Zero AGL rollover... what happened?

[Zzz]

I was landing my Solo after a nice uneventful flight in calm winds. I had just finished shooting some test footage from my new 8mm Edmunds Optics lens...more on that later.

I landed manually, as I like to do. It was one to be proud of, pax could have slept through it...until...explosion on the launchpad. Normally I kill the motors by burying the left stick down and... shit was it to the right? In a moment of muscle memory, I buried both sticks down and inside, like I do to kill the motors on my Mavic Air.

The Solo rolled onto its back and sat there grinding its props into the asphalt. In the end, I'm not sure what finally caused the motors to stop. Hopefully they aren't smoked.

So, what caused this? It was the end of a normal flight, so obviously not the props-on-the-wrong-pod issue that's a favorite for zero AGL rollovers. I was under the impression that the software wouldn't allow roll input if it knew it was on the ground, but that seems like a pretty tight window of accuracy for GPS given that i was maneuvering just inches above ground while landing.

But then... if the throttle is full back too...

Reading back over the Solo manual, the Emergency Procedure for stopping the motors is A+B+Pause. Why was I under the impression that throttle down and right was as motor kill input too? I flew this unit for a year+ before getting a DJI product. About half my landings are full manual, and that is how I killed the motors. Is it possible they were shutting off anyway after a timeout, and my input was tantamount to a placebo?

The manual also says the emergency motor shutoff is a last resort. Does that mean the only way to stop motors after landing manually is to wait?

Anyway, mostly unscathed. I ordered more OEM props. I've found them to be smoother than MA.

 

[Jodypaul88]

Lol I had this happen to me twice. Same as you my other drene I learned on and flew for 2 year's needed both joysticks down to disengage the motors, 3dr is just the left joystick down in tell motors stop.

 

[Jodypaul88]

Lol I had this happen to me twice. Same as you my other drene I learned on and flew for 2 year's needed both joysticks down to disengage the motors, 3dr is just the left joystick down in tell motors stop.

After lerning this and using just the left joystick, I never had this happen again.

 

[IrishmanPDX]

GPS has nothing to do with altitude. It receives longitude and latitude information only. Your barometer inside the pixhawk is measuring the air pressure outside and using that to gauge the altitude. If you descend too fast or if there's pressure variations cause by temperature variations, that's going to affect solo knowing what altitude it's at. So it's possible you're landing, you got 3 ft to go, but Solo's measurements are saying "5 ft to go". Now updated autopilot features help with autolands, it reduces the rate at which the solo descends and therefore gives the internal barometer time to "Catch up" if you will. Hence it slows down right before landing and crawls to a slow land. Even if the height is off, the slower rate means once it detects that it's staying still (not descending any further), it will automatically shut off the engines. However as you can guess, this isn't a fool proof system and this is why many people choose to land in "manual" mode.

In your case, you landed in manual therefore bypassing some of the "autoland safety features" and the drone did not detect it had hit the ground. You then added stick "inputs" which most likely caused the drone to think you were still flying it. You moved both sticks down and inwards, so that would make the drone want to "roll" left while descending, and given enough thrust it just flopped over on it's back. It's odd that the motor's didn't cut when it was inverted, but then again, it was probably trying to "right" itself because as far as it was concerned, it was still flying.

When landing in manual, do it slow, and when your drone lands, keep the throttle all the way down and to the left until the motors cut off. Do not land the drone and release the throttle before the engines cut as this could cause the drone to launch again, or roll over. I'm thinking your landing would have been fine if not for the stick input from your right hand which is what caused the drone to want to "roll". Hoping the drone is ok, I'd use the motor test in Solex to spin up one motor at a time (props off) to check for damage.

 

[Zzz]

GPS has nothing to do with altitude. It receives longitude and latitude information only. Your barometer inside the pixhawk is measuring the air pressure outside and using that to gauge the altitude.

Ahh, that makes sense. Barometric altimeters are much more sensitive. TIL... I thought it was using GPS altitude this whole time, which is indeed spotty.

When landing in manual, do it slow, and when your drone lands, keep the throttle all the way down and to the left until the motors cut off. Do not land the drone and release the throttle before the engines cut as this could cause the drone to launch again, or roll over. I'm thinking your landing would have been fine if not for the stick input from your right hand which is what caused the drone to want to "roll". Hoping the drone is ok, I'd use the motor test in Solex to spin up one motor at a time (props off) to check for damage.

