About how longer logs exaggerates noise graph, there really should be a standard to do noise analysis. My standardised noise analysis is a 30 second flight with cruising around once, 4 flips and rolls in each direction, and finally 2 full throttle punch-outs. This will give full spectrum noise profile that covers nearly every quad movement. The result will also be comparable between setups.
As long as you are doing a consistent flight between all set ups you're in the clear. I will say though, I don't think 30 sec is enough, 2 min seems to be the standard for most ppl that know what they're doing, i.e, Spatz, the BB log FB group, etc. What you're missing from your log: scaled throttles, throttle pumps, induced prop wash
It actually depends on the objective of the logging, @@srossi88. For tuning, more flight time is better because the log accumulates every possible vibration characteristics. For comparing setups, each flights need to be identical, and the longer flight will induce more unwanted variables. Scaled throttle, throttle pumps, and induced propwash are subject of PID tuning, not vibration characterisation. Even a single punch-out already show vibration characteristics in the entire throttle range, that's what we care the most in filter setup.
Glad to hear that you found it valuable. I'm going to do a proper filters video soon as part of my perfect AOS 5 build hopefully there will be more useful stuff in there for you!
Excellent Video once again! @ChrisRosser Have you ever simulated tubular Arms and/or structural TPU?
3 года назад
@@ChrisRosser It's another excellent video and hopefully i can apply some of this to my tune once im done building the qav-s, out of curiosity have you found another 5" that performs better?
@@ChrisRosser - Great video! I've just built my first 5" quad using this frame and am slowing learning about tuning with the help of your videos and others. Can these recommended filter settings apply to any build using the QAV-S (JB) frame or does it make a difference with different components? I have different motors, 4s build, some TPU protective parts for now. Interested to know if your settings will still apply. Cheers!
I'm so glad that I found this channel, you explain things so very well. I have the standard QAV-S, and I already had it tuned pretty well but after applying your filter suggestions I have been able to eek out that last little bit of performance our of my build. Please continue doing what you are doing good sir, top tier stuff 👍
I just finished tuning my regular QAV-S using all your recomendations, and finally it flies great. I can force the quad to propwash and it can barely be seen. It sounds , but on video it's mostly unnoticeable. I managed to reach a D term of 40 , and yet havent applied the grease, Im happy with this tune. Tanks for sharing your knowledge. I have tuning by ear since my fc blackbox dissapeared with bf4.2 I hope the manufacturer fixes it soon
Chris, this was thoroughly enjoyable. I sold Finite Element Analysis for IBM in 1981 and 1982. We sold Structural Dynamics Research Corp code along with Dassault's CATIA and Lockheed's CADAM. We sold multi-million dollar mainframes dedicated to running 3D CAD and FEM! I loved your explanations! Very well done! Thank you!
Filters won’t fix a bad frame, but they’ll make a good frame great - so this is huge. Hope to see more of these and seriously, you’re such a credit to the community for doing this - thank-you
I am very surprise for what you said about the log. I did imagine amplitude in logs are normalised to log duration ! Thanks for all your vidéos, I love them
Yeah, you would think they would be normalised but they are not. The longer the log the more noise you see. It's not an issue if you are expecting it and you can use 'i' and 'o' on your keyboard to trim a log in bb explorer.
Thanks for taking a look at this! It's interesting, because you ended up at almost exactly the same place on your filter recommendations as where I am! I will do a tiny bit of nitpicking on the Dterm comments though. I actually tend to run lower Dterm because too high Dterm makes the quad a bit sluggish on snap moves, to which I am a bit partial. Anything above about upper 40ish low 50ish for dterm adversely affects handling in my opinion. I can already push P values to ridiculous levels without adverse effects with the correct filtering with the Dterm around 48-51 range. We also consciously decided against increasing the thickness of the arms due to that being a significant contributing factor to the weight of a frame. The resonance response is already in a realm that is very serviceable so the tradeoff between weight and rigidity came down on the weight side for this application. The target was to keep the frame below the 115g mark and we hit it right on. Thanks again for your work! The filter recommendations are fantastic!
Thanks for providing the CAD Ryan! I'm not surprised that we agree on the filter recommendations. Regarding the D Term: I typically run D gains above 50 on all my builds. I then use the Dmin as a D boost to enable D to go even higher on snap moves. To prevent any sluggishness you need to increase P gain and Feedforward proportionally to D. That way even though the D term is fighting harder FF and P are pushing that much harder too! Once I have found my PD ratio for critically damped behavior I just crank P and D up together maintaining the ratio until D noise stops me pushing D any higher. Once there I use D min as a D boost to enable D to go even higher on snap moves until I get twitches in steady flight (then back off 5-10%) and I keep pushing P up to maintain the ratio for the boosted D value. Then I add as much feedforward as I need to overcome the D term when kicking into snap moves. You need *a lot* of feedforward (300+) with high D gains to track setpoint but just keep cranking it up until gyro follow setpoint on snap moves.
