Serious RTH firmware bug, are you seeing it?

[smiller]

I and one other P4P owner (so far) have noted an odd and potentially dangerous RTH behavior: Upon either a manually commanded or failsafe RTH the unit will climb continuously while enroute back to home point until it is either stopped by manually exiting RTH, or finally reaches its home point (at which point it will begin a vertical decent.) As far as we can tell the unit will ascend continuously until stopped, or at least we haven't experienced a limit. The pre-set RTH altitude setting seems to have no effect on this behavior.

This is obviously a serious bug since it could potentially cause loss of the aircraft and/or present a danger to other air traffic. The problem may not be noticed over short horizontal distances but over longer routes it is dramatic.

Can you all please see if you can duplicate this behavior? If it is happening on two units it is probably happening on more.

 

[Mark The Droner]

...The problem may not be noticed over short horizontal distances but over longer routes it is dramatic.

....

Can you give us an idea of how dramatic?

 

[Techcop50]

Sounds like one of the eggheads needs to dig into the log. Way above my pay grade...

 

[smiller]

About 500' undesired altitude gain over approx. 3500' (horizontal) in one case and about 920' undesired gain in another (not sure of the horizontal distance.) Even those gains are a potentially serious problem but what is worse it seems that the unit will climb without limit, other than a manual exit from RTH or reaching its home point.

 

[Mark The Droner]

Yeah that's dramatic!

 

[John Locke]

I and one other P4P owner (so far) have noted an odd and potentially dangerous RTH behavior: Upon either a manually commanded or failsafe RTH the unit will climb continuously until it is either stopped by manually exiting RTH, or reaching its home point (at which point it will begin a vertical decent.) As far as we can tell the unit will ascend continuously until stopped, or at least we haven't experienced a limit.

Regarding your statement " or reaching its home point" , I don't understand this. How can the craft automatically reach it's homepoint if it's only ascending? Are you saying the craft starts to return to home once it reaches the preset RTH altitude, but continues to ascend while moving horizontally toward home?

 

[smiller]

Regarding your statement " or reaching its home point" , I don't understand this. How can the craft automatically reach it's homepoint if it's only ascending? Are you saying the craft starts to return to home once it reaches the preset RTH altitude, but continues to ascend while moving horizontally toward home?

Yes, exactly. The unit's horizontal motion during RTH is normal, it's just that the altitude continuously increases enroute. Sorry if that wasn't clear and thanks for pointing it out, I have updated the OP to make it more clear.

 

[KevMo Photog]

Woah! That's not good!

 

[smiller]

No it is not. I'm hoping we can determine quickly if it is universal, but again, if it is happening on two units I expect it may be. If you are only flying out a few hundred feet you may not notice it, but as the horizontal distance grows it becomes very apparent.

 

[johnmont250]

i tested rth yesterday and this didnt happen, worked as it should, and very accurate.

 

[smiller]

i tested rth yesterday and this didnt happen, worked as it should, and very accurate.

What was the horizontal distance from where you initiated RTH to the home point?

 

[johnmont250]

What was the horizontal distance from where you initiated RTH to the home point?

about 1000 ft

 

[Glenn Goodlett]

I don't know if it is a bug, a setting, or we are not understanding what it is doing with respect to the settings.

Just did a flight and reset my units to imperial for easy comparisons. RTH altitude set at 130 feet. I tested RTH three times as follows;

1) I hit RTH at 500 feet away at 35 feet altitude. The craft climbed to 130 feet flew back to home at 130 feet and landed.
2) I hit RTH at 950 feet away at 80 feet altitude. The craft climbed to 130 feet flew back to home at 130 feet and landed.
3) I hit RTH at 2100 feet away at 80 feet altitude. The craft climbed to 130 feet, started back home but continued to climb to about 260 feet until about 1000 feet away then began descending until it hit 130 feet above the home point then landed.

EDIT- more data
4) I hit RTH at 5400 feet away at 100 feet altitude. The craft climbed to 130 feet, started back home but continued to climb to about 800 feet until about 2000 feet away then began descending until it hit 130 feet above the home point then landed.
5) I hit RTH at 5400 feet away at 100 feet altitude. The craft climbed to 130 feet, started back home but continued to climb to about 600 feet until about 1500 feet away then began descending until it hit 130 feet above the home point then landed. This time I had the RTH obstacle avoidance box unchecked. I had control of the camera tilt on the trip back to home.

 

[neven]

I don't know if it is a bug, a setting, or we are not understanding what it is doing with respect to the settings.

Just did a flight and reset my units to imperial for easy comparisons. RTH altitude set at 130 feet. I tested RTH three times as follows;

1) I hit RTH at 500 feet away at 35 feet altitude. The craft climbed to 130 feet flew back to home at 130 feet and landed.
2) I hit RTH at 950 feet away at 80 feet altitude. The craft climbed to 130 feet flew back to home at 130 feet and landed.
3) I hit RTH at 2100 feet away at 80 feet altitude. The craft climbed to 130 feet, started back home but continued to climb to about 260 feet until about 1000 feet away then began descending until it hit 130 feet above the home point then landed.

I don't know what is going.

Sounds like easily reproducible bug. Scary one. I wonder how much would it climb on battery RTH initiated 15.000ft away and would it even make it home.

Sent from my SHIELD Tablet K1 using PhantomPilots mobile app

 

[smiller]

I don't know if it is a bug, a setting, or we are not understanding what it is doing with respect to the settings.

Just did a flight and reset my units to imperial for easy comparisons. RTH altitude set at 130 feet. I tested RTH three times as follows;

1) I hit RTH at 500 feet away at 35 feet altitude. The craft climbed to 130 feet flew back to home at 130 feet and landed.
2) I hit RTH at 950 feet away at 80 feet altitude. The craft climbed to 130 feet flew back to home at 130 feet and landed.
3) I hit RTH at 2100 feet away at 80 feet altitude. The craft climbed to 130 feet, started back home but continued to climb to about 260 feet until about 1000 feet away then began descending until it hit 130 feet above the home point then landed.

Case 1 and 2 appear to be normal/expected behavior. Case 3 is not, the unit should not climb above preset RTH altitude unless there is some reason (encounters an obstacle, etc.)

I guess I can try an IMU calibration but the unit flies perfectly under other circumstances, i.e. very stable and flies flat and level when not in RTH mode. And the RTH return point is very accurate, the only glitch is the altitude anomaly. I guess we just need to wait and see whether this is just a few units or many.

 

[Glenn Goodlett]

I added a little more data to my previous post.

I would not do an IMU cal as others have had problems.

I don't think it is a bug but maybe we need to modify our ideas of normal/expected behavior. I'm guessing they all respond this way. Not sure if I like it or not.

 

[Rom3oDelta7]

Given this is way over the FAA ceiling due to no fault of the pilot, I would think DJI has to address it. @smiller, I assume you sent the logs to DJI support?

@Glenn Goodlett, curious why you don't think this is a bug. If the behavior varies based only on the horizontal distance, and it exceeds (by a lot) the max altitude setting, how can this be normal behavior? I definitely don't like it. As @neven noted, if this happens on a low-battery initiated RTH it could be disastrous.

Can you regain manual control when it starts to climb? Also, what happens if you cancel RTH when this occurs, and then re-initiate it? Weather permitting, I will try this myself later this week.

 

[Glenn Goodlett]

Just did two more tests seemingly identical to the previous and the craft did not climb and just returned at the set RTH altitude.

Maybe it is a bug. I don't know.

 

[smiller]

Given this is way over the FAA ceiling due to no fault of the pilot, I would think DJI has to address it. @smiller, I assume you sent the logs to DJI support?

I'm not certain how to do that, I can't access the .txt log for manual uploading because it is stored on a P4P+ display unit and I don't think I have direct access to the directory. I have synced my flight logs to DJI via the DJI GO app, I assume that uploads the logs automatically. There are also the large .DAT logs stored on the aircraft, not sure if that should be sent or how to send it.

 

[Glenn Goodlett]

Given this is way over the FAA ceiling due to no fault of the pilot, I would think DJI has to address it. @smiller, I assume you sent the logs to DJI support?

@Glenn Goodlett, curious why you don't think this is a bug. If the behavior varies based only on the horizontal distance, and it exceeds (by a lot) the max altitude setting, how can this be normal behavior? I definitely don't like it. As @neven noted, if this happens on a low-battery initiated RTH it could be disastrous.

Can you regain manual control when it starts to climb? Also, what happens if you cancel RTH when this occurs, and then re-initiate it? Weather permitting, I will try this myself later this week.

My max altitude is set at 500 meters so it never has gone above that. I could see gaining altitude as an advantage if signal is lost.

You can regain control anytime the aircraft is connected.