Dangerous behave of CC3D
« on: October 05, 2016, 10:14:02 pm »
Hi,

Open this video: https://goo.gl/photos/yoQSBiFnKMqkema78

In the timeline go to 15 seconds, which is when I turn of the motors. If you see the next seconds (till the end of the video) randomly some of the motors spins and stop in a really strange way.

I am using CC3D and thi problem only happens with CC3D. With NAZE32 I have no problems, and I also use arducopter and no problems at all. This strange problem only happens with CC3D.

I think this is really dangerous cause even after I stop the motors (throttle to OFF) they dont stop, and someone walking close to it could get hurt.

In the case above I didnt disarm the quadcopter, I just reduced the throttle to off cause if I disarm it this problem does not happen anymore.

f5soh

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Re: Dangerous behave of CC3D
« Reply #1 on: October 05, 2016, 11:33:26 pm »
Please share your full config.

Help menu > Export UAV Data

mr_w

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Re: Dangerous behave of CC3D
« Reply #2 on: October 06, 2016, 12:09:49 am »
In addition to the config, can you give some insight into your receiver setup, and details on the timing of the input pwm/ppm fed to the cc3d.

What I suspect (but can't confirm without config and pwm timing info) is that your "turn off" throttle level is just at what you configured as neutral level for Throttle channel. This is most certainly not desired, as low throttle (off) should be few 10ths of uS below whatever is configured to be neutral.


Re: Dangerous behave of CC3D
« Reply #3 on: October 06, 2016, 02:33:44 am »
Thank you all for helping into this. I attached the exported file as requested.

My minimal throttle is at 1000us and neutral at 1200us. When I mean I turned "off" the motor I mean that the flightcontroller is receiving 1000us (minimal throttle).

I really hope someone can help me into this cause I had a flight a few minutes ago and the motors kept spinning randomly for almost 2 minutes before I could get close to the quad and pull the power off.

Re: Dangerous behave of CC3D
« Reply #4 on: October 06, 2016, 03:07:22 am »
FINALLY I FOUND OTHER PEOPLE WITH THE SAME PROBLE

https://www.reddit.com/r/Multicopter/comments/3gmtl8/never_had_this_happen_before_why_would_one_motor/

This guy has the same problem as me!!! But his solution has nothing to do with my problem, another guy in that thread says it could be a GND problem. Anyone else has experienced this?

What is the ARMING TIMEOUT
« Reply #5 on: October 06, 2016, 03:19:04 am »
Hi,

In my LIBRE PILOT software there is a configuration under INPUT - > ARMING SETTINGS -> ARMING TIMEOUT which defaults to 30 seconds.

What is the meaning of this? I thought it would be this: if I keep my throttle at minium (after arming my quad) for more than 30 seconds it would disarm automatically. But this never happens. So what is this configuration?

f5soh

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Re: Dangerous behave of CC3D
« Reply #6 on: October 06, 2016, 07:29:30 am »
Found two issues:

- Calibrate the inputs using the "Start Manual calibration" button
- Calibrate your Escs

All the motors do not stop when you put the Throttle to min and should stop because you are not using the "Spin while armed option".
So your issue is not only the front motors but all motors.

Re: Dangerous behave of CC3D
« Reply #7 on: October 06, 2016, 03:53:04 pm »
My calibration is ok: the receiver and ESCs are very well calibrated, they are precise and even though this problem still happens.

I didnt understand what you said "Spin while armed option". In my case this option is unchecked in the OUTPUT configuration of librepilot, so why checking this would solve my problem?

Also, any of you know what is the meaning of ARMING TIMEOUT?

mr_w

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Re: Dangerous behave of CC3D
« Reply #8 on: October 06, 2016, 04:29:00 pm »
Arming Timeout - if your throttle is zero (actually below neutral) and vehicle is armed, when this timeout expires, LP will automatically disarm.

Brian

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Re: Dangerous behave of CC3D
« Reply #9 on: October 06, 2016, 05:14:22 pm »
Do you have a logic analyzer?  Have you looked closely at your "receiver" outputs?  All the symptoms you describe could happen if there were glitches in your PWM signals.  The fact that it didn't disarm after 2 minutes of throttle off tells me that it's likely throttle jumped above the minimum threshold somewhere in those 2 minutes.  This could also cause the motors to continue to spin.


Re: Dangerous behave of CC3D
« Reply #10 on: October 06, 2016, 07:25:38 pm »
@Brian thank you so much. @mr_w thank you too.

I think my receiver is working fine but unfortunatelly I dont have a logic analyzer. Is there someway in the LibrePilot software that I can log all the PWM values my FC is receiving in all of it's channel? In the INPUT (inside Configuration) I can see the current value cause the "sliders" move when I turn on my transmitter.

Indeed my FC never disarms, never even with timeout of 5 seconds. I wait, wait, wait... and it never disarms.

I agree with you that maybe my receiver is not sending precise values to my FC, however this wouldnt explain why only one motor spins randomly for a few seconds, then another, then another...

I was wondering: when my throttle is 1000 (below neutral) and the drone is not disarmed, maybe some integral component of PID is making motor spin (cause P and D should not affect my drone when throttle is minimal).

f5soh

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Re: Dangerous behave of CC3D
« Reply #11 on: October 06, 2016, 09:07:58 pm »
If the board do not disarm after timeout when Throttle is at minimum you are not really at minimum.

Do a manual calibration and you should get others numbers.

Re: is there throttle curve setting in the librepilot app?
« Reply #12 on: October 06, 2016, 10:34:13 pm »
I did the calibration again but I am not sure if FC is receiving data correctly. Isnt there a place or button inside LIBREPILOT where I can easily see all values received by the FC in each one of its channels?

f5soh

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Re: Dangerous behave of CC3D
« Reply #13 on: October 06, 2016, 11:37:47 pm »
Post ^^ moved into the right thread ?

For input values, take a look at System tab > UAVBrowser

Data > ManualControlCommand > Channel

mr_w

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Re: Dangerous behave of CC3D
« Reply #14 on: October 07, 2016, 12:03:38 am »
batata003, keep in mind that PWM input has refresh rate of at least 50Hz so you would need to be able to see the changes 50 times per second. Your eye is (probably) not fast enough for you to notice if one of those 50 pulses in a second are too long (which can happen if your receiver does not use hardware to generate PWM signal). You would need logic analyzer to log at least couple of seconds, and then look for glitches. On the other hand, CC3D is fast enough to process all of those 50 pulses every second and if even one of them is longer then neutral, it will be considered as such.