@@ChrisRosser When I tune like that I always end up feeling like it's a bit overly stiff and over tuned. I do use Dmin, usually leave it on defaults though and just adjust the D slider to put the D values in the upper 40s/lower 50s. I'm also not a huge fan of the stick feel with super high FF either. Usually end up with about 150 maximum, depending on the quad. I think the new fixes in the RC rate and filtering side of things will probably solve the issues I've had with very high FF, so in 4.3 with the new RC code, I'll probably give your technique another go. I will say the tuning window has gotten ridiculously wide, where you can get something that flies reasonable on a huge range of PID values these days. In some ways that almost makes it harder to tune, since the changes are often more subtle than obvious.
@@QuadMcFlyFlies If you are finding the feel is not as you like it that points to rates I think. I think a lot of people tune their rates based of BF stock PIDs and filters and therefore don't realise they have a bunch of slop built in to everything. Once you have a tightly tuned quad you have to go back to the rates and reduce your center stick rates and often increase your RC smoothing a little to soften up the feel back to where it was with undertuned PIDs. I have different rates for BF stock and tuned quads. I hate how my BF stock rates feel on a tuned quad. They are just way too twitchy.
Solid. It was fun to watch the final harmonic chord rendered in 3d. the image of ones ears' wiggles in the presence of such frequencies was inescapable...
Awesome analysis! I wish there was similar information for other frame designs. I can’t wait until Joshua applies your advice and hopefully, your analysis of the subsequent black box data.
Another great analysis Chris. I just finished a build of the JohnnyFPV edition of the QAV-S with PG44a applied to everywhere you recommended. Hoping to take out for it's first flight this weekend. I'm interested to see how the blackbox data I get compares to what you've shown here with the JB edition.
I am kind of puzzled by your third suggestion (static dterm lowpass). Frame resonance is to the best of my knowledge best addressed with static notch filters. Those offer a nicer 'price'(=latency) to performance ratio than simple low pass filters. Is there a specific reason you decided not to use static notches that sit on the resonance frequencies? Based on this data I would have suggested to just use the static notch filters and keep dterm lowpass dynamic with a high cutoff (in addition to your point 1 & 2)
Yes the filter suggestions are an amazing resource. Did you do this for the Apex resonance analysis? If not could you share your suggestions somewhere? I'd love to hear your thoughts and see how close my filters are
@@ChrisRosser yes absolutely, I have a new frame coming and I can put new motors on it as well. I have one with air unit and one with a vista but Whatever specific requirements you need to help please let me know and I'll see what I can do.
I would love to see this on another one of Ryan’s designs. The xilo Blue Hornet. Very good flying frame atleast from a physical standpoint. It’s been very solid for me. The 30* angled body seems to have eliminated I term wind up on the pitch axis all together
Great Analysis! Since you mentioned the length of the blackbox log being a variable, I would think going forward it would be best to request all black box logs to be the same length for a more controlled analysis. Keep up the great contact! Or maybe it’s possible to trim the log lengths to be the same? I’m not sure.
I have this counter intuitive phenomenon that mounting the motors on silicone gummies (with steel m3 screws though) in fusion 360 it introduced some around 50Hz modes where as fully rigid frame had 110Hz lowest modes. I would have predicted that this would have clipped high frequency modes effectively off but this didn't really happen. It might be that the propagation of the vibration didn't penetrate as deep into the CG as before but I suppose really low modes could be harder for the FC to deal with.
You should od a Nano Long Range/Rekon 3 vibration analysis. I think it would be really interesting, and I feel any optimizations with PID tuning could help battery life massively
Chris, how does this compare to the Apex and even the AOS 5? BTW I believe every frame designer should consult with you so that their patrons can optimize the tune when they build. I'm in the process of building an AOS 5 but this frame is my second to build right after. I have two QAV-S 4" and they fly great.
Speaking *only* in terms of vibration performance: The Apex has a bit of an advantage over the QAV-S due to its 5.5mm arms but it's also heavier. The AOS 5 is really optimized for resonance performance and runs 6mm arms so it pulls ahead of both by a fair margin. It weighs 115g which is a little more than the QAV-S I think but still less than the Apex.
@@ChrisRosser What about adding a layer of rubber between the motor and the arms? Or between the arms and the center plates? How would that affect things?
@@longboarderebright He's making a 5.5" AOS frame after having received MANY requests. My understanding is that it's in the prototype/testing stage right now. That's the frame I'm waiting for myself...
Mathematically you can't! A low pass filter tries to do what you suggest but it can only attenuate higher frequencies. Nothing can just disregard them.
Hi Chris, great stuff from a fellow engineer :) Living in suburbs I am more tempted by sub250 builds. In that regard, do you have an opinion on the 2fiddy 4S? I remember your golden prop size for 250g kwad is around 3,5" but the 2fiddy seems to be an exception. Wonder how it performs in terms of resonance. Take care and keep up the good work! Would enjoy to have your science work on sub250g also :))
Erm are you recommending disabling the gyro low pass filters assuming people have RPM filtering enabled? Otherwise people might start smoking motors if they have crap motors and props.
