Vibration is the bane of multirotors, and needed something that I could produce very inexpensively in small quantities for quadcopter builds and other robotic applications. This is what I came up with that I could cut on demand on the waterjet.
I have used zip ties, nylon screws and traditional bolts with nylock nuts to secure them in a frame, and were very impressed with the operation, if you want a set to try please let me know and I will cut a few on the next production run.
Comments
You are right Eric my exploration in mitigating vibration is two fold however there is a bit of science behind the blocks, while also incorporating some fundamental design that on impact it provides a method of breakaway. The curve cut is designed in and attempt to have counter resignation, I borrowed this from late 1980s early 1990s spline skiing technology. Not sure how well it is going to work in the real world yet however I will have several mounts built up this week and hope to get lots of flights with the ability to compare the results to the controlls and see how effective they are in arresting the particular vibration frequency to which I am trying to mitigate.
The other goal was to make these really cheep, as my price point for the mounts and blocks is targeted as sub $2 each
Not sure I agree that "vibration is the bane of multirotors."
However I would agree that vibration is the most popular irrational fear among superstitious multirotor enthusiasts, so there is probably a ripe market for more snake oil motor mounts.
If my cynicism is unwarranted, please post some data so I can eat my shoe. Otherwise I might have to start selling vibration mitigation stickers (VMS)...
Hi Frederic,
In particular several quadcopter operators especially those with unusually large slow props are seeing "unusual" larger than normal Z axis vibrations especially when applying throttle wither to climb or stop a descent.
In my case On my Hoverthings Flip FPV Pro G with extended arms and 14" props (which only have 1/8" tip clearance at the sides) I have a very nice clean hover, but when I climb I get higher than normal Z axis vibrations.
This also coincides with my not gimbal mounted Sony AS100V displaying pronounced jello.
I surmise that it is likely that the larger (slower) props asymmetric blade position in addition prop tip proximity creating turbulence might be responsible for producing out of phase stability corrections actually increasing rather than damping Z vibrations temporarily.
You can also hear this during flight, nice smooth relatively quiet hover, choppy, loud during throttle application.
So yes, not only translational, but possibly self augmenting or sympathetic vibration.
Copters with smaller faster propellers and greater tip clearances do not seem to exhibit this phenomenon or at least not as pronounced.
Big props (with matched motors) are the best way to increase efficiency and flight time, but they are not without pitfalls.
I will be dropping back to 13" props myself from which I expect a 5 to 10% reduction in flight time, but the extended flight time doesn't do me any good if my video looks like #$%@.
My friend Oliver's otherwise identical copter has 13" props and these problems are minuscule for him and were completely compensated for by including a couple 1.25" Sorbothane hemispherical dampers between the live and solid portions of the frame (Sorbothane is a great multifrequency true damping medium).
Best Regards,
Gary
I am more into fixed wing but thinking about the potential sources of vibrations on a multicopter I find that even if you have perfectly balanced motors and propellers there are flexion and torsional vibrations that should be generated. the vibrations should be larger during translation so I was just wondering if that was what was observed if you record the vibrations during flight
Frederic, I am not sure if I understand your question. (Great first namee btw)
I will post a video about the function. Will have the second alpha product ready today and should have time to get some video of how they work up in a few days
Thanks for sharing, but I don't quite understand... how exactly does this work to mitigate vibrations?
as you are talking about vibration , is the amount of vibration the same during translation and while hovering on a multi rotor?
sure, happy to help, do you have pictures of your assembly or of the arm booms and how they connect to the frame, I have a few different ways I have mounted the blocks
Hi FC!
Since recently I've been working on building a frame for MiniQuads and Pixhawk as flight controller, so my nightmare has been with the vibrations that produce brushless motors and I've managed using the 42Hz value in the parameter "ins_mpu6k_filter "., besides that I had to play with the values Rate Roll P, I and D and Rate Pitch P, I, D, to stabilize the multirotor and still have issues with Loiter and PosHold anyway, I've been looking for practical solution for all this, and I hope your project can help enough.
I need to get the denier of the rubber used on this last run, I had allot of it as scrap so where I started. I need to get pictures of them in place, and just had this rendering ready and wanted to post before I made another production run. I made also a modification of the design so that it would fit better on the frame plates I am using... Should get these up in the next few days I hope, if I forget to post here I will make a page for them on Digi-DNA.net also
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