I Have inserted the starting pass at a much needed section on Vibration Control in the ArduCopter Wiki and would very much like feedback for corrections or additions from you all.
This is the close coupled mount that I use on my little F330 Flamewheel.
To achieve this plus and minus one tenth G vibration dampening.
In any case, please review the Vibration Control Wiki section under Assembly and give me some (constructive) feedback.
Thank You,
Gary McCray
Comments
Hi Robert I am planning on trying as many combinations as I can and that is certainly one of them.
I am planning on publishing Accel graphs for everything I try.
I have just cut out 2 3 inch squares from some lovely old 1/8" red linen reinforced phenolic electrical mounting board I had lying around. Nice high mass, very stiff, completely insulating and non electromagnetically interfering.
One of them will be for suspended mount (which I have respaced to fit) and the other for grommet mount.
We will see.
F11, why not just mount the naked APM onto the avionics plate using the blue grommets before you do anything else? that is what is intended with the design, and I had no issues with it.
I actually designed the airframe with integrated vibration mounts for an APM. Something most designers don't do. You should take advantage of it. ;)
The case doesn't really do much useful anyway. I'll tell you, after freefalling for 300 feet, landing straight upsidedown, the APM2 is actually still functional. So, unless you plan on crashing that hard, don't worry about the case. It's just not needed when you have a properly engineered avionics section. ;)
If you really want to go nuts, the most logical thing to do would be to put some isolation between the main frame section, and the entire avionics section.
As for Simon's results, yeah, that's what happens when you have a bit of mass on the APM side of the isolation. I've been saying this for almost a year now. ;)
Hi F11, Ive been looking at Amazons Sorbothane too.
I'm Specifically looking at these 30 durometer bushings: http://www.amazon.com/Isolate-It-Sorbothane-Vibration-Isolation/dp/...
I think 30 Durometer will be better for our use than 50. They also have it in sheets that can be cut into pads.
Hi Josh, Looking forward to it, I'm planning on testing some secondary isolation on both a O-ring suspended and a Vibration Grommet supported intermediate plate and I'd like to know if Moon Gel is worth trying.
This is something I'm going to try on my octo. I will use the 2.5 case with it's anti vin mount but just this to mount the case to the plate on the octo. First I will test with just double sided tape or nothing to get a starting point.
http://www.amazon.com/s?ie=UTF8&keywords=sorbothane
Hi F11, Done McMaster AntiVib Washer link is in the Wiki AntiVib section now. Get the lightest weight .3 lb ones in blue high recovery rate.
From what I understand at least in the US now you can deal with McMaster direct now without a business association and they only charge tax in 4 or 5 States.
Hi Jim, I like Manfred's Ear Plug Solution too and from looking at your graph it certainly looks like about 2.5 + and - and since you ran a standard deviation on it at 2.46 (which is an excellent technique) sounds right and 0.25 G is certainly adequate.
A 3/16 steel plate does seem like it might be a bit excessive and It seems like it might interfere with the APM's built in magnetometer, just a thought.
And Simon, as Hugues has also proven, the way to lowest vibration is a dual mode approach with an isolated intermediate plate and then the APM isolated on top of that. You are definitely down in the sub .01 G range.
Just a thought though, the primary foam pads you are using under the whole case look like they could permit a fair amount of physical movement of the whole flight control board under normal flight maneuvering conditions.
This might lead to a bit of a delay in the sensors following actual flight motions.
Just a thought, you'd have to be the judge of that.
The basic goal is to have the board move as little as possible in relation to the airframe while having it move just enough to soak up all of the vibrations.
Iv'e mentioned Catch-22 before in relation to this.
Still, great results and if sensor delay isn't a problem I'd say you have the vibration issue solved.
On my Flamewheel 450 I have all the electronics mounted within a CD case, as many others do. In my construction this case fixes to the main chassis with four foam rubber mounts. These are glued to the base of the CD case (which is reinforced with a disc of 3mm acrylic) and attached to the chassis with Velcro – see pictures.
The APM 1 is secured with 3 of the usual anti-vibration rubber bushings.
This gives me a double chance of dampening any vibration from the main frame and allows the expensive part of the Quad to detach in the event of a major crash.
Since I read the wiki on vibration issues I thought I’d see how well this mounting arrangement coped; here are the results.
You can see clearly the start sequence from arming, prop start and rev-up to take-off. The whole flight lasted about a minute to collect data. Measured vibration seems to be <0.1g for all three axes and usually below +/- 0.05g.
Props are balanced 10x4.5 APC, motors are Turnigy 2836 which have not been balanced.
Seems OK.
Thomas, thanks for that link at digikey! That's fantastic! I wanted to get shoulder screws like that, but they are ridonculously expensive at McMaster.
One issue though: The steel screws will cause mag interference on the board if you are using the build in mag... I use the blue grommets with nylon screws, nuts and washers.
Great and this link above would be good to add also.
http://www.mcmaster.com/#vibration-damping-grommets/=lk3num
Those are nice motor mounts Dany Try this link: http://www.mcmaster.com/#vibration-damping-grommets/=ljy64x
And look at part numbers 9311k64 and 9311k35, you want fast recovery and these are the lightest ones, still a little heavy, but probably if used with a secondary Alpha gel, silicone or Sorbothane foam pad under the flight control board would achieve decent results and should be less than 0.1 G vibration amplitude possibly even < 0.05 G.
Hi F11, those are directly linked on the Vibration Control section of the Arducopter,
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