I wouldn't want to assume that, you are right that you need those active! The second suggestion is to make sure gyro and dynamic notch filters are active down below 160Hz to capture the resonant peaks. If they are set up that way the risk of smoking motors is minimal I think.
Wow - you're receiving participation from some of the industry heavyweights (which I wouldn't necessarily expect, especially since the results might not be entirely flattering). How long before you can quit your day job and just become a full-time FPV engineering consultant?
I'm not interested in somebody flattering me. When somebody as knowledgeable as Chris offers his time for free, you say yes :-) This analysis is gold, and if it had pointed to a flaw in the frame, I would have welcomed the opportunity to fix it.
Hey Chris, thanks so much for the content you put out. It’s very useful, even to an average hobbyist like me. I received Joshua’s frame today and I’m excited to build it out but I’m also looking forward to receiving your AOS5 frame. It’s amazing how much you’ve advanced the ability to analyze the characteristics and performance of these frames. Thank you.
This is very informative thank you! I’m curious if there’s any correlation between this 5” version and the 3” version of qav-s mini frame, considering they are of similar construction. Sorry if it’s a noob question as I’m not familiar with materials.
some reason I get terrible experience with this frame. First build was BF 4.4 than rebuild with FetTec G4 - but in both cases - hard to tune. I also have QAV S V1 - it works much better
I am watching this video and reading one article per day , UNTIL I F****** UNDERSTAND all of this.....I can't stand not bring able to tune my quads anymore. I understand the filters ok at this point. But I don't understand changing PIDS after getting my filters right.
Chris, are you using the forces of motor precession as an input? I believe certain modes should be driven by gyroscopic motor precession, rather than tangential oscillation.
I'm not taking the gyroscopic nature of the motors into account at this stage. However, agreement between my models and real world testing are now within 5% so I am confident the model is fit for purpose.
@Chris Rosser I have 2 of the Bardwell Xilo Beginner quads. Do you have any interest in running an analysis of this setup? I believe there are a LOT of this build flying around as the kit constantly goes out of stock at GetFPV. I have an OpenLager attached to one of my quads and can provide bb logs if interested. Also I have a tube of the damping grease that could be applied to one for A/B testing :) Right now I'm running UAVTech's 5" base tune plus Krunked's betaflight 4.2 tune from the betaflight community git.
Yes it does matter. Most typical frames are made with T300 standard layup carbon fiber for a balance of durability and stiffness. The properties of that material is reasonably consistent frame to frame in my experience for quality frames like this one.
Does the centre of gravity have any impact? Kinda curious about the effect the battery may have - if it's weight/position acts to damp any of the vibrations at particular frequencies (pendulum effect)?
+1 had the battery rotate slightly while strapped on the other day, by just a few degrees to the side, clockwise. It was enough to cause motor flutter sounds upon pushing the quad, as it probably caused too much noise in the otherwise acceptable D term. So battery definitely must have an impact, not sure which one though.
Hi, anyway we could perhaps put in layman terms... I enjoy and appreciate the science but maybe its too much info on pros and cons , is there no happy medium for quads?
There is definitely a happy medium. The difficulty is that the ideal setting is different for different pilots and flying styles. I tune very agressively for the best flight feel. Others may prefer a softer tune so they can fly even with damaged props or older frames.
Surprised with all the detailed videos you make, you haven't once mentioned (that I can find) HOW the flight controller receives the motor frequencies. I thought for sure this video would, but I didn't see it anywhere.
Oh come on Chris dont tease us like this , we want to see the AOS5 flying !!! someone should make this meme popular , "All frame designers gangsta , until Chris comes with his resonance analysis"
It's coming after the filter and tuning videos in the next couple of weeks. Hopefully some other people who've ordered the frame can show some flight footage too!
@@ChrisRosser I only ask because you mentioned adding more material to the arm would cancel out most of the vibrations I'm sure u meant more towards the middle of the arm tho right because the horms are on the end
@@runpuppyfpv5744 Yes you're right. if you look at the stress results you can see where the material should be added. Its in the middle of the arm. The end would do nothing.
is there any video to avoiding hot motors with the filter such as in firmware FalcoX instead of betaflight,,i guess it would be interest subject if someone like your background can give us from the side of your views between betaflight, kiss, Falcox, emu..or the worlds need new firmware or new brushless motor winding desain
Hello Chris i design my frame but im 13 so i dont now all about phisics and frame resonance so if you can help me i would appreciate thank you in advance
Hi, I'm happy to hear you are thinking of designing your own frame. I am not able to help people individually at the moment but I hope you watch all my videos and they help you!
@@ChrisRosser Great in dept analysis! I own this frame as well as I test out Ryans pre-protype frame, only for 7 inch though, where we get mostly a 300khz frequency filtered out.
