber grommets placed on the inside of the clamps mute vibration and add friction. Once the clamps are tightened the gimbal will lock firmly in place (no drilling required) on the arms of the copter.
An optional battery holder can be affixed to the rear arms of the multicopter. Placing the battery on the rear of the copter will help offset the weight of the gimbal and reduce the need to re-tune copter PIDs.
Older Designs...
As I mentioned before, it's been a while since we've posted on DIY Drones and our gimbal has evolved through many form factors in the interim (all of which are documented on our blog). We've had a blast trying out some very unique designs.
This version featured a central pitch/roll axis which was affixed to the center of the copter. The Gopro sits at the front of the copter so the arms and legs are out of shot.
The flight results were quite good, but we decided that the unit was too heavy - it's defeating to add so much weight to stabilize a camera that's a favorite because it's very light.
Many of our recent prototypes are cut from G10 Garolite material, which is roughly half the weight of aluminum and comparable to carbon fiber in strength. Our thanks go out to Jordi Orlando of DIY Drones for the suggestion.
If you peruse our website you might find yourself chuckling at some of our older and admittedly wackier concepts. This project has definitely been a learning experience for us and we've had a great time so far. We hope to share more with you soon! Thanks!
Thanks to everyone for your awesome input on our first post! Several of the tips we received have had a strong influence on our development path. We are already working on a radical redesign for our Mark III prototype that will incorporate some of your suggestions.
Where we left off:
Our last prototype had some semi-successful results. Mark I, which we now refer to as the “Tank” was much too heavy. After stripping it down we were able to get it into the air and shoot some decent footage. However, flight control was sluggish and somewhat unpredictable.
So we designed Mark II “Skeleton”
Pictured above you can see Mark I “Tank” and Mark II “Skeleton” side by side
For this version we made several major changes to the design:
Used a skeletal approach to the frame design
Removed as much metal as possible
Shortened the entire frame by 3 inches
Used 1/16” metal instead of ⅛”
Added multiple weight compartments
Simplified gimbal mounting
Spread out the placement of vibration mounts
Reduced number of plates
Moved battery onto the gimbal
Before we designed our new “skeleton” frame, we performed some rigidity testing on 1/16” aluminum. We found that as long as we kept support spacers within 3.5 inches of each other, 1/16” aluminum would be rigid enough to support the gimbal.
We also did some testing to determine optimum GoPro placement. We found that in order to maintain a clear field of view with the widest angle video setting, the GoPro could safely be placed nine inches from the center of the copter. This allowed us to shorten the entire frame by three inches.
We also refined our gimbal balancing approach. In Mark I “Tank” we tried to selectively cut out metal to balance the gimbal. Ultimately we had to add a stack of washers onto the back in order to balance everything out. We felt that this was not an elegant approach and the washer stack was rather ugly. So we removed the extra metal, and then designed several compartments for washers. This gave us more flexibility in balancing the gimbal while maintaining our design aesthetic.
On Mark I “Tank” we placed our vibration mounts close together. This created an unintentional joint and the gimbal had a fair amount of play which caused a swaying motion in flight. In response to this problem, we decided to spread out the vibration mounts. This greatly simplified the way our gimbal attached to the Hexa frame by allowing us to remove several heavy aluminum plates.
As many of you pointed out, moving the battery onto the gimbal is a much more efficient use of weight for balance. Coincidentally our 7 ounce battery approaches the weight needed to balance the GoPro carriage on the opposite end of the gimbal. This also allows us to keep more weight below the vibration mounts while lightening the overall payload of the Hexa.
With all of these changes designed into Mark II “Skeleton”, we sent it off to be cut out of 1/16” aluminum!
Our machinist was gracious enough to send us some pictures of the CNC Router used to cut our gimbal parts. In the image below you can see the cut marks from our plates in the backboard. There are some more pictures and info about CNC Routers on our blog here.
