Hi.
I have a problem after updating AC to 3.2.1 from 3.1.5.
When in Loiter, the the speed of the motors rev up and down/pulsate quite rapidly. This was working fine when I was using previous versions of arducopter.
I have downloaded the logs, and have looked into accX, accY and accZ. These seems to be inside the range specified in the wiki at arducopter. (Log_vibrations.bin)
Please have a look at the Log.bin, and note the difference between ThrIn and ThrOut when I'm in Loiter mode.
Anyone having any idea what the problem may be?
Replies
The second image is from the first log, on the last one accy value wasn't registered to check
Hi Cala,
Thanks for your input & help. I thought maybe it could be a vibration issue, so in order to test that idea out I replaced motors with brand new ones and re-balanced props. The logs I posted are with the new motors.
My issue here is that my vibration levels are the same as they were when I first built this ship; it used to fly FLAWLESSLY before the firmware update. It's very hard to understand why a version change could have this effect.. and if something did change in the code, it would be nice to know what that may be. These 250 quads running 2300kv motors are going to have higher vibes than the normal 450 size and up.. it's just the nature of them to have high frequency vibrations.
Some people here have good results returning to 3.1.5; I had a false positive issue with land on that vers but I flyed a lot this summer with it, Randy wrote in his post that next vers is going to be less sensitive to vibs but only for Pixhawk but if they find an issue in this vers they can fix it ( http://diydrones.com/forum/topics/arducopter-3-2-1-beta-testing?xg_... )
I copy here:
Reply by Randy on Wednesday
Marko,
I think Rob Lefebvre can help look into the specific issues some users are having with AC3.2.1 on the thread opened for that issue. We went through months and months of testing including many APM2 users but if it turns out to be a firmware issue that can be fixed we can release a 3.2.2.
I think it's usefull for developers if you try the two vers and post the two logs flying in similar conditions and solve the problem only changing vers.
When I had the issue, during calm days no problem and less vibs but in windy days it was near unflyable and vibs goes up. Now I have that cuad in changing process, waiting props and ext compass but I can reduce vibrations in windy cond and reduce pulsations a lot but don't mantain altitude as well as the other, perhaps very big props for that setup. I'm going to try with canopy as Hubertus suggest after changing props
Raph: in your last log vibrations levels looks bad, specially acc Z affects baro and try to climb
What you can do:
Check your motor props balance
Try fixing your controller directly with doble sided tape
Control your motor mounts, arms etc.
Looks here for more ideas http://diydrones.com/forum/topics/vibration-isolation-and-dampening...
A question regarding Throttle Accel P&I tuning: The wiki says:
"These values should never be increased but for very powerful copters you may get better response by reducing both by 50% (i.e P to 0.5, I to 1.0)."
In my case (powerful 310mm Quad) these values are yet at the bottom of the "Climb Sensitivity" slider (P=0.5/I=1.0). But as I have the known throttle pulsing in AltHold mode and the Quad loses hight very significantly during pitch and roll commands I am wondering if I should rise these values despite of the wiki instructions. I am a little bit worried to try it...
Experiencing similar issues after upgrading to 3.2.1,
First noticed on autonomous mission there would be a pause on flight legs where the discrepancy in altitude was outside permissible range, flight would pause(hover), then continue on.
Next day, took the rig out to do an autotune, which then created a pulsing action in AltHold and in Loiter, and flight is Stabilize was ok. Did multiple tweaks to PID's to smooth out the pulsing to no avail.
The Z axis vibration values appeared to be high, thus removed the foam shipped with the Pixhawk and used the Kyosho Z8006 gel. The vibration values did decrease some, and still getting the pulsing action in AltHold and Loiter.
May roll back to 3.1.5 if not able to remove the pulsing.
Cheers!
Have attached a Youtube video link for your info
https://www.youtube.com/watch?v=EQ3sGc2wJgQ
The ATC parameters should have nothing to do with the altitude hold issue.
The ATC parameters are used to "soften" the response of the system *only* to pilot inputs. The issue is that after a successful Rate PID tuning, using either Autotune or manual methods, the quadcopter can be too sensitive to stick inputs on Pitch Roll and Yaw. It is very "sharp" and reacts very strongly.
In the past, people used to turn down the Rate PIDS to make it softer, but this also makes it less stable relative to wind gusts, etc. ATC allows you to make the quad soft to your inputs, while also being stable relative external forces.
So ,what's the different between ATC parameters and RC_FEEL_RP??
I see them quite differently. The PID,s setup is about how the flight controller responds to its sensors and puts the appropriate feedback to achieve stable flight, the size of the machine also plays a roll because a large machine needs more input compared to a small machine. The ATC values appears to control how quickly a flight change from the guy holding the RC transmitter is acted upon. With the values in the 3.2.1 download made my machine feel light an aircraft carrier, response was very slow but only in stabilize or throttle hold. In Loiter it was fine, not sure why this happened but probably because my inputs in Loiter where processed thru the Auto Pilot and the ATC values were not needed.
Keep up the good work, I have learnt a lot in the last couple of months myself.
Cheers
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