Hello.
Had a curious incident today. After around 4 minutes of flight copter started to noticeably wander. Feeling cautious i started to bring the bird back to me when suddenly i felt that it responds to sticks not the way i expect it to. Next thing, after releasing the sticks, it goes into increasing toilet-bowl. Luckily there was enough space to react: kill the gps (I really really hate that guy who stuck it so far into the menu) and bring the bird down unharmed.
After analyzing the telemetry i was surprised by some peculiar yaw values. But no compass errors were present (except those when raising / lowering landing gear). Neither did the controller alert me in any way.
In any case - bird had a dozen or more flight before without any bigger incidents. Yes, it sometimes had done some strange things like needing some roll compensation to fly straight (i attributed that to crosswind) or once it flew in slight diagonal during RTH (landed properly nose away from me though). But no such issue before with this bird (I had a similar incident though in the past with another H, when the compass went nuts twice in exactly the same place. Still unsure whether it was faulty module / calibration or some place-related anomaly, maybe because of a near-by transformer or hydro power plant. The bird was exchanged for reasons unrelated to that).
What was different from all previous times was the fact that i was flying in around 0'C temperature. So my question to the audience would be:
* Has anyone done numerous flights with H in near 0'C or slightly below temperatures. By that i mean in tens or more, not a few occasional flights. Did you experience any problems not occurring before which you would attribute to the outside temperature? Or have all flights been stable as usual?
* Does the temperature also affect IMU? Should i re-calibrate the compass when ambient temp drops / rises a certain number of degrees? The IMU warmup warning did came on and took a couple of seconds to clear. From that i so far had assumed that the low ambient temperature should not require any special treatment.
And yes, i do not exclude that the previous compass calibration i had done recently was poor. However the bird had a few short flights after that without any such issue. In fact during the same morning it was rock solid stable and landed practically with centimeter precision where i wanted it to. So this wasn't the first thing i thought about.
Telemetry attached for those who might take an interest in this.
Had a curious incident today. After around 4 minutes of flight copter started to noticeably wander. Feeling cautious i started to bring the bird back to me when suddenly i felt that it responds to sticks not the way i expect it to. Next thing, after releasing the sticks, it goes into increasing toilet-bowl. Luckily there was enough space to react: kill the gps (I really really hate that guy who stuck it so far into the menu) and bring the bird down unharmed.
After analyzing the telemetry i was surprised by some peculiar yaw values. But no compass errors were present (except those when raising / lowering landing gear). Neither did the controller alert me in any way.
In any case - bird had a dozen or more flight before without any bigger incidents. Yes, it sometimes had done some strange things like needing some roll compensation to fly straight (i attributed that to crosswind) or once it flew in slight diagonal during RTH (landed properly nose away from me though). But no such issue before with this bird (I had a similar incident though in the past with another H, when the compass went nuts twice in exactly the same place. Still unsure whether it was faulty module / calibration or some place-related anomaly, maybe because of a near-by transformer or hydro power plant. The bird was exchanged for reasons unrelated to that).
What was different from all previous times was the fact that i was flying in around 0'C temperature. So my question to the audience would be:
* Has anyone done numerous flights with H in near 0'C or slightly below temperatures. By that i mean in tens or more, not a few occasional flights. Did you experience any problems not occurring before which you would attribute to the outside temperature? Or have all flights been stable as usual?
* Does the temperature also affect IMU? Should i re-calibrate the compass when ambient temp drops / rises a certain number of degrees? The IMU warmup warning did came on and took a couple of seconds to clear. From that i so far had assumed that the low ambient temperature should not require any special treatment.
And yes, i do not exclude that the previous compass calibration i had done recently was poor. However the bird had a few short flights after that without any such issue. In fact during the same morning it was rock solid stable and landed practically with centimeter precision where i wanted it to. So this wasn't the first thing i thought about.
Telemetry attached for those who might take an interest in this.
It was meant to illustrate the difference in behaviour. Although i do like to think that optical flow helps somehow, because H drifts less during landings at daytime compared to landings in the dark.