The Results:
Mark II “Skeleton” is 40% lighter than Mark I “Tank”! Including the battery, our new payload weight is 36.25 ounces (2.66 lbs.) down from the previous payload weight of 56.75 ounces (3.55 lbs.)
When we took to the air it was immediately apparent that the Hexa could easily handle the new payload weight and maneuver smoothly.
How was the flight and footage? Check out this video and see for yourself.Please Note: This video showcases clips from the GoPro that are unprocessed, as well as clips that have been processed. The processed and unprocessed clips are indicated by text in the upper right corner.
As you can see, we were able to fly for a reasonable amount of time with this payload weight. We were airborne for around 6 minutes and still had some charge left on the battery.
The level of vibration in the footage was encouraging. We put 2 clips through the Adobe After Effects Warp Stabilizer filter in an effort to easily identify the “jello” distortion in our footage. We were pleased to see that there was little to no distortion present. We appear to be isolating the GoPro from the high speed micro-vibrations generated from the spinning motors.
Our footage is still suffering from some macro-vibrations. We believe there are two main issues. First we need to balance the props and design some new mounts that will dampen the motors vibrations directly. We have noticed some warbles in flight even when the gimbal is not attached.
Second, we need to look into fine tuning the servo response time. We’ve noticed a rocking action in the video when the Hexa quickly accelerates from side to side. It appears to be a result of servo latency.
What we’ve learned from this prototype:
It flies!
Acceptable level of controllability
Reasonable amount of flight time, 6+ minutes
Decent raw footage
Little to no “jello” from micro-vibrations
Issues with macro-vibrations
Roll servo response time issues
Could be even lighter
Where are we now?
True to form we are ready to confront our next challenges. We are already designing our Mark III prototype. For this next iteration we are considering a radical redesign:
Moving the pitch axis to the center of the gimbal
Dropping the “H” frame for more of a single “I” beam approach
Getting rid of all the ServoCity parts
Isolating the motor mounts
Researching composite materials other than aluminum
Building a neutral density filter mount for the GoPro
Stabilization:
On our first post, several commenters suggested moving the pitch rotational axis from the GoPro Carriage to the center of the gimbal. We have been looking into this option and believe that it may help us in several ways.
Firstly we can get rid of a lot of the hardware needed to rotate the GoPro carriage. Secondly it will allow us to drop the “H” frame and go for a much simpler “I” beam shape. Thirdly, as several commenters pointed out, this puts our axis on the balance point, which means gravity will contribute towards keeping the gimbal level.
Further Weight Reduction:
While we’ve been very happy with the ServoCity parts, they do add a significant amount of weight. Our new goal is to design a direct drive system that is strong enough to support the chassis so we can disregard the heavy aluminum servo blocks.
Vibration:
We’ve also learned that isolating the gimbal alone will not solve all of our problems. This is why we’ve decided to design some anti vibration motor mounts in an effort to attack the problem at its root. Hopefully our mounts will provide the solid, rigid mounting needed for the motors while providing some vibration isolation for the Hexa frame.
Materials:
We are in the process of investigating some of the materials that were suggested to us by the commentators of our first post. We are very interested in Garolite G10 as it looks to have the strength-to-weight characteristics we are looking for without the high price of carbon fiber. However, it’s more practical for us to continue building our prototypes with Aluminum for now. Once we are satisfied with the functionality of our design we may experiment with Garolite.
Reduce Video Distortion and Improve Picture Quality:
We are also considering the addition of a neutral density filter for our GoPro. As we have been researching the reduction of video distortion in GoPro footage, we have come across several references to that fact that the “jello” effect is less severe on cloudy or darker days. This is something we have seen in our own footage as well.
If you are interested, have a look at our blog post:Neutral Density For The GoProin which we go into more detail about our hypothesis and how ambient light levels augment rolling shutter distortion. We’ve summed up our theory below. Unfortunately we’ve been unable to find any concrete information on the subject. If anyone can provide some additional input we will be greatfull!