I know the video is old but i have the same frame and i just cant tune it right. Ill be very happy if someone helps me with some pids and filters screenshot or something so i can finally enjoy my flights with this drone ;(
The graph is from betaflight blackbox explorer. If you are unfamiliar with this software there is a video series on it here: ruclips.net/video/VEALlGlcPbw/видео.html It's a very useful tool for tuning quadcopters. I hope you find it useful!
Not in an apex. How do you mean every frame. Or is that just to excuse the frame for having resonance. What’s more important here. Your collaboration with bardwell or the facts. Aint no spikes on pex. None
Some builds with the Apex frame do have significant resonance peaks. And the Apex is quite a heavy frame (125g), it's easy to improve resonance performance if you make the frame 10% heavier. Not knocking the design of the Apex, it's a well thought out frame, just the facts.
![Twenty One Pilots - “The Line” (from Arcane Season 2) [Official Music Video]](http://i.ytimg.com/vi/E2Rj2gQAyPA/mqdefault.jpg)
You have a great gift for clearly explaining the subject. Thank you and keep up the great work.
Much appreciated! Thanks for your support.
About how longer logs exaggerates noise graph, there really should be a standard to do noise analysis. My standardised noise analysis is a 30 second flight with cruising around once, 4 flips and rolls in each direction, and finally 2 full throttle punch-outs. This will give full spectrum noise profile that covers nearly every quad movement. The result will also be comparable between setups.
As long as you are doing a consistent flight between all set ups you're in the clear. I will say though, I don't think 30 sec is enough, 2 min seems to be the standard for most ppl that know what they're doing, i.e, Spatz, the BB log FB group, etc.
What you're missing from your log: scaled throttles, throttle pumps, induced prop wash
It actually depends on the objective of the logging, @@srossi88. For tuning, more flight time is better because the log accumulates every possible vibration characteristics. For comparing setups, each flights need to be identical, and the longer flight will induce more unwanted variables.
Scaled throttle, throttle pumps, and induced propwash are subject of PID tuning, not vibration characterisation. Even a single punch-out already show vibration characteristics in the entire throttle range, that's what we care the most in filter setup.
The filter advice was seriously great! although I don't own this frame, learned a lot from this video and how I can improve my setup
Glad to hear that you found it valuable. I'm going to do a proper filters video soon as part of my perfect AOS 5 build hopefully there will be more useful stuff in there for you!
@@ChrisRosser Looking forward 👍
Excellent Video once again!
@ChrisRosser Have you ever simulated tubular Arms and/or structural TPU?
@@ChrisRosser It's another excellent video and hopefully i can apply some of this to my tune once im done building the qav-s, out of curiosity have you found another 5" that performs better?
@@ChrisRosser - Great video! I've just built my first 5" quad using this frame and am slowing learning about tuning with the help of your videos and others. Can these recommended filter settings apply to any build using the QAV-S (JB) frame or does it make a difference with different components? I have different motors, 4s build, some TPU protective parts for now. Interested to know if your settings will still apply. Cheers!
I'm so glad that I found this channel, you explain things so very well. I have the standard QAV-S, and I already had it tuned pretty well but after applying your filter suggestions I have been able to eek out that last little bit of performance our of my build.
Please continue doing what you are doing good sir, top tier stuff 👍
I'm so happy you found this useful!
I just finished tuning my regular QAV-S using all your recomendations, and finally it flies great. I can force the quad to propwash and it can barely be seen. It sounds , but on video it's mostly unnoticeable. I managed to reach a D term of 40 , and yet havent applied the grease, Im happy with this tune. Tanks for sharing your knowledge.
I have tuning by ear since my fc blackbox dissapeared with bf4.2 I hope the manufacturer fixes it soon
Great to hear! Thanks for your comment and I hope your QAV-S continues to fly great!
Chris, this was thoroughly enjoyable. I sold Finite Element Analysis for IBM in 1981 and 1982. We sold Structural Dynamics Research Corp code along with Dassault's CATIA and Lockheed's CADAM. We sold multi-million dollar mainframes dedicated to running 3D CAD and FEM! I loved your explanations! Very well done! Thank you!
Filters won’t fix a bad frame, but they’ll make a good frame great - so this is huge. Hope to see more of these and seriously, you’re such a credit to the community for doing this - thank-you
You are so right. What is the point of buying a good frame if you run it with the same filters and PIDs? 😁
You are on a roll, sir! Keep the awesome vids coming!
Glad you liked this one. Thanks for leaving a comment 😁
Thanks for all the work you do Chris.
My pleasure! Thanks for your support.
I am very surprise for what you said about the log. I did imagine amplitude in logs are normalised to log duration !
Thanks for all your vidéos, I love them
Yeah, you would think they would be normalised but they are not. The longer the log the more noise you see. It's not an issue if you are expecting it and you can use 'i' and 'o' on your keyboard to trim a log in bb explorer.
Thanks for taking a look at this! It's interesting, because you ended up at almost exactly the same place on your filter recommendations as where I am!