My landing was quite slow and smooth compared to auto-land. I wonder, is there an inertial spike when it lands a little harder that triggers the "landed" status?

I took it for a flight today, motors perform fine. I did not know about the motor test in Solex though, thanks for the heads up. Is it okay to spin up motors without the prop on? This is a no-no with aircraft piston engines.

 

[IrishmanPDX]

My landing was quite slow and smooth compared to auto-land. I wonder, is there an inertial spike when it lands a little harder that triggers the "landed" status?
I took it for a flight today, motors perform fine. I did not know about the motor test in Solex though, thanks for the heads up. Is it okay to spin up motors without the prop on? This is a no-no with aircraft piston engines.

It may detect the "bounce" and use it as a secondary verification, but in this case, because you were in manual and you held your right stock down and in, this cause the flip over. Glad to hear the motors are ok though. Yes, it's ok to spin the motors up without props, in fact it's the preferred way to test the motors (as opposed to having props on and having your drone flip over again). The biggest no no of all is powering on the drone with a gimbal attached and no camera in the gimbal.

 

[Zzz]

It may detect the "bounce" and use it as a secondary verification, but in this case, because you were in manual and you held your right stock down and in, this cause the flip over. Glad to hear the motors are ok though. Yes, it's ok to spin the motors up without props, in fact it's the preferred way to test the motors (as opposed to having props on and having your drone flip over again). The biggest no no of all is powering on the drone with a gimbal attached and no camera in the gimbal.

I was not in Fly Manual mode, actually. I just opted to not initiate the auto landing using the FLY button. So, question: Does the Fly Manual mode somehow disengage all GPS-based autopilot position holding? I've only used it to pop up and get more satellites on my densely forested street, at which point I switch to regular FLY mode for better drift correction.

 

[IrishmanPDX]

I was not in Fly Manual mode, actually. I just opted to not initiate the auto landing using the FLY button. So, question: Does the Fly Manual mode somehow disengage all GPS-based autopilot position holding? I've only used it to pop up and get more satellites on my densely forested street, at which point I switch to regular FLY mode for better drift correction.

My mistake, when you said " I landed manually" I took that to mean you landed in manual mode.

Yes, Manual Mode "alt hold" disables the GPS position hold and only leaves the "altitude hold" mode engaged. So your drone will drift with the wind, you also need to correct for any inputs you make, so if you drift the drone left, it will keep going left until you apply sufficient counter thrust to stop or correct the drift.

 

[USMC86]

The silver lining to your trying experience-
a couple new sets of Master Airscrew Props!!! Order two sets ( come in a set of 4 ) and in four fabulous colors!! Black, White,
Orange and Green!! Order two sets and take advantage of the free shipping!!! They are quieter than 3DR stock props!!

 

[XevetS]

I was not in Fly Manual mode, actually. I just opted to not initiate the auto landing using the FLY button. So, question: Does the Fly Manual mode somehow disengage all GPS-based autopilot position holding?

When you are in fly mode and land manually yes it still utilizes GPS, you should of pulled the left stick straight down only although you can position the Solo with the right stick, If you had switched to manual mode it does not utilize GPS and you still use the left stick to throttle back and disarm by either pulling it straight down or down and to the left. To arm in manual its down and right. In manual mode the Solo will drift with the wind so you have to counteract with the sticks..Practice flying and landing in manual mode it makes you a better pilot and will be handy not if but when you lose GPS while in the Air..It'll save you a lot of Pain...

 

[Zzz]

The silver lining to your trying experience-
a couple new sets of Master Airscrew Props!!! Order two sets ( come in a set of 4 ) and in four fabulous colors!! Black, White,
Orange and Green!! Order two sets and take advantage of the free shipping!!! They are quieter than 3DR stock props!!

I've tried MA props and I found them to impart more vibration to the video than the OEM. I thought...what's the deal, everyone raves about these? I then bought a prop balancer and tried my hand at balancing. The results were still not as good as the OEM, perhaps due to my incompetence with balancing.

Anyone else have to balance their MA props?

I've used moongel, haven't swapped the HDMI ribbon though. But all things being equal, the OEM props made for smoother video than MA. Did I get a bad batch?