Our Theory:
The GoPro uses a CMOS sensor which scans through the entire frame at a fixed rate. This means there is a fixed amount of time required to read the entire sensor. On a very bright day this could lead to a significant time gap between pixel sampling as the exposure time in that situation is very short. This would also lead to a very sharp exposure for each pixel. However, on a darker day the exposure is longer and each pixel is sampled for a longer period of time. This would increase the motion blur of the pixels and a reduction of time difference between pixel sampling. Both of those factors could cause the captured image to be more blended between pixels thus reducing the amount of “jello” distortion visible...
... One way to force the GoPro to use a longer exposure time on a bright day is to basically put sunglasses on it. A neutral density filter is a material that will reduce the amount of light that enters the lens without distorting the color of the image.
In an effort to test our theory, our next prototype will include the ability to insert neutral density filters of different F-stop levels onto the GoPro carriage.
Here is the part where we need your help!
We would very much appreciate any input and or experiences you can share with us regarding the following items:
Motor isolation/dampening, what has worked for you? Problems? Limitations?
The use of neutral density filters with a GoPro, has anyone tried it? How did it work for you?
Do you know of any supply sources for composite material, especially Garolite G10? Where have you ordered from and what was the experience like?
Though we are very encouraged by the latest results of our test flight, our work on Mark II “Skeleton” has taught us a lot and we still need to refine and improve our design. We are now turning our efforts onto Mark III and look forward to sharing our progress with you soon.
We will continue to post our major milestones here on DIY Drones. If you are so inclined, you can also keep up-to-date on our incremental progress via our blog:http://www.skyrisfx.com/mission-updates/
Hey everyone! This is our first post to DIY Drones, though we've been following this community for some time and have found the depth of knowledge here amazing! For the past few months we've been working on a unique GoPro gimbal design for the 3DR Hexa. We are now at a point at which we feel like we've made enough progress to share some of the results with this community and hopefully get some feedback.
About Us:
We are two guys, Jeff and David, with active careers in the broadcast industry. In addition to being enthusiasts of the UAV hobby, we see enormous potential for cost effective video production solutions. With news that the FAA will soon legislate commercial use, we've started investigating potential video production applications with our 3DR hexacopter. Read more about us here...
As many of you have experienced, we quickly ran headlong into the problem of vibration induced video distortion (better known as jello)! We tried several inexpensive gimbals on the market without much success. Obtaining a camera view that was unobstructed by the copter frame was also problematic.
So we decided to go DIY!
Gimbal Requirements:
Once we decided to design our own gimbal, we set down the main requirements that our prototype should meet.
Vibration isolation: Since our primary application will be production quality video, our main objective is to eliminate as much vibration related video distortion as possible. The video should not require post-processing to remove distortion.
An unobstructed view: The camera’s field of view needs to be completely unobstructed by the helicopter frame. No paying client will tolerate a landing gear or props in the shot, distracting from his or her product.
Plug and Play: Our gimbal system should directly attach to the 3DR frame without the need for additional drilling or modifications.
No Tuning: The gimbal should be balanced and centered relative to the 3DR Hexa frame, resulting in smooth flight without PID adjustments.
Affordable: Through the use of select materials and efficient design, we hope to achieve a reasonable production cost relative to the cost of the 3DR Hexa Kit.
Aesthetic Design: The gimbal needs to be well designed and professional looking. Something that looks cobbled together will not inspire client confidence in the quality of the final product.
The Story So Far...
With these requirements in mind, we set out upon the rocky road of development!
As any good project should, we started with a discovery and research phase where we investigated many different options and approaches. As mentioned above, we started by looking at basic gimbals that were already available. In all cases, we found that in order to achieve an unobstructed view, the gimbal needed to be mounted out on the arms of the hexacopter. Doing so would imbalance the copter, requiring it to be tuned at the software level. This placement also introduced more vibration into the gimbal.