I will do a tiny bit of nitpicking on the Dterm comments though. I actually tend to run lower Dterm because too high Dterm makes the quad a bit sluggish on snap moves, to which I am a bit partial. Anything above about upper 40ish low 50ish for dterm adversely affects handling in my opinion. I can already push P values to ridiculous levels without adverse effects with the correct filtering with the Dterm around 48-51 range.
We also consciously decided against increasing the thickness of the arms due to that being a significant contributing factor to the weight of a frame. The resonance response is already in a realm that is very serviceable so the tradeoff between weight and rigidity came down on the weight side for this application. The target was to keep the frame below the 115g mark and we hit it right on.
Thanks again for your work! The filter recommendations are fantastic!
Thanks for providing the CAD Ryan! I'm not surprised that we agree on the filter recommendations. Regarding the D Term: I typically run D gains above 50 on all my builds. I then use the Dmin as a D boost to enable D to go even higher on snap moves. To prevent any sluggishness you need to increase P gain and Feedforward proportionally to D. That way even though the D term is fighting harder FF and P are pushing that much harder too!
Once I have found my PD ratio for critically damped behavior I just crank P and D up together maintaining the ratio until D noise stops me pushing D any higher. Once there I use D min as a D boost to enable D to go even higher on snap moves until I get twitches in steady flight (then back off 5-10%) and I keep pushing P up to maintain the ratio for the boosted D value. Then I add as much feedforward as I need to overcome the D term when kicking into snap moves. You need *a lot* of feedforward (300+) with high D gains to track setpoint but just keep cranking it up until gyro follow setpoint on snap moves.
I did the suggested filter settings and it flies amazing thanks so much for the hard work
@@ChrisRosser When I tune like that I always end up feeling like it's a bit overly stiff and over tuned. I do use Dmin, usually leave it on defaults though and just adjust the D slider to put the D values in the upper 40s/lower 50s. I'm also not a huge fan of the stick feel with super high FF either. Usually end up with about 150 maximum, depending on the quad. I think the new fixes in the RC rate and filtering side of things will probably solve the issues I've had with very high FF, so in 4.3 with the new RC code, I'll probably give your technique another go.
I will say the tuning window has gotten ridiculously wide, where you can get something that flies reasonable on a huge range of PID values these days. In some ways that almost makes it harder to tune, since the changes are often more subtle than obvious.
@@QuadMcFlyFlies If you are finding the feel is not as you like it that points to rates I think. I think a lot of people tune their rates based of BF stock PIDs and filters and therefore don't realise they have a bunch of slop built in to everything. Once you have a tightly tuned quad you have to go back to the rates and reduce your center stick rates and often increase your RC smoothing a little to soften up the feel back to where it was with undertuned PIDs.
I have different rates for BF stock and tuned quads. I hate how my BF stock rates feel on a tuned quad. They are just way too twitchy.
I just found you thanks to JB. Instant sub. Looking forward to watch all your vids.
Welcome aboard!
Always love watching your content. Every day is a school day! Thank you!
Glad you enjoyed this! Thanks for your support.
Bought the prebuilt & so far it's been great but looking forward to trying these suggestions out to get just that little bit more out of it.
Hope you enjoy it and it flies even better for you.
Solid. It was fun to watch the final harmonic chord rendered in 3d. the image of ones ears' wiggles in the presence of such frequencies was inescapable...
Awesome analysis! I wish there was similar information for other frame designs. I can’t wait until Joshua applies your advice and hopefully, your analysis of the subsequent black box data.
Another great analysis Chris. I just finished a build of the JohnnyFPV edition of the QAV-S with PG44a applied to everywhere you recommended. Hoping to take out for it's first flight this weekend. I'm interested to see how the blackbox data I get compares to what you've shown here with the JB edition.
I'm interested to hear how it goes. Hopefully it flies even better for you. You'll need to tune the PIDs aggressively to see the full benefit 👍👍👍
Great video. Is the settings you recommended the same on 4.3? Or can we add a second dynamic notch?
Would love to see a video like this about the 2fiddy
Same :)
I am kind of puzzled by your third suggestion (static dterm lowpass). Frame resonance is to the best of my knowledge best addressed with static notch filters. Those offer a nicer 'price'(=latency) to performance ratio than simple low pass filters. Is there a specific reason you decided not to use static notches that sit on the resonance frequencies? Based on this data I would have suggested to just use the static notch filters and keep dterm lowpass dynamic with a high cutoff (in addition to your point 1 & 2)
It would be interesting to compare it to the original QAV-S design
Yes the filter suggestions are an amazing resource. Did you do this for the Apex resonance analysis? If not could you share your suggestions somewhere? I'd love to hear your thoughts and see how close my filters are
I can certainly provide some filter suggestions for the Apex, could you send me a gyro_scaled blackbox log like JB did for the QAV-S?
