This is very exciting research! I would love to know more about resonance in whoop frames if you ever have time time and interest. I would be especially interested to see data for the Beta85X frame with 2" props, 1103 motors, and battery on bottom (450-650mah 2S). That's the formula I nicknamed the "ShutterBug 85". It's still one of my favorites, and we have a local club that still races them (or would if not for COVID). I believe the frame is made of nylon, so it would be very different from the frames you have analyzed so far. It is also possible to add a carbon fiber X brace on the bottom of the frame. It would be super interesting to see the resonance behavior with and without that brace. If this is a project you think you would be interested in, then let's talk! There's an email on my channel's about page. I can get you BB logs too of course. Thanks for what you're doing! Keep it up!
This 100Hz vibration makes the craft sounds a lawn mower flying. This happens to helicopter's tail motor too. I use the 3-inch racer quad petrel 136's motor on my 249 gram helicopter. And I can see the tail fin vibration like a tuning fork at 120 Hz. If I change the motor to 4-inch racer quad motor (GepRC 1404), the oscillation frequency shifts to 180Hz.
I got a 3.5 inch bnf micro from avant quads and the reason they told me it did not have rpm filtering and bi directional dshot like most of there quads is because this particular one had a ton of mid range oscillations that they were unable to correct. Then proceed to tell me of a se version that was coming out with different motors that did have rpm filter and everything set up. This was crazy to me. Now I understand better I think 🤔 lol
What do you mean by "lighter motors"? Less powerful ones, or less heavy ones? Also, I'm also developing my frame and running some ANSYS analysis, let´s see how it goes. Thanks for the video and the inputs!
Lighter weight. Less mass on the end of the arm will increase the resonant frequency. You are fortunate to have access to Ansys, I used to have it at work but not anymore.
Thank you for this useful tip! Can frame resonance cause yaw twitches? I have a 4 inch light quadcopter (toothpick style) that I love to fly but I have this problem which I cannot solve. Unfortunately I don't have the blackbox logging on the fc. On hover and full throttle is very stable but at some point it start twiching only in yaw axis. Thanks! PS: I hope there will be an AOS T4;)
Thank you for this. If we observe the noise of oscillation at the 141 frequency, and then swap out the motors for lighter ones, replace the arms with thicker arms (likely change frames altogether), and install braces, would the quad not suffer other performance challenges, and possibly have throttle noise at a different frequency? Seems like all the effort to tune via P.I.D.s, rates, and filters solve a problem, but create new problems. Is there a frame, motor, fc combination that addresses these challenges by design, one that you fly yourself, or recommend for others; especially of advanced beginner to intermediate skill? If you have time, please reply.
Hi Richard, I have specifically designed a range of frames that have excellent vibration performance. They are much stiffer in certain directions than standard frames and this allows more agressive filters and PIDs to be used. You can check them out here: www.aos-rc.com While you can never eliminate resonance and vibration you can increase the frequency and reduce the amplitude through better frame design.
I wonder if its to do with how fast the motors can ramp up and down or the response time of the PID loop that governs the actual frequency of the MTO rather than the noise frequency.
@@ChrisRosser right, yes. that's certainly what dictates propwash freq, though the peak freq at which it occurs rises a bit with higher P for example, but there seems to be a limit (~40-70hz) across most rigs. reducing phase delay sometimes helps but sometimes seems mostly unrelated, which can be very frustrating. So there seems to be possibly more than one mechanism. in some cases messing with esc pwm seems to help. MTOs are also sometimes accompanied by jello which always suggests higher freqs at play as it distorts the sensor-sampling within a given frame. so like the top portion of the sensor would be sampling the image at one point in time, then by the time the lower portion samples the image it has change position on the sensor (because of vibration) resulting in this "jello" as it's called. I've ordered the AOS 5 and I'm very excited to see the spectrogram. I hope you're on to something! :)
I have two TBS Source one v.4 frames and have oscillation on both. I have already exchanged F4 for F7, Bhelis for bheli_32, on each quad I have different motors. And i get the jello effect all the time. I am still looking for the best configuration. thnx
@@ChrisRosser seriously, far humor... 420? 🧐 No disrespect, still working backwards through your channel and it's all very professional... You don't give off the, outward, 420 vibe. Thank you for sharing.
Basically the best way around with a cheap floppy frame is double the arms(sandwich them) Or just buy AOS frames, the man☝️knows his art and there is no shame in that.
This is very exciting research! I would love to know more about resonance in whoop frames if you ever have time time and interest. I would be especially interested to see data for the Beta85X frame with 2" props, 1103 motors, and battery on bottom (450-650mah 2S). That's the formula I nicknamed the "ShutterBug 85". It's still one of my favorites, and we have a local club that still races them (or would if not for COVID). I believe the frame is made of nylon, so it would be very different from the frames you have analyzed so far. It is also possible to add a carbon fiber X brace on the bottom of the frame. It would be super interesting to see the resonance behavior with and without that brace. If this is a project you think you would be interested in, then let's talk! There's an email on my channel's about page. I can get you BB logs too of course. Thanks for what you're doing! Keep it up!