We decided to tackle the vibration issue first, and then design a form that would meet our requirements. As we began researching ways to dampen vibration, we discovered that the three main factors involved are:
1) the weight of the supported object
2) the disturbing frequency (RPM)
3) rigidity of the structure isolated
We started out under the assumption that our gimbal would need to be heavy enough to create a static load within the deflection material, but not so heavy that it would overstress the material. So far we've found that it’s been difficult to find a sweet spot - one that is heavy enough to provide enough compression on the isolator, but not too heavy for the copter to lift.
At higher disturbing frequencies the required minimal thickness of the isolator can be reduced. Because the helicopter operates at variable disturbing frequencies, we determined that the thickness of our isolation material should be based upon the lowest disturbance RPM. Since our motors have a KV of 850 and operate at a maximum of 12 volts, the maximum RPM should be less than 10,200. Since hovering is usually achieved under 50% throttle, the low side of motor rotation for flight should be above 4000 revolutions per minute. For this reason we chose isolators with 5/16” thickness. This should provide us with isolation efficiency of 95% or better. More on the science of vibration reduction here: http://www.easyflex.in/pdff/latest/Vibration%20Isolation%20Theory.pdf
Once we had the vibration mounts, our goals, and the dimensions of the GoPro camera, we were ready to design our gimbal frame. We decided to go with an “H” frame that would be attached to the copters center and yet hold the GoPro carriage far enough in front of the copter to obtain an unobstructed view. Given the APMs native support of servos, we decided to steer away from brushless motors for now. We placed the roll servo in the center, and the pitch servo with additional ballast weight in the back to balance everything out.
Now that we had a form in mind, we needed to work out how to mount everything together. It quickly became apparent that the gimbal carriage would need to be firmly mounted, so that it did not add vibration, while being able to spin smoothly. The meant we would need ball bearing mountings. While looking for an affordable solution, Jeff came across ServoCity.com and found exactly what we were looking for.
Once the parts arrived in the mail, we bought some ⅛” X 1” aluminium strips and started cutting and drilling in our garages. We built the entire “H” frame and assembled all of the components. The gimbal had a very smooth movement on both the roll and pitch axis. The frame was rigid and solid, and protected the GoPro very well. It gave a clear and unobstructed view from the hexacopter
It just had one major problem, it was way too heavy! This gimbal rig was approaching 4.5 pounds and there was no way the hexacopter was going to be able to get off the ground, much less fly in the controlled and stable manner needed for video production.
We decided that we needed to reduce the weight as much as possible and this was going to require a high tech solution. David devised a calculator to help us determine optimal hole placement within the frame. Once we were comfortable with our layout we sent the design off for CNC routing.
How did it all work out? Check out the video and see for yourself. Please Note: there has been no post processing of the resulting GoPro video.
As you can see our first prototype is still too heavy. The good news is that our vibration isolation method seems to be effective based upon the limited amount of video we captured. That said, there is still work to be done! We've revised the design yet again, and our Mark II version parts should be arriving in the mail shortly.
Changes to the design include a much lighter chassis built from a thinner aluminum. After a few rigidity tests we believe we can reduce weight by using a 1/16” plate. We’ll also be removing as much metal as possible. The end result should look something like a skeleton relative to our current prototype. Another change will be the incorporation of the ability to modify the weight and thus the balance of the gimbal chassis. This will allow the gimbal to work with multiple GoPro versions and accessories. We will do this by adding several weighting compartments on the chassis. We are also planning on relocating the main battery to the rear of the gimbal to contribute to the weight needed for balance. This will further reduce the overall gimbal weight.
Here is the part where we need your help!
Since we only have one hexacopter for testing purposes, any recommendations regarding payload limitations would be appreciated.
We are interested in how much weight you have been able to successfully fly with?
What was the effect upon flight time?
Which frame were you using?
What motors, props, batteries, ESCs, etc. were used?
We are also interested in any additional methods you may have used for vibration isolation.
What was effective and what wasn't?
We are very determined and optimistic that we can successfully create a working system with these goals in mind (though we might have a few productive failures along the way). If you’re interested in reading more about our journey, we will be posting regularly on DIY drones and you can also follow our progress on our blog here:
