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Old Nov 07, 2012, 04:36 PM
Registered User
Chile, Santiago Metropolitan Region, Stgo
Joined Mar 2012
34 Posts
Mini-HowTo
Cheap tricopter for amateur videos

Just thought I'd share my tricopter and camera anti-vibration system!

Scratch built cheap wooden tricopter for amateur aerial videos:
Frame based on RCExplorer 2.5 with 1/2 inch arms, hallstudio's cheap and easy yaw mechanism - but not crooked .

I designed the camera anti-vibration system which can be easily tunned to dampen different frequencies and for different cameras weights by adjusting the foam compression.

It works better than I expected. I began with low compression and just started compressing (using the screws) until I had NO JELLO! YAY!

Self level with firmware v1.4 seems to work great (tested at the end of the video)

Now I just have to learn to fly this thing

Other details:
GoPro Hero 2 @720/60fps
FC - KK2 with 1.4 firmware (still stock settings, I haven't adjusted P&I)
NTM 2836 750kv motors
11x4.7 props
Turnigy Plush 30A ESCs
Turnigy 2216mg servo
Landing gear that has resisted a lot of crashes - 1/2 inch sections of a 6 inch PVC tube

Video:

El Cheapo AP tricopter KK2 v1.4 (4 min 41 sec)


Update 1: I've uploaded another video showing the results of four different compressions settings. See post #3

Update 2: Another video flying with broken prop, bent and loose motor mount vibrating badly and still no jello in video. See post #12

Update 3: Added a few videos and photos of tests with a different camera, Sony RX100. See post #25
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Last edited by stevenharting; Nov 19, 2012 at 04:13 PM. Reason: added info
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Old Nov 07, 2012, 10:36 PM
Registered User
Joined Aug 2012
100 Posts
Now that is a cool dampening system! Thanks for the informative post, just a question though.

Your landing gear is very small. If you made it larger (more height from the ground to your motors) I think it would make landing easier and you wouldn't worry about the props hitting the ground at a slight angle
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Old Nov 08, 2012, 08:43 AM
Registered User
Chile, Santiago Metropolitan Region, Stgo
Joined Mar 2012
34 Posts
Tests and details

Yes, I tried bigger 8 inch PVC tube for the landing gear buy I think its too bulky and makes the tri too easy to be pushed around by wind.

I'm really happy with the way camera dampening system is working. The attached pictures show more detail. The idea is that the dampening system (shown in green) sandwhiches the frame (shown in blue) between the two sets of foam so there is no rigid connection that can transfer vibrations between it and the frame. No solid part of the dampening system touches the frame, only the foam so the stiffness can be adjusted by compressing more or less with its screws.

The battery is attached to the bottom plate of the dampening system which gives it more mass, also reducing vibrations.

The FC board is mounted directly on the frame. I'm not sure if its better to mount it on the dampening system, but I've had no problems with it this way.

I've uploaded another video showing the results of four different compressions settings.

Tricopter camera dampening tests (3 min 1 sec)
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Last edited by stevenharting; Nov 08, 2012 at 08:45 AM. Reason: Added info
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Old Nov 08, 2012, 09:51 AM
Registered User
United States, FL, Bradenton
Joined Jan 2012
301 Posts
Just wondering if using a few different types of foams with varying densities glued together like a sandwich would help to isolate the vibrations better than a singe piece?
Possibly with a higher density nearer to the frame to knock down the heavy noise and graduating to a softer material to get the last bit out?

Also do you think that lengthening or shortening the booms to tune out vibration is possible to get the harmonics minimized?
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Old Nov 08, 2012, 10:32 AM
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Chile, Santiago Metropolitan Region, Stgo
Joined Mar 2012
34 Posts
Yes, different foam densities sandwiched should definitely help absorb different frequencies (and amplitudes). That is what I was going to test next... but I'm so happy with the results I got that I'm not sure if I'll do it right away. This is with the GoPro Hero2.

I may have to test this when I use other cameras since I hate the fish-eye lens in the GoPro. I have a sony RX-100 that I will try, but this camera has a pretty good optic stabilisation so I don't know if its necessary...

Regarding arm length to tune out harmonics, that is definitely an option since the arm length defines its resonating frequency (together with its shape and material characteristics). At least thats what I was thought in engineering class... if I remember correctly

I have tried lengths from 10" to 20" but in different tricopter builds so its hard to compare since there were a lot of other differences between them. The only obvious difference I noticed was flight characteristics, acrobatic/nimble vs slow and stable...
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Old Nov 08, 2012, 10:49 AM
Stop me before I build again!
United States, NY, Albany
Joined Sep 2012
1,320 Posts
Quote:
Originally Posted by stevenharting View Post
I have a sony RX-100 that I will try, but this camera has a pretty good optic stabilisation so I don't know if its necessary...
Camera stability functions are design for hand shake and can often make the images worse for the AP use case. On top of that not every camera stability system can be turned off ( and locked ) fully for AP use.
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Old Nov 08, 2012, 01:14 PM
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United States, SC, Irmo
Joined Mar 2012
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I was wondering if there is a size that arms need to be. Meaning the 2 front arms versus the rear arm. Should they be the same size? Length. I just ordered the parts to try my first scratch build. Thanks for the help.

