Today I was flying my copter (GAUI 330/APM1/v.2.5.5 from MP) and suddenly it made a very strange flip/roll. Luckily I had some height and the copter stabilised after e few seconds but this was quite scary. Before and after this moment everything was as normal.
I had just taken off and was doing a fairly high speed forward flight agains the wind. It was quite windy (10-15 m/s).
If you look in the attached log, you'll see that at around lin 15740 there is a large spike in the roll value.
Can anyone comment on what might have caused this?
There has been a recent fix to the code for throttle management.
The fact was that the controller was giving full throttle leaving no space to manage stability.
This is in part (probably) what was happening to you, but there could be other reasons. Infact it never happened to me and other devs. Probably your setup is reaching it's limits in terms of weight, and/or wear.
Reading better your last post I understand you are using the OLD gaui 330x with black motors (and under rated 6A ESCS). This setup was well underpowered and had different issues concerning ESCs, often burning because of too high current needed by motors. This is why soon after the first 330x (that I currently own) the 330x-s with 10A ESCs and Scorpion motors was launched. If this is the case, you should consider changing ESCs or not to fly with high load and at maximum throttle.
@Alvin I doubt this problem is affecting you, yours seems more a configuration problem. Be sure you have entered correct value for tuning and that you don't have any strange values when you connect to the planner.
My setup has the 10 Amp ESC and Scorpion motors.
As for the fix, are you saying that it is best to revert to 2.5.3 and wait for 2.6? Or is it easy to patch the 2.5.5 code and fly with that?
@emile an Chris,
I reset my ESC's to default and all seems well now.
Which brings me to a point:
As the software currently is, the ESC calibration is initialized by powering up the copter twice with the full throttle engaged. As I understand it, basically the first power-up arms the ESC calibration, and the second one performs the actual calibration.
However it is quite easy to enter calibration mode without noticing something has happened, and I guess unintentionally entering program mode of the ESC's was the root cause of my problem.
This could be prevented by requiring an additional action at the first power-up. For example instead of just powering up with full throttle, also require full right yaw for >5 seconds before the calibration is armed and the slow sequential flashing of led's starts. This would greatly reduce the risc of accidentally changing ESC settings.
Would you agree this is a valid reason for an enhancement request?
wow! I had this exact same thing over the weekend. From my point of view, it went inverted, backwards.
I was in rather quick forward flight and came to a slow stop (backed off on the throttle, not harsh) and it seemed to over-cook the stopping process. The back fell "underneath" and the front came over the top. I froze, expecting it to tumble but in a panic I gave it a bit of throttle and it recovered itself. Flew around for a while longer without it happening again.
Had some aggressive flying before and never seen it do this.
I can submit my log tonight when I get home if that helps.
3DR quad X config, APM2 2.5.5, with sonar, 850Kv motors
@Gerrit I'm happy you solved your issue, although I still suspect there is something hardware related.
I recently had a friend witth a gaui x-s that had strange behaviours with yaw. It turned out it was the motors connectors were getting desoldered (they are really crap and too small IMHO).
Regarding throttle calibration I don't think your solution will be pratical because you have to connect the battery while you keep your sticks in a certain position.
A good practice is to alway check your radio before attaching the battery. A full throttle is quite visible. :)
And if it does not boot the first time, a suspect something is wrong should be your first thought.
@emile, I had some yaw issues too, so I soldered the ESC/motor wires, they are indeed quite fiddly.
About the extra arming step:
I think you misunderstood me what I'm proposing is only an additonal action for the first phase of ESC programming:
Now the procedure is: (from the wiki)
What I'm proposing is to add an action only to step two (changes in bold):
So after step 5 everything remains the same, and there is no holding of sticks while fiddling with batteries. The point is to never enter ESC calibration without positive user action.