I currently have a hobby king DJI clone framed quad, but plan on designing a custom frame in the near future. One key design feature of this quad frame will be that the motors' vibrations are to be isolated from the rest of the frame, rather than having only the APM isolated from the frame. I plan on using the same motors/props, so I was going to find a spectrum on my current quad using my smartphone and a vibration app, but I'm not sure the app acquires data fast enough to give accurate resolution for the high frequency of the props. I know I've seen people who have done vib analyses on their copters, so I was wondering what people have done in the past that has worked. Any ideas?
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Fully with you in damping the vibration nearest to its source.
I would google for "sound card spectrum analyzer" and mechanically attach a light microphone to the frame. That would be cheap and will give you a baseline to start tuning the mounts. I have not been using those for years since I do have an oscilloscope with basic spectrum analyzer in it.
One example: http://zelscope.com/
-mikko
I found a different android app called "speedy spectrum analyzer" that does FFT based on the noise from your microphone instead of the accelerometers. It costs $5, and I'm sure there's a free one if you do some looking, but the real point is that it at least gave me some useful frequency data.
I'm going to try to design the filter based on what I have, then bench test the new design against the old design with an arduino (nano, probably) and an IMU to validate. I'm sure the code to get the accelerometer data from the IMU is pretty simple, but I'm also sure it's already out there (and I don't have any experience coding for Arduino). Anyone have a simple code solely for recording the accelerometer data and time?
Vibration Analysis Charts.pptx
I've been playing around with an app called VR mobile (Vibration Research). It has a strobe function that can provide some interesting subjective data, you don't get any numbers, but your eye can easily see when things are smooth.
Check this vid out, kind of scary to see!
Hard to do without instrumentation!
One could get dampers of differing durometer and see which one yields the most solid image?
Prop/Rotor balancing is obviously important