I'm having an issue that happens periodically where for no apparent reason, my quad (tarot ironman 650) falls from the sky. Since my last drop, I'm now running with a brand new APM and 4S battery. I've attached the log from this latest drop and crash hoping someone can interpret and point me in the right direction. I'm beginning to wonder it relatively cold weather (approx. 20F degrees) impacts either the APM or the ESCs because this never happened before it started getting colder. Any input would be appreciated.
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It looks like the throttle input went to zero (red line). The roll then went out of control due to no throttle (green line) causing the quad to roll over despite corrective stick inputs (blue line). Based on the video's audio, it sounds like all four motors cut out at the same time. While falling a split second later, the motors make noise again which is consistent with the brief near full throttle spike that occurred after the quad was inverted.
While the throttle was at 0, other rc inputs were still being read successfully so I think the rc receiver maintained functionality the entire time.
I also dont think this was caused by an esc problem because that would show up on the throttle output side. Plus the motors appeared to work fine during the short throttle pulse right before crashdown.
Is it possible that you accidentally bumped the throttle stick to 0? Maybe the wire connecting the receiver throttle channel to the apm input became loose?
I really appreciate the input and analysis on this. That makes a lot of sense. I know I didn't bump the throttle to 0 so it seems logical that the connection from receiver to APM may be the problem. I'm going to actually replace all 4 cables from the receiver to the APM with brand new ones. Ironically, I just purchased a dozen servo cables last week. I was also thinking about replacing my receiver a couple weeks ago to rule that out since it's a relatively cheap item to replace versus the cost of repairs in the event of another crash.
There is still a chance that your cables and connections are OK. We isolated the problem to the input signal but there are still quite a few plausible explanations of what happened including an internal problem with the receiver that only impacted one channel, a problem with the APM reading the signal, a problem with your transmitter stick, and plenty more. I would take it easy and fly low for a bit after you get everything going again to make sure whatever mods you make solve the issue.
it would help to know the C rating of the battery, the size motors , AUW, milliamp capacity of the battery, whose esc and rating and firmware, prop size and pitch,what kind of power distribution board if any and brand. then at least some of the logs might make sense, I am planning on starting an tarot ironman 650 build with pixhawk so I was interested in your crashes. What kind of power distribution board if any and brand.
please let me know
HZL
gforce 25c 6000mah 4s
Tiger MT-3506-25 650kv
Afro 30A ESC (not using linear BECs)
Castle 10A switching BEC
12x4.5 CF props
HK Quadcopter Power Distribution Board (3.5 bullets)
In the video just right before the crash I can see the leds on the frame flashing red.
Is this the low voltage alarm?
Yea I saw that too. I'm using a JD-IOboard and those are the default flashing sequences on the channel it's hooked up to (I think it's left and right). I'll double check to make sure they are not coming from mavlink but I know they flash all the time and I haven't had time to figure out how to change them to be solid. I'm supposed to get flashing sequences for the flight mode on the rear channel of the IO-Board (I have LEDs on back of quad for that), and according to the documentation, the rear channel of the board is the only one used for reporting mavlink messages.
Forgot I had the actual video from the flight if that helps at all:
https://www.youtube.com/watch?v=rEU_NOE4zKs