+1
Greetings from Brazil. This video solved my drone's vibration problem.
Great video, Chris.Thx
The more of these resonance modes that I watch, the more it seems the quads are trying to flap like birds..
I think it's time for bed.
This 100Hz vibration makes the craft sounds a lawn mower flying. This happens to helicopter's tail motor too. I use the 3-inch racer quad petrel 136's motor on my 249 gram helicopter. And I can see the tail fin vibration like a tuning fork at 120 Hz. If I change the motor to 4-inch racer quad motor (GepRC 1404), the oscillation frequency shifts to 180Hz.
If we do not use black box. How can we tune to try to lower these oscillations?
I got a 3.5 inch bnf micro from avant quads and the reason they told me it did not have rpm filtering and bi directional dshot like most of there quads is because this particular one had a ton of mid range oscillations that they were unable to correct. Then proceed to tell me of a se version that was coming out with different motors that did have rpm filter and everything set up. This was crazy to me. Now I understand better I think 🤔 lol
What do you mean by "lighter motors"? Less powerful ones, or less heavy ones? Also, I'm also developing my frame and running some ANSYS analysis, let´s see how it goes. Thanks for the video and the inputs!
Lighter weight. Less mass on the end of the arm will increase the resonant frequency. You are fortunate to have access to Ansys, I used to have it at work but not anymore.
every 5inch quad I built gets this with any frame... however the oscillation is in the yaw axis...
Lighter motors means in weight? Or lower kv?
Lighter weight. That will move the resonance higher in frequency which is better.
Thank you for this useful tip! Can frame resonance cause yaw twitches? I have a 4 inch light quadcopter (toothpick style) that I love to fly but I have this problem which I cannot solve. Unfortunately I don't have the blackbox logging on the fc. On hover and full throttle is very stable but at some point it start twiching only in yaw axis. Thanks! PS: I hope there will be an AOS T4;)
Which stringer do you mean? Thanks buddy
A piece of carbon running from front motor to back motor.
Thank you for this.
If we observe the noise of oscillation at the 141 frequency, and then swap out the motors for lighter ones, replace the arms with thicker arms (likely change frames altogether), and install braces, would the quad not suffer other performance challenges, and possibly have throttle noise at a different frequency?
Seems like all the effort to tune via P.I.D.s, rates, and filters solve a problem, but create new problems.
Is there a frame, motor, fc combination that addresses these challenges by design, one that you fly yourself, or recommend for others; especially of advanced beginner to intermediate skill?
If you have time, please reply.
Hi Richard, I have specifically designed a range of frames that have excellent vibration performance. They are much stiffer in certain directions than standard frames and this allows more agressive filters and PIDs to be used. You can check them out here: www.aos-rc.com
While you can never eliminate resonance and vibration you can increase the frequency and reduce the amplitude through better frame design.
fascinating stuff! one thing that always confuses me here is that MTOs are also highly correlated with much lower freq than this (sometimes
I wonder if its to do with how fast the motors can ramp up and down or the response time of the PID loop that governs the actual frequency of the MTO rather than the noise frequency.
@@ChrisRosser right, yes. that's certainly what dictates propwash freq, though the peak freq at which it occurs rises a bit with higher P for example, but there seems to be a limit (~40-70hz) across most rigs. reducing phase delay sometimes helps but sometimes seems mostly unrelated, which can be very frustrating. So there seems to be possibly more than one mechanism. in some cases messing with esc pwm seems to help. MTOs are also sometimes accompanied by jello which always suggests higher freqs at play as it distorts the sensor-sampling within a given frame. so like the top portion of the sensor would be sampling the image at one point in time, then by the time the lower portion samples the image it has change position on the sensor (because of vibration) resulting in this "jello" as it's called. I've ordered the AOS 5 and I'm very excited to see the spectrogram. I hope you're on to something! :)
I have two TBS Source one v.4 frames and have oscillation on both. I have already exchanged F4 for F7, Bhelis for bheli_32, on each quad I have different motors. And i get the jello effect all the time. I am still looking for the best configuration. thnx
From second 0-5, which is call mid throttle osci?
How can I contact you? I have an idea that you might like for your frame.
I think I had a huge epiphany watching your videos about resonance, I'm curious what you think about it.
Reddit, Far_Humour_420. Let's chat!
@@ChrisRosser seriously, far humor... 420? 🧐 No disrespect, still working backwards through your channel and it's all very professional... You don't give off the, outward, 420 vibe.
Thank you for sharing.
🥸💨😶🌫️👽🍕
Basically the best way around with a cheap floppy frame is double the arms(sandwich them) Or just buy AOS frames, the man☝️knows his art and there is no shame in that.