The simple fix for vibrations, more mass?

So I forget exactly who said it, but in one of the many vibration threads someone made a note about how "maybe a little more mass helped stable out the APM".  Now I know there are some neat rigs out there but I want things simple, so for a simple test, I took the heaviest small item I had lying around, a ~90gram foil pommel, and just taped it to my APM.

The results were good.  I think a properly sized and fitted plate, maybe on the bottom, would help a lot.  Again, I just stuck the weight on there, in the only way it could fit, this was a crude test, but I think it has merit.

(The APM is has two pieces of moon gel between it and the frame and it's secured with a piece of velrco.)

Before: I was +/- 5-6 with a greater min/max change. 

3691008068?profile=original

After I was +/- 3-4 and much smoother.

3691008036?profile=original

ENGINEERING!

3691007996?profile=original

You need to be a member of diydrones to add comments!

Join diydrones

Email me when people reply –

Replies

  • Credit to  R_Lefebvre for a great idea!

    Let me clarify, I have two pieces of moon gel on the bottom secured by a piece of velcro.  Also, I follow 100% what you're saying about helicopters.  Oddly enough, I've had less trouble getting my helicopter happy in terms of vibration compared to my quad.

    Richard,

    I don't think everyone will have the same amount.  I added a lot and crudely for this test, but I think better placed mass will do much better.  I think this a good example of keep adding or taking away until you get things right.  I also have more wires that I'm just not going to bother dampening because I just don't care, and I also don't have OCD over balancing props, so I'll probably end up more mass than the normal person.  I like modular systems that can be quickly changed or moved around and there is performance cost for that.

  • That was me.  Yes it works.  Though... not quite what you've done.

    What have you done?  Is there any damping in the system?  I just see a lump of metal stuck on the APM?

    For my 550 heli that I'm working on, I have a 3" x 3" x 1/8" square of Aluminum, suspended on rubber bulb dampers in the corners.  The APM is rigidly bolted to that.  I think it should work well.  Hopefully test soon, maybe tomorrow.

    You do have to watch out with these systems, that you don't drive the natural frequency of the mass too close to the control frequency, or primary vibration frequency of the Copter.  This is less of a problem for multi-rotors.  The control frequency tends to be low, and the vibration frequency is high.  So there's lots of room between the two.  However, a Tradheli, the control frequency and vibration (or rather, shaking frequency) of the heli are closer together, so it's hard to come in right at the right spot.  Suffice it to say, if you can see the thing shaking, it ain't gonna work.

    And again, you want the mass spread out in a flat plane, and the dampers have to be wide-set.  Think of a racecar hugging the road.  What you have there, is a lot like this.  And this didn't work well at all.  This was the "Roly-Poly".

    DSC00236.jpg

  • T3
    Now the question is how little weight can we add and still get good results? Since weight is our enemy with regards to flight time.

    I also notice that when I doubled my battery from 4S 5000mAh to 2-4S 5000mAh, that my zAccel went bad and alt hold failed. The copter flew, but alt hold was all messed up. Went from 16:30 to 21:30 in flight time. Either something is out of balance or I'm getting some kind of harmonic at the faster spins on the motors to maintain altitude.
This reply was deleted.

Activity

DIY Robocars via Twitter
How to use the new @donkey_car graphical UI to edit driving data for better training https://www.youtube.com/watch?v=J5-zHNeNebQ
yesterday
DIY Robocars via Twitter
RT @SmallpixelCar: Wrote a program to find the light positions at @circuitlaunch. Here is the hypothesis of the light locations updating ba…
Saturday
DIY Robocars via Twitter
RT @SmallpixelCar: Broke my @HokuyoUsa Lidar today. Luckily the non-cone localization, based on @a1k0n LightSLAM idea, works. It will help…
Thursday
DIY Robocars via Twitter
@gclue_akira CC @NVIDIAEmbedded
Nov 23
DIY Robocars via Twitter
RT @luxonis: OAK-D PoE Autonomous Vehicle (Courtesy of zonyl in our Discord: https://discord.gg/EPsZHkg9Nx) https://t.co/PNDewvJdrb
Nov 23
DIY Robocars via Twitter
RT @f1tenth: It is getting dark and rainy on the F1TENTH racetrack in the @LGSVLSimulator. Testing out the new flood lights for the racetra…
Nov 23
DIY Robocars via Twitter
RT @JoeSpeeds: Live Now! Alex of @IndyAChallenge winning @TU_Muenchen team talking about their racing strategy and open source @OpenRobotic…
Nov 20
DIY Robocars via Twitter
RT @DAVGtech: Live NOW! Alexander Wischnewski of Indy Autonomous Challenge winning TUM team talking racing @diyrobocars @Heavy02011 @Ottawa…
Nov 20
DIY Robocars via Twitter
Incredible training performance with Donkeycar https://www.youtube.com/watch?v=9yy7ASttw04
Nov 9
DIY Robocars via Twitter
RT @JoeSpeeds: Sat Nov 6 Virtual DonkeyCar (and other cars, too) Race. So bring any car? @diyrobocars @IndyAChallenge https://t.co/nZQTff5…
Oct 31
DIY Robocars via Twitter
RT @JoeSpeeds: @chr1sa awesomely scary to see in person as our $1M robot almost clipped the walls as it spun at 140mph. But it was also awe…
Oct 29
DIY Robocars via Twitter
RT @chr1sa: Hey, @a1k0n's amazing "localize by the ceiling lights" @diyrobocars made @hackaday! It's consistently been the fastest in our…
Oct 25
DIY Robocars via Twitter
RT @IMS: It’s only fitting that @BostonDynamics Spot is waving the green flag for today’s @IndyAChallenge! Watch LIVE 👉 https://t.co/NtKnO…
Oct 23
DIY Robocars via Twitter
RT @IndyAChallenge: Congratulations to @TU_Muenchen the winners of the historic @IndyAChallenge and $1M. The first autonomous racecar comp…
Oct 23
DIY Robocars via Twitter
RT @JoeSpeeds: 🏎@TU_Muenchen #ROS 2 @EclipseCyclone #DDS #Zenoh 137mph. Saturday 10am EDT @IndyAChallenge @Twitch http://indyautonomouschallenge.com/stream
Oct 23
DIY Robocars via Twitter
RT @DAVGtech: Another incident: https://t.co/G1pTxQug6B
Oct 23
More…