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
I put a genuine 3DR APM 2.5.2, that was collecting dust, into my Quanum Nova to replace the factory APM that was in it. (The factory stuff requires custom versions of copter) The Loiter/AltHold pulsating started as soon as I upgraded to 3.2.1. After reading this info I started thinking the filter frequency could be my problem. Changed it to 20 and voila - no pulsing and a much better atlhold all around. Thanks to everyone here for this info.
Andy Piper said:
Mine was vibrations and some tunning. Solve it.
Elvin:after tunning you need to solve vibrations, don't think that only being under limits, you are ok with vibes, the pixhawk add more vibrations measure I hope for this problem Leonard can clarificate better; I finally changed my hole copter trying component by component that produce vibration including the APM for a Pixhawk but, in case, tired, I mounted on a tower of isolation systems (not recommended but works for me) I have this http://www.hobbyking.com/hobbyking/store/__76727__APM_Flight_Contro... and over there, the pads on the four corners that come with the controller, better idea is become with less isolation and add more if you need or change them and test until your copter performed well, I have the two extreme, my other copter, the controller is hard fixed, no isolation and performs nice,
If you migrate to Pixhawk you can enjoy the better last firms, if you have little space take in consideration Pixracer, the new board for little setups; Z values is common that are higher than x and y ones; if you don't solved with moon gel try with leonards orange foam under the corners or with this http://www.hobbyking.com/hobbyking/store/__76727__APM_Flight_Contro...
A thing that you can do easy, is to put aprox 50 grs weight over your controller well fixed with double sided tape until you recive the other dampening systems. (remember the compass if you use metalic material.)
Try autotune first and them you can do fine tunning, http://diydrones.com/forum/topics/ac-3-1-autotune-support-discussio...
This looks like the classic vibration issue. It looks like it is just ok in stabilize but as soon as you put a PID loop around the accel it blows up.
You may get away with dropping your Thr_Accel_P and I by 50% but vibrations are the cause of the problem. You can add vibration isolation or fix it at the source.
Hi Elvin,
What I am saying is the additional accelerations caused by Alt Hold are just enough to mess up the inertial prediction of height and climb rate. It is close to the breaking point before and Alt Hold pushes it over the edge.
Vibration dampening can be a fussy thing to get right, especially on the APM. Make sure there is nothing flopping around that could hit on the frame. Make sure wires connected to the APM are secured and won't flop around too much but leave enough length so they aren't tight. Make sure all screws are tight and your battery is secured hard against the frame.
The best vibration isolation I have found is the latex foam sold by Hobby King with some thin double sided tape (I use carpet tape). I use squares approximately 12mm on the side. This can tear during a crash so make sure you check it if you crash hard.
http://www.hobbyking.com/hobbyking/store/__26457__Anti_Vibration_fo...
If you have the gimbal installed during autotune make sure it is powered. If you find the tune isn't good then try without the gimbal.
Hi all,
Sorry, I am a little late to this party.
Is anybody having this problem with AC3.3rcX?
Hi Leonard - I think you'll find no-one on this thread can try 3.3 as they are all on APM.
3.2.1 DJI450 APM 2.6 810Kv 10x4.5 3 cell
After making changes to PILOT_ACCEL_Z FROM 250 TO 50 and INS_MPU6K_filter = 20
AltHld is better. Today I ran Auto Mission with ROI had Alt set to 15 lost Alt on the way to first waypoint
and never regain it very low maybe 25 ft ? Had RTL set at last waypoint then it did go up and return.
2015-05-10 08-20-40.log
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