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?

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Jesse, your Z levels looks too high at least for 3.2.1 with that level you can't have good althold

OK, so here's progress so far.

1. Tricopter runs good on 3.2.1.

2. Quad is running 3.2. Board is vibrodampened and a bit stabilized with wight. Flies pretty OK, but it seems to me that AutoTune needs to be redone. Stops are very fuzzy, looks like D parameter is not enough. 

Loiter mode is good, AltHold is good.

Couldn't get BATT_VOLT2 working though, for no particular reason. It just don't work.

Well, I don't have the same options that you do in CTUN but I was able to use my GPS data and Baro data for ALT to get this graph.  I am assuming the lag with GPS is that it is not as direct to get the response from the SAT the ALT.. but my Alt Hold is 80% better now that I have removed some foam covering the baro and changed the vibration dampening.  I am running 3.1.5 too.


I am one of the few who reported early in this thread, when I downgraded from 3.2.1 to 3.1.5 it fixed my issue.  I am only able to upload the log file now, as I took a break to did some South Island New Zealand videos.  Then when I came back, unfortunately my APM powered H600 quadcopter had a crash.

Well now my H600 is repaired.  I then flew on 3.1.5, then upgraded to 3.2.1.  It seems I am not suffering from this issue.  I did a change a few components and also my H600 is about 200g lighter when it was on 3.2.1 before.  The arms are now longer but stiffer, I changed the double sided tape foam on the APM to be a double sided tape silicon.

I measured my vibration on 3.1.5 and 3.2.1, seems similar but maybe 3.2.1 is a little worse, but its within tolerance.  Here is graph where I flew indoors just hovering for a few mins.

Here is a log file of one of the flight

Log file

I am still new to log file analysis but here is a screen shot of CTUN -> DAlt, CTUN -> BarAlt, GPS -> RelAlt.  It seems to be ok now.

Here is another flight.

Log file

On about 4 minute, I went full forward pitch.  This made the quadcopter loose a bit of altitude as there is not enough thrust for lift.  My OSD goes nuts warning me of max vertical speed.  I then backed off and altitude is gained back.  It seems the barometer reads a sudden big gain up, while the GPS reading I believe is closer to what happened a bit of a dip and gain.  Is this normal?

I occasionally received similar false altitude values on 3.2.1 firmware as I mentioned at the beginning of this topic. It was a bit dangerous especially at a few meters above the ground. I made same frame improvements for lowering vibration level, tried a several foams, made many program changes, etc. but without any luck. Helped me to return to 3.1.5 firmware. Now I have hundreds flights without any dangerous glitch. I hope that developers will fix 3.2.1 in a near future. This latest firmware for APM have some new useful functions.

HI there,

When you downgraded to 3.1.5, did you have to retune your PID parameters? I attempted my first test flight today after downgrading and the copter just lost balance and fell over. It was as though the Stabilise and Pitch/Roll Rate P values were too low.

Yes, I did PID autotune and compass calibration. It is also a good idea to do factory reset after the firmware update.

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.


Guys, you can't just take and use everything is written in this topic thoughtless!

Analyze what is all about.

See, PILOT_ACCEL_Z changes only the way copter reacts PILOT input. It does not affect AUTO missions. In fact you are one lucky guy to get your drone back in one piece. 

The man who posted about setting PILOT_ACCEL_Z to 50 wrote that he is NOT using AUTO mode, so it was partial solution that fits for him, but not resolve issue. 

In fact, there should be some error in math concerning use of Z accel in altitude hold that can not be corrected with random settings change. To get reliable result you should be aware of what you're doing. 

I recommend:

1. Vibroisolate controller. In perfect case - redo all motors and prop balancing.

2. Flash 3.2 (in my case it's acceptable compromise between features of 3.2* version and stability of 3.1.5

3. Configure drone from scratch. Redo all calibrations, especially compass needs attention. 

Run autotune, and then fine tune PID's on fresh battery.

4. Make at least 5-10 successful flights in different weather conditions in manual mode before starting AUTO missions.


Personally, I just regig'd the Vibration System in my Thorax Mini.

Achieved vibration decrease by 40%

Successful AutoTune completed.

FineTuning Commencing weather permitting...

Sound advice....

Hi all,

Sorry, I am a little late to this party.

Is anybody having this problem with AC3.3rcX?

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