Tom
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Old Nov 08, 2012, 02:03 PM
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Chile, Santiago Metropolitan Region, Stgo
Joined Mar 2012
34 Posts
Most people use the same size for all arms, though its is not necessary. I built a tricopter with the rear arm longer than the other (and I have seen others do it too) and it flew fine. The idea of having different lengths (in theory) would be that, for example, if the rear is longer the tri would be slower or more stable in changing pitch angle.

I'd say you can use different lengths if you are looking for some specific flight characteristic. If not, then make them all the same this way its easier to make spares. "One size fits all"

One thing you have to keep in mind when doing different lengths is Flight Controler position. This also depends on the Flight Controler. For example original KK boards only have gyros, no accelerometers, so they can be place pretty much anywhere. FCs with accelerometers on the other hand must be placed on the CG.

This is because accelerometers measure movement (or change in speed) in XYZ. Gyros on the other hand only measure change in angle (attitude).

To illustrate:
When you pitch forward, what should happen ideally is that the tail goes up and the front goes down, keeping the CG at the same hight. If you place the board way back of the CG and you pitch forward the board will tend to go up with the the tail.

If the FC has only gyros it won't care its going up, it will only care it is leaning forward.

If the FC has accelerometers (and is using them i.e. with self level on) the board will think the whole tri is going up and will adjust accordingly, making the tri dip in height when pitching forward. It will try to make the board keep its hight, not the whole tri (or its CG). This effect will probably not make the tri unflyable, but it will certainly cause strange flight characteristics making it difficult to trim
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Old Nov 08, 2012, 03:11 PM
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United States, SC, Irmo
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Thank you for the response. So it would be best if I placed the board at CG no matter which board I use and arms of equal length. I have ordered the KK compatible board and USBasp programmer from Value in tri-copter configureation and also two KK2 boards from HK. They both look to be fairly easy to use for the new guys like me. I suck when it comes to computers. I do want to try and learn though. Again I thank you.

Tom
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Old Nov 08, 2012, 03:30 PM
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Chile, Santiago Metropolitan Region, Stgo
Joined Mar 2012
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You are most welcome! I know these things can be confusing or at least I certainly know I was confused for a long time when I started

You should checkout David Windestal's tutorials I you haven't done so.

He has made a lot of tutorials including firmware flashing on KK boards:
http://rcexplorer.se/educational/201...king-kk-board/

Don't get intimidated by the first part of the tutorial (the part about making an adapter for the USBasp programmer) since the programmer from Value already comes with the 6 pin adapter to connect it to KK boards.

His other tutorials are also worth the while because he goes step by step and in general does a good job explaining the reasons for his choices.

Also keep in mind that the KK2 boards do have accelerometers, though they are only used when self-level is turned ON

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Last edited by stevenharting; Nov 08, 2012 at 03:31 PM. Reason: typos
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Old Nov 08, 2012, 04:46 PM
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United States, SC, Irmo
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Just went to check out the web site. I like the title exploring RC one crash at a time. Thats me. Thanks. I'm sure I'll spend quite some time reading. I think it will be even better when my flight boards arrive. Do more of a hands on thing. Thanks again.

Tom
Update: I've been reading about the Value Hobby KK board I ordered, it says blue version whatever that means. Its looking like it might be fairly simple to use. The board and all the tri copter parts should be here tomorrow. Well back to reading the manual and the one crash at a time web site. Love that name.
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Last edited by carr52; Nov 08, 2012 at 05:19 PM.
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Old Nov 09, 2012, 08:28 AM
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Chile, Santiago Metropolitan Region, Stgo
Joined Mar 2012
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Another test of the camera dampening system.

Late afternoon with a lot of wind but decided to fly anyway because I had already charged a few pack earlier and did not want to discharge with charger because it take too long.

Caught a strong gust of wind, got scared I would crash into electricity cables, lost control and crashed into the ground. This is nothing new, I'm a newb at flying this thing

Broke a prop, bent a motor mount but just took off immediately to test the camera dampening system.

Even with a broken prop and a bent and loose motor mount vibrating badly the dampening system worked great!!

NO JELLO!!!

Gopro Hero 2 1080p@60fps FOV medium

Video:
Cheapo AP Tricopter - Cam dampening system test 5 (2 min 13 sec)
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Last edited by stevenharting; Nov 09, 2012 at 08:32 AM. Reason: forgot to add video link
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Old Nov 09, 2012, 09:01 AM
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A question I've been meaning to ask is what setting do I use on my DX6i. acro or heli? The parts for my tricopter arrived. According to the tracking info. I'll go in and check the mail later this morning. Too cold right now and I need more coffee first.

Tom
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Old Nov 09, 2012, 10:42 AM
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Chile, Santiago Metropolitan Region, Stgo
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Quote:
Originally Posted by carr52 View Post
A question I've been meaning to ask is what setting do I use on my DX6i. acro or heli? The parts for my tricopter arrived. According to the tracking info. I'll go in and check the mail later this morning. Too cold right now and I need more coffee first.

Tom
I'm not really sure. I have read that it depends on the flight controller you use. For KK boards i think you should use acro (its easier, no messing around with mixes etc...). I have only used acro (hitec and turnigy radios, KK, KK2 and multiwii FCs)

But I have read that for other FCs like Naza you should use heli mode with the DX6i:

http://www.multirotorforums.com/arch...p/t-2413.html?
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Old Nov 09, 2012, 12:13 PM
<Marty>
United States, KY, Springfield
Joined Jul 2011
1,818 Posts
do not use Heli mode ! it mixes the channels for collective pitch on heli's and will make your tricopter not flyable and most defiantly will result in a crash...
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