Reading the vibrati...
 
Notifications
Clear all

Reading the vibration graph and values correctly

10 Posts
2 Users
0 Reactions
46 Views
 olli
(@olli)
Active Member Customer
Joined: 3 months ago
Posts: 6
Topic starter  

Hi there, I try to read and understand the vibration graph correctly, but when I compare the values and the graph to some older posts in this forum, I seem to not get it. Some are writing about vibrations on a level of 500, 199 or alike, but my graph doesn't have these numbers on the y-scale - max is 100 and below in x there is RPM, which I think is a mistake and should by Hz. However, I seem to only have very minor vibrations, never going above 100, but nevertheless, I'm not sure that I read it correctly and want to understand, before hitting rescue for the first test time 😉

 

Is there any documentation out there to dig deeper into this and understand correctly, what I'm reading there? After 12 years of Heli-flying, this is my first Brain, so brand new to this thing. 

Thanks for any hint!

Olli


   
Quote
(@customercare)
Reputable Member Admin Registered
Joined: 6 years ago
Posts: 1118
 

Can you send us the Recorded Log file, so that we can also see what you see?

https://www.msh-electronics.com/forum/general-discussions/if-you-are-asking-for-support/#post-2210

About RPM vs Hz, you can read here: https://www.msh-electronics.com/forum/postid/2896/

Thank you


   
ReplyQuote
 olli
(@olli)
Active Member Customer
Joined: 3 months ago
Posts: 6
Topic starter  

Thanks a lot for the links. Here's what I see (Unable to attach anything "No more attachments are allowed today"):

Graph Picture:

<a title="Vibration Graph" href=" removed link " target="_blank" rel="noopener"> removed link

 

Logfile:

removed link

 

Thanks,

Oliver


   
ReplyQuote
(@customercare)
Reputable Member Admin Registered
Joined: 6 years ago
Posts: 1118
 

Please, can you send the file in annex to a mail to "customercare@msh-electronics.com"?

Thanks


   
ReplyQuote
 olli
(@olli)
Active Member Customer
Joined: 3 months ago
Posts: 6
Topic starter  

Thanks, done.


   
ReplyQuote
(@customercare)
Reputable Member Admin Registered
Joined: 6 years ago
Posts: 1118
 

Thank you for sending us the recorded log.

From what we see relative to model vibrations, they seem to be on good values.

Global Vibrations are at 67% well below the maximum threshold of 200% (about one third).

Neither the problem of high vibrations at low frequencies nor the sea grass problem (vibrations of low amplitude but spread over the whole spectrum) is present.
This is of course if the log of these vibrations was obtained with the model in flight order (with the main and tail blades mounted at the rotor RPM values that are used in flight).

However, there is a problem in the settings of the "Pulses For Rotation", "Main Gear Ratio", and "Tail Gear Ratio" parameter values set in panel 12 of the Wizard.
In fact, the vibrations the actual RPMs, do not match the values calculated by the ECU based on the values of these three parameters (the thin vertical lines in the graph).
With the values currently set for these parameters, the governor of the ECU would not be able to operate properly at the RPMs set and required of the governor.

immagine

 

Also, at the main rotor RPM we see two different vibration values. Usually this is caused by incorrect blade tracking (so it seems that the log was made with the blades mounted).

However, not having sent us the configuration file, we are not able to know what is the size of the model (blade length) and whether it is with electric or combustion engine (Nitro, Gasser). However, if the model had combustion engine, the vibrations would definitely be higher and due to the explosions in the combustion chamber, clutch masses, exhaust pipe resonances, cooling fan, and starter shaft.

So we are going by intuition because, in addition to not sending us the configuration file, you have not even told us these basic things.


   
ReplyQuote
 olli
(@olli)
Active Member Customer
Joined: 3 months ago
Posts: 6
Topic starter  

Wow, thanks a lot for all this analyses! You are really great! I will now go and fly first, before bothering an further. I am flying a Kraken 580, Nova 4025-1120 and a HW 150 v5 on MS Composit Blades 580. I am not using the Brain‘s governor, but the HW‘s one, this I have not configured the gov and ratio etc in the Brain.

You think, I should and use the Brain gov?

 

currently on vacation and back tomorrow so I can provide the Config, if you want.

 

Thanks a lot for your help!

Best regards,

Olli


   
ReplyQuote
 olli
(@olli)
Active Member Customer
Joined: 3 months ago
Posts: 6
Topic starter  

Hi there, here's my config - as I wrote above, the Kraken 580 is configured with the following components: Nova 4025-1120 and a HW 150 v5 on MS Composit Blades 580 and Azure Power 105s on the tail. I am not using the Brain‘s governor, but the HW‘s one in Store mode, thus I have not configured the gov and ratio etc in the Brain. But now, after you wrote it - I entered the correct ratios for main and tail and put in the 4 for pulses of my 8p motor. But this corrected configuration does not reflect the flight log I sent you, as you have already pointed out. Thanks, Olli

Screenshot 2024 04 05 103126

 


   
ReplyQuote
(@customercare)
Reputable Member Admin Registered
Joined: 6 years ago
Posts: 1118
 

Posted by: @olli

.... But now, after you wrote it - I entered the correct ratios for main and tail and put in the 4 for pulses of my 8p motor.

