AC3.2.1 APM 2.5 Throttle pulsates in Loiter

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?

Log.bin

Log_Vibration.bin

You need to be a member of diydrones to add comments!

Join diydrones

Email me when people reply –

Replies

  • I remember that on APM there was recommendation to add a Cap on one of the channels to reduce VCC spikes.

    Any recommendations or process on the Pixhawk ?

    • Hi Tsahi

      The power supply issues are supposed to be solved. However I notice the APM 2.7 has a 150uf filter cap. If you look in the log at VCC you see a lot of spikes. I have added a 2200uf 16volt cap across the 5.3 volt output in the APM power bec and covered it with heat shrink. I then looked in the log again and noticed a marked decrease of spikes so I believe its worth the effort.

      Cheers Henny

      • Hi Henny,

        do you know if its also possible / recommended on pixhawk as well ?

        • Thanks LTMNO for looking at my log. Been working on  vibrations just had a test flight

          and vibrations are better but AltHld still not good. This is my third build and never had this much problem. This frame looks like a TBS but is not TBS.    APM 2.6 (frame type set to V)

          810Kv 10x4.5 3 cell 3.2.1 FW PS: crash was just a tip over.

          2015-04-19 13-06-24.log

          • It will be pretty hard to get rid of vibrations with 810kV + 10x4.5 + 3 cell.

            I have 850kV motors + 4S and still rpm's are not high enough to keep vibrations in lower harmonics.

            How much does your copter weight?

            • @Marko

              Right now its about 4 Lb. I want to put gimbal and GoPro on board that will make it 4.5Lb.

              All my other build are 1000Kv with same 10x4.5 and 3 cell. You might be right ! I was looking at 11x4.7 props (my ESC are only good to 3 cell) I do need to set Mid_Thr up some more I have it at 550 now needs to go to 600. I might have to rethink this build.

              Thanks...............

              • Well, I got regular X with 850kV + 10x4.5 + 4s 3000mAh, loaded with gimbal + gopro2 + alexmos controller + separate camera and all telemtery + video stuff + separate FPV battery 800mAh. In total it's about 3.5 lbs.

                I think yours it a bit overweight for loadout. Maybe you should take a bit lighter battery?

                • I use a 3300ma battery. So you have the same problem as everyone else here?

                  If so have you been able to find a fix ? 

                  3.5lbs is very lite for that set up . The key must be 4 cell

                  • Well, partially.

                    I got rid of most vibrations, but still performance of copter it not as good as on 3.1.5 firmware.

                    There was clue described in this article here, but I haven't tested it yet.

                    On the other hand, on tricopter (5x3 2900kv 800mAh) I have no such awful drift problem. Yes, it can change height if you intend to leave it hanging for some time (like about minute), but basically it flies well. I can not test "loiter" mode on it because it has no GPS, but "AltHold" is pretty good. 

                    Key to good copter is in "coptercalc". ;)

                    Fixing the height drifting problem
                    On the third day of trying to work out why the UAV had issues with holding it’s height, we found a solution.  During research in to the problem my su…
  • Hello All, 

    after restoring the 3.1.5 firmware and setting the Throttle Accel to :
    3701983643?profile=originalAnd I slightly decrease the Stab R/P to 3.5 for my 330 Hex Thorax Frame.

    I am running APM Mini 2.7.2 with :

    2300KV Tiger Motors

    S12A ESC

    5x4.5 HQ Props

    External GPS/Compass


    Everything is Calibrated and within Parameters...

    Attached is Flight 1 with Default 3.1.5 Settings and the second Flight has modified Config as shown in picture above.

    The Hex looks as follows, 

    3701983660?profile=original

    This is my 7th, build and first time experiencing problems like this.  That being said, I have noticed some interesting results with Battery Readings... if someone has a moment to have a look, it would be greatly appreciated.

    Cheers!

    Flight_1.log

    Flight_2.log

This reply was deleted.

Activity