 

[Zzz]

When you are in fly mode and land manually yes it still utilizes GPS, you should of pulled the left stick straight down only although you can position the Solo with the right stick, If you had switched to manual mode it does not utilize GPS and you still use the left stick to throttle back and disarm by either pulling it straight down or down and to the left. To arm in manual its down and right. In manual mode the Solo will drift with the wind so you have to counteract with the sticks..Practice flying and landing in manual mode it makes you a better pilot and will be handy not if but when you lose GPS while in the Air..It'll save you a lot of Pain...

I flew helicopters before ever getting a drone, so I feel (IMO) that my manual landing game is rather on-point. This was 100% a case of both sticks down and inside to kill the motors, which is a DJI thing (oops, been flying my Mavic Air too much lately.) The bird reacted to those inputs while firmly planted on the ground and flipped over. My actual question was: Should it have?

 

[XevetS]

I flew helicopters before ever getting a drone, so I feel (IMO) that my manual landing game is rather on-point.

Did these helicopters utilize Ardupilot? Those stick gestures are the proper way to arm/disarm the Solo believe me...So yes from you pulling sticks down and in you told the Solo to flip over....

Arming the motors — Copter documentation

 

[BigTulsa]

I've tried MA props and I found them to impart more vibration to the video than the OEM. I thought...what's the deal, everyone raves about these? I then bought a prop balancer and tried my hand at balancing. The results were still not as good as the OEM, perhaps due to my incompetence with balancing.

Anyone else have to balance their MA props?

I've used moongel, haven't swapped the HDMI ribbon though. But all things being equal, the OEM props made for smoother video than MA. Did I get a bad batch?

Not me. I have four sets of MA props (2 black, one green, one orange) and they all work great. No video vibration whatsoever.

 

[Zzz]

Did these helicopters utilize Ardupilot? Those stick gestures are the proper way to arm/disarm the Solo believe me...So yes from you pulling sticks down and in you told the Solo to flip over....

Arming the motors — Copter documentation

Practice flying and landing in manual mode it makes you a better pilot and will be handy not if but when you lose GPS while in the Air

No. However you seemed to be under the impression that my flying was the issue and that flying and landing manually could somehow prepare me to not flip it on the ground after landing while trying to disarm the motors. I stated that I've flown helicopters with success to demonstrate that I'm not new to manual RC rotor flight. I still have much to learn about the more automated types though.

Given the popularity of other products on the market, I can't be alone in making this mistake (both sticks down and inward).

 

[XevetS]

Not me. I have four sets of MA props (2 black, one green, one orange) and they all work great. No video vibration whatsoever.

I Like the MA props myself, seem more aggressive but the stock Solo props seem to offer smother video it could just be an imbalance on my MA props not sure though but they are far from a bad prop...

 

[XevetS]

No. However you seemed to be under the impression that my flying was the issue and that flying and landing manually could somehow prepare me to not flip it on the ground after landing while trying to disarm the motors.

Given the popularity of other products on the market, I can't be alone in making this mistake.

Nope that was not what I meant You posted that you were in "Fly Mode landing manually" I posted that landing in Manual is the way to go, this way you have total control and will not have a GPS/Multipath issue while landing in Fly mode that's all I meant...I assumed you were a noob at flying...My bad..

 

[XevetS]

Given the popularity of other products on the market, I can't be alone in making this mistake.

We have all flipped the Solo upon landing, The newest update Fixes that issue 1.5.4 as a matter of fact or OpenSolo 1.5.4 Or If you are running a GreenCube APM 3.5.4

 

[XevetS]

Do you think it's worth a feature request to the guys working on Ardupilot or Opensolo? (preventing this stick combo from flipping it after landing.)

See my above post what firmware are you running?

 

[Zzz]

We have all flipped the Solo upon landing, The newest update Fixes that issue 1.5.4 as a matter of fact or OpenSolo 1.5.4 Or If you are running a GreenCube APM 3.5.4

haha...getting out of sequence.

So, the newest firmware actually prevents that stick combo from behaving as if it's flying? how does it determine "landed" status?

See my above post what firmware are you running?

I'm running stock firmware, on Arducopter 1.5.3 I think. I did make one firmware update since buying.