@@ChrisRosser yes absolutely, I have a new frame coming and I can put new motors on it as well. I have one with air unit and one with a vista but Whatever specific requirements you need to help please let me know and I'll see what I can do.
I second this. The APEX is an amazing and very popular frame, so having this level of analysis on it would be absolutely outstanding.
Chris, first time visiting your channel...i subscribed! This is awesome stuff! Thanks!!
Great analysis! The filter suggestion section is a really good addition to the video. Hope you can go back and do that for the glide frame haha ;)
I would love to see this on another one of Ryan’s designs. The xilo Blue Hornet. Very good flying frame atleast from a physical standpoint. It’s been very solid for me. The 30* angled body seems to have eliminated I term wind up on the pitch axis all together
This is so awesome. Thanks for the great vid!
Glad you enjoyed it! Thank you for your comment.
Great Analysis! Since you mentioned the length of the blackbox log being a variable, I would think going forward it would be best to request all black box logs to be the same length for a more controlled analysis. Keep up the great contact! Or maybe it’s possible to trim the log lengths to be the same? I’m not sure.
I can trim them, I'll do that next time.
Interesting video. I can't help wonder, don't the weight and weight balance of the motors have a huge impact on how the frame resonates?
New Thumbnail made my Day Nice Video
I'm glad! Big thank you to JB for providing the thumbnail for his video so I could do that.
Great vid keep them coming👍
Thanks Steven!
Jb just put up flight with new filter settings. What a difference don’t watch just listen. Amazing.
Awesome video! Can you please make a 'shorts' type video with filter suggestions for the ImpulseRC apex? Pretty please with sugar lumps on top?:D
If you can email me a gyro_scaled log for your build I'd be happy to!
I have this counter intuitive phenomenon that mounting the motors on silicone gummies (with steel m3 screws though) in fusion 360 it introduced some around 50Hz modes where as fully rigid frame had 110Hz lowest modes. I would have predicted that this would have clipped high frequency modes effectively off but this didn't really happen. It might be that the propagation of the vibration didn't penetrate as deep into the CG as before but I suppose really low modes could be harder for the FC to deal with.
In your model did you apply preload to the screws? If not, that may be the problem.
You should od a Nano Long Range/Rekon 3 vibration analysis. I think it would be really interesting, and I feel any optimizations with PID tuning could help battery life massively
Chris, how does this compare to the Apex and even the AOS 5? BTW I believe every frame designer should consult with you so that their patrons can optimize the tune when they build. I'm in the process of building an AOS 5 but this frame is my second to build right after. I have two QAV-S 4" and they fly great.
Speaking *only* in terms of vibration performance: The Apex has a bit of an advantage over the QAV-S due to its 5.5mm arms but it's also heavier. The AOS 5 is really optimized for resonance performance and runs 6mm arms so it pulls ahead of both by a fair margin. It weighs 115g which is a little more than the QAV-S I think but still less than the Apex.
@@ChrisRosser What about adding a layer of rubber between the motor and the arms? Or between the arms and the center plates? How would that affect things?
Really like to see my rekon5 with out arm braces on analysis to see what it looks like when it is at the worse. And gyro filters
Thank you for the wealth of knowledge.
I was excited to get this frame.....until you released yours, lol!
The 5.5" 700gm version is still a month or two from release?
About a month. Maybe less!
@@ChrisRosser Cool, I should have the nyogel 767a by then 😃
@@ChrisRosser 5.5" aos5.5? or 5.5 qav? cuase i like my 5.5 frames!
@@longboarderebright He's making a 5.5" AOS frame after having received MANY requests. My understanding is that it's in the prototype/testing stage right now. That's the frame I'm waiting for myself...
@@TheDiegoAranda sicknasty!! i think ill be buying one of those for my next 5" build! if it can have a 30x30 stack im down
@Chriss Rosser thank you for these amazing videos. I wanted to know what you think about the Hyperlite Freerange frame?
I just built the Camera Butter Cinema ONE I would love to see resonates of this Canadian frame as I feel is a greatest design in 5yrs.
Fantastic content Chris! Do you think there is any value in doing a round up of motor vibe analysis?
great analisys!
Very interesting. I assembled my JB edition QAV-S with Nyogel 767A grease. I wonder how our data would compare.
I'd also be very interested to see too!
I wonder what effect adding a thin bike inner tube (instead of nyogel or tape) between base plates to isolate motor arm vibration.
I would love you to send some blackbox logs if you have them.
It's pretty windy out right now, but as soon as it settles I'll get some logs and send them to Chris for analysis.
So helpful, loving these videos. Have you done any tests soft mounting motors? Any difference in overall resonance?
I put PG44a grease under the motors. It works much more consistently than soft mounting and makes a big difference.
Great video!
About the d-term above 100hrz analogy , so why just not disregard all frequencies in d term only above that trashold ?
Mathematically you can't! A low pass filter tries to do what you suggest but it can only attenuate higher frequencies. Nothing can just disregard them.