Good,
You will now be able to:
- Display the vibration graphs correctly.
- Transmit via telemetry corrected RPM values.
- The safety features that activate when RPMs increase will work correctly.

In the title of Wizard panel 12, "Optional" is not indicated for the first section "Throttle Out" as it is for the later telemetry and governor sections.

By loading your configuration file in demo mode, we see that:
You have not done what is indicated for diagnostic purposes in this message that appears whenever you save a configuration file to send to us for diagnosis:

immagine

So we are unable to verify and tell you whether your transmitter configuration was done correctly by checking it in panel 5 of the Wizard.

In the first panel of the Wizard, for the cyclic and tail servos you have set "Unlisted". Can you tell us brand and model of the servos you are using so we can see if they are servos we have already added in the apps in development or if they will need to be added?

In panel 9 "Tail Setup" of the Wizard, the limit values still appear to be the default ones. Have you checked the maximum and minimum tail control excursions?

In ADVANCED, Common tab, Receiver section, we see that you have disabled the channel for controlling the three different Setups. Why did you do this since Radiomaster can control up to 16 radio channels? Aren't you interested in being able to set three different values for a parameter and being able to change the parameter in flight to see which of the three values the model performs best with? Or use three different gains when using different RPMs?

Also, we understand that your flight controller has been manufactured about eight years. Since we are curious, we wonder why until now in these eight years you never checked the vibration graph before and only ask for an explanation now.
Perhaps you purchased the flight controller second-hand and used?


   
ReplyQuote
 olli
(@olli)
Active Member Customer
Joined: 3 months ago
Posts: 6
Topic starter  

Hi there and once again, thanks for the thorough analysis and the very valuabel tips. I have done mostly everything now you pointed out:

 

1. I saved the configuration file again with the intended Analysis method of holding the sticks down right - hopefully correct this time. 

2. The unlisted servos are the GDW G50 and the GDW G95 for the tail. In my first setup with the Brain2, I also did not find any NexSpor servos, which are very likely to be found in the German community.

3. Tail setup - I have set the limits correctly now - don't know why I forgot this - thanks!!

4. Setup switch - yes I am not used to use different banks or setups - I always run everything from one setup and only have one speed for take off/land and the rest is done with the main headspeed - I do not fly aerobatics. I switch my gain with one of the trim switches (modified them to act as +1/-1 in EdgeTX) until the gain is balanced and the I set it based on a fix value. But I still have to understand P and I values and, although flying helis for more than 10 years, am still pretty new t the deeper ides of fine tuning.

5. And finally, yes, I bought it used and only have mounted and flown it once. But wow, this thing is 8 years old? Crazy, but that says a lot about the quality of your devices!!!

6. Now for the final and most difficult part and I have to say, I'm not a dummy - an electronics engineer of 50 years of age - but, no matter how often I read the throttle out stuff including internet research - I just don't understand it. First of all, I don't understand what it is for - what does it do and why do I need to set it? "...in order to match the units output to your TX" - okay, but why? It maybe that the throttle signal is not just passed through 1-to-1.

Finally, when I get to the instructions it says "drop the MIN endpoint to ensure....". I maybe a bit dumb here, but drop it to where? While it all is switch on and not armed, or armed already, but that does not make sense, because it only arms once. And then drop it one click by another to find the lowest value the systems still arms? Is this the goal? I use switches and flat linear "curves" to set the ESC output and not any stick. Now the text continues with "...then increase it slowly until the motor begins to spin..." do you mean increase the throttle or increase the Throttle Min value? And when I have found the value, what do I do with it. The second point is a bit clearer, but until I haven't figured out what to do exactly with the MIN value, I cannot proceed. Maybe I am really a little dense here 😉 because obviously so many people seem to understand it. I will try, but spooling my system up in my house to 100% in step 2 is something I don't like to do because of the noise and in the garden, I don't have my computer. Have to lok at the integration with my Radiomaster TX16s, which works fine, just to mention that.

 

And finally, please don't get me wrong, this is no complaint at all - I'm just having difficulties following the intended procedure. But I will eventually figure it out - always do 😉

Regardless of this, thanks so much for all your effort!

Best regards,

Oliver

 


   
ReplyQuote
Join Waitlist We will inform you when the product arrives in stock. Just leave your valid email address below.
Email Quantity We won't share your address with anybody else.