Hi,
I was flying in STABILISE mode and suddenly my drone climbed and rammed to the wall. Data log shows that there are inputs from controller but my throttle was Zero as soon as it started climbing and i had not given any inputs from my controller.
Please can someone verify and help me find what exactly has happened.
This same drone had flown with 3.5.5 code earlier and it was all good. Today i had loaded with 3.6.7 and did all COMPASS calibration, RC calibration. https://drive.google.com/drive/folders/1QSkbnIwGDYNHT24NnmEZcNSZYDvk6xtK
Can’t see anything obvious via an initial brief look except that all three IMUs show a change in the Y axis gyro before the craft lifts off which coincides with RCIN input.
It looks to me like the pilot gave it full throttle on takeoff - log shows it went from ground idle to full throttle in 1 second. It launched like a rocket. The pilot pulled the throttle to the bottom stop and all the motors went to idle. But by this time it was in a ballistic trajectory, still going up with the motors idling, and drifted into a ~60 deg right roll. The pilot held the throttle at the bottom stop for a little less than one second, then hammered on the throttle again which launched it directly into the wall, being in a quite unusual attitude after the rocket launch takeoff.
Unfortunately, to me, looks like pilot error and maybe a bit of wind could’ve been involved. It could not stabilize itself with all the motors at idle thrust while it was going up in a ballistic flight profile.
Thank you for the reply. Till 11% Pilot gave throttle still vehicle was on ground but after that it suddenly took off but my throttle stick was pulled to ZERO. There was no other inputs from pilot after that sudden takeoff like rocket. In data it shows inputs are from controller this keeps me worrying and there is 80 degree ROLL but my angle is limited to 45 degree
I graphed the RCIN from Channel 3, which is the controller throttle stick. The log shows that the pilot went to 100% throttle at takeoff, the aircraft rose rapidly, the pilot pulled the throttle to zero for about 1 second, then applied throttle again.
Outputs to the motors indicate they went to zero thrust when the pilot pulled the throttle down. But the drone had launched so rapidly it continued to rise with the motors just idling.
In the graph image above at line 19100 throttle and motors were at the bottom. But the only two lines that continue to go up is the altitude and the roll attitude drifting into right roll because the drone was unstabilized with all motors at idle thrust.
At line 19200 the pilot again applied throttle and the motors sped up. But it was in ~80 degree roll at that point and control was lost. Control was not regained before it hit the wall. The system did try to stabilize it again when the pilot re-applied throttle. But it was too late. The rapid launch threw it out of control.
Probably the RC is somehow strange configuered? A logarithmic throttle response curve?
Offtopic: I had a crash some weeks ago too. Some strange thing combined with GPS problems and a flyaway, fist in RTL and than in Loiter and Stabilize. I think there was some strange interference on the field.Are you having a general interest in looking into the logs in order to discover problems or are you doing this only for the pilots because you are a nice human?
I looked at it because I am concerned if something in the code could be wrong that caused a crash. In this case, I do not seen any indication that there is a problem in the code.
Hi,
Faced similar kind of issue with my quad today, where my quad took-off aggressively even though my RCIN was under the take-off limits, my setup is as follows,
T-Motor MN-501S 360kv
T-motor AIR 40A esc
Pixhawk 2.1, AC 3.6.7
AUW - 5.255 kg
I started flying in STABILIZE mode, from the data i could see that RCIN is 1280 pwm max, but RCOUT reached 1800+,
Need help, If anyone here could help me, link for the data flash log is added https://drive.google.com/open?id=1eM_45tuKcjw7n6so7r_JbMPzdfowFoWt
@YVKR Your quad is too overpowered/underweight
You do not have enough low end control
Try adding some weight
Could not tell how tuned or not from the short flight log
Vibes look ok
Your post would better seen if you created your own topic rather than pegging onto the end of someone else’s.
@mboland thanks for the analysis, sorry as I saw the thread I had posted, in future I’ll try not to repeat.
Okay, about the quad, it is not tuned yet, with the same motor setup I have flown on the same vehicle with less weight in the past but my propellers are the only change, earlier I have flown with 18" CF and now I have used 18" APC.
This time I actually added 800 grams payload as I was trying to replicate weight of another quad.
So any throttle parameter setup would have helped in smooth take-off?
Thanks in advance.
Have you read through the Wiki? Especially Autotune here.
As you can see, you have plenty of power headroom, but the floor is too close, so you can raise the arms well but not lower them, as the motors are visually shut down a lot already.
Sorry @mboland, I didn’t understand your question about Autotune, my intention is to d Autotune eventually after getting it to fly till ALT-HOLD.
Can you please explain me the RCIN and RCOUT parts of the flight as i understood that both are not matching in terms of thrust generated. and what could have caused the difference?