Awesome content. Please, could you analyse the Moongoat frame from Rotor Riot? Thanks!
Great video thank u .
Glad you enjoyed it, thanks for the positive comment!
Hi Chris, great stuff from a fellow engineer :)
Living in suburbs I am more tempted by sub250 builds. In that regard, do you have an opinion on the 2fiddy 4S?
I remember your golden prop size for 250g kwad is around 3,5" but the 2fiddy seems to be an exception. Wonder how it performs in terms of resonance.
Take care and keep up the good work!
Would enjoy to have your science work on sub250g also :))
I'm afraid there are no exceptions to the physics. The potential of 3.5" is always more than 5" at 250g AUW.
@@ChrisRosser fair enough, any plan on having a 3.5" sub250 version of your frame then? :)
@@xnoux1 Absolutely. I've started the design already.
@@ChrisRosser you made my day :)
Erm are you recommending disabling the gyro low pass filters assuming people have RPM filtering enabled?
Otherwise people might start smoking motors if they have crap motors and props.
I wouldn't want to assume that, you are right that you need those active! The second suggestion is to make sure gyro and dynamic notch filters are active down below 160Hz to capture the resonant peaks. If they are set up that way the risk of smoking motors is minimal I think.
Wow - you're receiving participation from some of the industry heavyweights (which I wouldn't necessarily expect, especially since the results might not be entirely flattering). How long before you can quit your day job and just become a full-time FPV engineering consultant?
Hopefully never! I love my day job. This is just a bit of fun 😁 I'm glad you're enjoying it too.
I'm not interested in somebody flattering me. When somebody as knowledgeable as Chris offers his time for free, you say yes :-) This analysis is gold, and if it had pointed to a flaw in the frame, I would have welcomed the opportunity to fix it.
Hey Chris, thanks so much for the content you put out. It’s very useful, even to an average hobbyist like me. I received Joshua’s frame today and I’m excited to build it out but I’m also looking forward to receiving your AOS5 frame. It’s amazing how much you’ve advanced the ability to analyze the characteristics and performance of these frames. Thank you.
@@JoshuaBardwell is this black box sans nyogel? It would be cool to see a before and after on your frame!
This is very informative thank you! I’m curious if there’s any correlation between this 5” version and the 3” version of qav-s mini frame, considering they are of similar construction. Sorry if it’s a noob question as I’m not familiar with materials.
A long log feels good too 🤣
some reason I get terrible experience with this frame. First build was BF 4.4 than rebuild with FetTec G4 - but in both cases - hard to tune. I also have QAV S V1 - it works much better
Can you make a quick video showing where all these filter settings are changed?
A full run down of BF filter tuning is already uploaded and scheduled for release on Friday ;)
@@ChrisRosser your the man!
Blimey! when will understand more than 10% of this.. i feel i should have paid more attention in physics.
I am watching this video and reading one article per day , UNTIL I F****** UNDERSTAND all of this.....I can't stand not bring able to tune my quads anymore. I understand the filters ok at this point. But I don't understand changing PIDS after getting my filters right.
Chris, are you using the forces of motor precession as an input? I believe certain modes should be driven by gyroscopic motor precession, rather than tangential oscillation.
I'm not taking the gyroscopic nature of the motors into account at this stage. However, agreement between my models and real world testing are now within 5% so I am confident the model is fit for purpose.
Chris - can you give some FetTec GUI filter suggestion please. Maybe it can bring my build back) Thanks
@Chris Rosser I have 2 of the Bardwell Xilo Beginner quads. Do you have any interest in running an analysis of this setup? I believe there are a LOT of this build flying around as the kit constantly goes out of stock at GetFPV. I have an OpenLager attached to one of my quads and can provide bb logs if interested. Also I have a tube of the damping grease that could be applied to one for A/B testing :) Right now I'm running UAVTech's 5" base tune plus Krunked's betaflight 4.2 tune from the betaflight community git.
Is this a preset in betaflight? it should be, im sure he sold a boat load of diy kits.
is it possible to other firmware you may reviews,,such as falcox flightone
I presume the quality of the CF has some bearing on resonance of a frame.
Yes it does matter. Most typical frames are made with T300 standard layup carbon fiber for a balance of durability and stiffness. The properties of that material is reasonably consistent frame to frame in my experience for quality frames like this one.
Does the centre of gravity have any impact? Kinda curious about the effect the battery may have - if it's weight/position acts to damp any of the vibrations at particular frequencies (pendulum effect)?
+1
had the battery rotate slightly while strapped on the other day, by just a few degrees to the side, clockwise. It was enough to cause motor flutter sounds upon pushing the quad, as it probably caused too much noise in the otherwise acceptable D term.
So battery definitely must have an impact, not sure which one though.
COG really does matter as the bouncing mode couples onto pitch and roll if the COG is not centered.
hey Chris, can I assume the same reccomendations for the jhonny frame?
Yes you can.
