Hiccups during flights

In my last 2 flights I have some kind of hiccup 1-2 times. The 8kg octa flies very well after tuning (autotuning first, then redusing Stab P from 8 to 4).

First flight this day, at the end of the flight the octa made aggressive left/right movements. I think I can see sange behavior in the log line number 108,6 parameter ATT / DesRoll and Roll.

Link to logfile (~8.3MB, too large for forum attachments): drive.google.com/file/d/0B-nTtv … sp=sharing

Last trip the octa did “full” pwr 1/2 second in STAB mode. I think it was at line number 101,5 in the attached log. The only stange parameter I can see is GPS / VZ but I dont know what this parameter is.

Link to logfile (~7.5MB, too large for forum attachments): drive.google.com/file/d/0B-nTtv … sp=sharing

Anyway, I dont understand the hiccups…

(I can upload BIN files too if nescessary)

And here are the BIN files:

-hiccups in XY plane
-estimated at line number 108,6
[attachment=1]5 - flight #1 hiccups XYplane.BIN[/attachment]

-hiccups in Z plane
-estimated at line number 101,5
[attachment=0]6 - flight #2 hiccups Zplane.BIN[/attachment]

Regarding the first log, it seems to me that the twitch was caused by a drop out on the RCIN signals. Every single channel seems to go to 0 for a short period of time just when you saw the strange behavior. It could have been caused by the transmitter or the receiver or the ppm-summer (in case you use one). I’m no developer so I can’t say if this might be software related. But to see this drop out on every single channel is quite odd.

On the second log at around 101,5 the RCIN Chan3 (Throttle) goes from around 1500 to 1700 and the copter seems to follow that command. So I do not really see anything strange here, sorry.


Thanks! I can see what you are pointing at. Im using Graupner SUMO signal to the Pixhawk so if PPM sum reciever is the reason, then it is the Pixhawk unit that is something wrong with.

Based on what evidence precisely?

Because the ppm sum reciever is inside the pixhawk. But of cause, i dont know if ppm reciever is the reason here.

One thing a want to try is to shield the ppm cable between the rx and pixhawk. In case some noise doing the ppm signal corrupt. Is that a smart thing to do, anyone? :slight_smile: