DJI WKM Flip on motor start up, any ideas

[jhardway]

Looking to see if any one have any ideas, I was flight my copter for a few minutes doing a gimbal test when I landed it to adjust the camera setting. When I stepped back to restart the copter m2 motor cranked up and totally flipped the copter.

I am puzzled only because I have been flying the copter with no problem, but for something as simple as landing it and then on start up to have such a problem ????? :dread:, is there any one out there who has had the same problem? if so what do you think would cause such a thing.

I am wondering while adjusting the camera setting if my leaning over the gps att, if that would cause to have a problem and then get its orientation out of whack?

I had one of the first s800 when I had one of there mysterious crashes, DJI replaced the frame and flight controller but the crash happened in an area where my GPS signal was right on the edge of 5 satellites I feel the crash happened right in that grey area range. Today I am wondering my leaning over the copter putting the gps signal in the range could have caused that issue?

I look forward in hearing back for your thoughts.

Here's is a vid with sound from the on board camera.

i just put the vid up so it may take a few minutes to process.

thanks Jack

 

[ProPilotWannaBe]

Ouch! Sorry about that dude. I don't have answers for ya, but just a few questions that might help others as they think about it.
- I'm guessing you were taking off in GPS mode based on what you are stating. Is that correct?
- Was the WKM LED indicating GPS lock?
- Did you remove power between your initial flight and your second takeoff? Or did power remain applied to the WKM during the adjustments?
- How much time does the WKM have in this setup? Is it a new setup? Or something you've been flying for a while?
I personally can't imagine that disrupting the GPS signal momentarily would cause this, but then again, you never know.

 

[jhardway]

Ya not sure myself, I just landed the copter, did not unplug the copter power, I just changed a setting on the camera, then stepped back and started the motors by my sticks, in the vid it sounds like the m2 starts and goes full speed before the other even get a chance to spin.

When landing I did have lock on GPS, before starting the motors again the LED showed lock,

I did not remove the power I had it plugged in the whole time. I never touch the copter, just the camera on the gimbal.

I have done over 200 flights with the WKM, I did change it over to this new copter however it was a hexa to hexa so I did not have to do any changes with the setup, Since changing I have about 15 - 20 flight with it, and it has flown great the whole time. I did calibrate compass when I did the first flight.

I am not sure but I am wondering about the GPS when it goes in and out of full lock, but now looking over the video I am wondering when landing is it possible the landing could have of set the gyros and then cause the result. With that said should I have unplugged the copter just to have it re inquire its general orientation.

cheers

 

[ProPilotWannaBe]

So you are saying the flip occurred even before you applied the throttle for takeoff? You just armed the MR by doing the CSZc and it flipped? Am I understanding correctly?

 

[Benjamin Kenobi]

It's not your GPS lock. When it loses lock it just goes to ATTI mode. If every time you lose GPS lock it goes crazy I'm pretty sure NO ONE would fly again.

It's something else so start looking. The manual says don't let it idle on the ground for too long and don't start slowly. Quick start and in the air is mentioned. Weird considering the natural tendency is too go slow. How's the ESC on that motor? Did you calibrate the tx on the assistant?

 

[jhardway]

Benjamin

thanks looking at your signature info I believe you remember back just under a year ago when they recalled the GPS to be replaced with the new V2 versions. At the time they were experiencing such flips as what happened a few days ago.

over all who knows what it is, but here's one of my theories its just a theroy, I was one of those guys who had a s800 that did the flip of death, as they where know for at the time. There was not a ton of them but there was enough to spur a WKM GPS recall and for DJI to immediately ok a replacement 800 for me, no questions asked. The fact that is took over 3 months was not cool and the number of email I sent out to try to help in speeding it up did not matter.

when my 800 crashed the WKM was 11 month old, and like my recent flip the motor went into full throttle mode (m5) flipped the copter and crashed it. DJI's gps recall explanation for it was there was an issue in the Units firmware and they needed to be replace, at the time they urged people not to fly the copters until they had a new unit, That took 2 month (not cool again).

In both of my cases with my flips I believe my GPS signal strength could have been in the transitional area of having differential lock (or no red lights), in both cases I had a motor scream to full throttle and flip the copter, in both case the motor closest to north was the motor that freaked out (the north may be a coincident) and both copters were hexa configurations. I also believe in both cases that I had solid GPS lock; both times the copter was in an area where it may have degraded the signal to a point where it was on the edge of solid lock.

My first incident occurred when I was flying between two buildings where GPS could be hard to get at times. The most recent one, I was leaning over the copter's gps to adjust my camera setting while not unplugging the units so the GPS was live and me blocking the sky could have degraded the units signal. result ended up being the same.

On top of that I have had a dozen cases where I lifted the copter off the ground not it solid GPS mode and if I let the copter hover with little or no stick control, right as the GPS gets a solid lock I have seen it make a quick steep twitch in a direction to get to a position. Usually in these cases, as this would take place I would then correct the movement with the stick just by reaction and everything was fine. The first few times this happened it kinda freaked me out but over the time Its something I have grown to expect.

What I say here is just a theory and the basis of my thought only comes from incidents I have had over the last almost two years with these units.

Either way the results are frustrating causing me to have questions about trusting the electronics, and at the end of the day costing me $$$ and anxiety.

 

[Electro 2]

Was that "change on the camera" turning on WiFi backhaul ???

 

[jhardway]

funny, no it was just changing the camera's internal stabilization from active to standard to see what difference it would make in vibration. Who knew that could happen, unfortunately I saw some vibration, most noticeably when the ground hit the upside down copter.

 

[Benjamin Kenobi]

I saw some vibration, most noticeably when the ground hit the upside down copter.

Classic!

 

[Electro 2]

Dunno on WKM, but with MW, an immidiate flip on climb-out is a bad gyro cal. Holding the machine absolutely still during boot fixes it.

 

[gtranquilla]

Indeed.... when the ground comes up and hits me in the face........ I know I have had too much to drink!!!!!!!

funny, no it was just changing the camera's internal stabilization from active to standard to see what difference it would make in vibration. Who knew that could happen, unfortunately I saw some vibration, most noticeably when the ground hit the upside down copter.

 

[sim_io]

The motors aren't armed or even on idle so that means the WKM didn't intentionally tell that motor to fire up. A glitch in the firmware is my guess, I've seen nastly official firmwares that actually made m7 and m8 spooled up.