Hi, anyway we could perhaps put in layman terms... I enjoy and appreciate the science but maybe its too much info on pros and cons , is there no happy medium for quads?
There is definitely a happy medium. The difficulty is that the ideal setting is different for different pilots and flying styles. I tune very agressively for the best flight feel. Others may prefer a softer tune so they can fly even with damaged props or older frames.
Could you look at the geprc mark4 frame? Would like to hear your opinion on resonance.
Check this out: ruclips.net/video/jKT4hk0L2Tc/видео.html
Surprised with all the detailed videos you make, you haven't once mentioned (that I can find) HOW the flight controller receives the motor frequencies. I thought for sure this video would, but I didn't see it anywhere.
The gyro picks them up as noise and bidirectional dshot also sends motor rpm data.
Oh come on Chris dont tease us like this , we want to see the AOS5 flying !!!
someone should make this meme popular , "All frame designers gangsta , until Chris comes with his resonance analysis"
It's coming after the filter and tuning videos in the next couple of weeks. Hopefully some other people who've ordered the frame can show some flight footage too!
What is in your opinion the best 7inch frame?
Would it be safe to assume that the QAV-S Johnny frame would be similar to this?
I think so yes.
Awesome content one question was that analysis done on the frame with the horns on the arms or on the frame everyone else got ?
The one everyone else got. But it makes absolutely no difference.
@@ChrisRosser ok awesome I did your suggested modifications with great results thanks for your support in our hobby
@@ChrisRosser I only ask because you mentioned adding more material to the arm would cancel out most of the vibrations I'm sure u meant more towards the middle of the arm tho right because the horms are on the end
@@runpuppyfpv5744 Yes you're right. if you look at the stress results you can see where the material should be added. Its in the middle of the arm. The end would do nothing.
Should frame manufacturer include all these filter recommendations for their own frame.
You would think they would but none do as far as I know.
dear sir..does it possible some in example 100Hz or lowering than 100Hz cut off in D-term can help us to run more cooler motor in others frames ...
is there any video to avoiding hot motors with the filter such as in firmware FalcoX instead of betaflight,,i guess it would be interest subject if someone like your background can give us from the side of your views between betaflight, kiss, Falcox, emu..or the worlds need new firmware or new brushless motor winding desain
@@zlachannel8674 increasing filtering will help with hot motors as will lowering your d gains.
@@SlipperyFPV ouh ok,,,i will try it,,,
@@zlachannel8674 good.luck... . remember to test hover for no more than a minute after any changes to check motor temps.
Yes, definitely. You can lower the D term cutoff but it will make performance worse. I wouldn't advise going below 70Hz.
2 dislikes. Maybe one from JB? 😁
I bet he has two accounts 🤣 JK. No he's been so nice about this analysis and even tried out my filter settings, what a man!
Hello Chris
i design my frame but im 13 so i dont now all about phisics and frame resonance so if you can help me i would appreciate
thank you in advance
Hi, I'm happy to hear you are thinking of designing your own frame. I am not able to help people individually at the moment but I hope you watch all my videos and they help you!
Nazgul5 V2 frame test?
I'm working on the iFlight XL5 frame at the moment, I think that's the one used on the Nazgul?
Any chance of doing this with the ummagawd 2fiddy
I've reached out to Ummagawd about this several times and got not response. If you send him a question maybe he will reply?
I've got some pretty good D, currently looking for a spotter 30~40yrs old... DM for D gains
Shame, its almost like they saw the 220hz resonance as a goal with this frame :( Design was obviously done before your videos ;)
The filter advice is just epic, so valuable as part of a frame review.
Thanks, I couldn't resist trying to help JBs frame fly even better!
@@ChrisRosser Great in dept analysis! I own this frame as well as I test out Ryans pre-protype frame, only for 7 inch though, where we get mostly a 300khz frequency filtered out.
Ahhhhhhh....my brain....ahhhhhhhhhh.
Don't worry! If you watch a few more of these analyses it'll make sense I promise!
I know the video is old but i have the same frame and i just cant tune it right. Ill be very happy if someone helps me with some pids and filters screenshot or something so i can finally enjoy my flights with this drone ;(
👍👀🇭🇷
AliExpress will contact you to get the cad files 😂🤣
My copies are already destroyed.
@@ChrisRosser 🙏🙏🙏
if u show a graph, please explain the graph first: ehat is x what is y axis
The graph is from betaflight blackbox explorer. If you are unfamiliar with this software there is a video series on it here: ruclips.net/video/VEALlGlcPbw/видео.html
It's a very useful tool for tuning quadcopters. I hope you find it useful!
Not in an apex. How do you mean every frame. Or is that just to excuse the frame for having resonance. What’s more important here. Your collaboration with bardwell or the facts. Aint no spikes on pex. None
Some builds with the Apex frame do have significant resonance peaks. And the Apex is quite a heavy frame (125g), it's easy to improve resonance performance if you make the frame 10% heavier. Not knocking the design of the Apex, it's a well thought out frame, just the facts.