P3 Standard - Litchi mission AC stopped & hovered for 2 mins

[Iain McC]

I was running a 13 minute mission yesterday and lost remote signal for 3 or 4 minutes. I was concerned that the drone had exceeded the time I would have expected it to have returned and, PRIOR to losing the video feed, it appeared to be stationary.

I switched to GPS mode and attempted to send the RTH command. No joy. I was actually walking back to my car to go and hunt for the drone when the remote started beeping, signifying that the drone was returning home. Phew! It returned safely and I have all the footage. It just stopped and hovered for 2 minutes.

I've checked and rechecked the way point settings and all seems to be in order. The drone was never far away from me.

Any thoughts or suggestions?

 

[With The Birds]

There are issues with the standard and litchi ATM with orbit, Fpv and other modes where you have control of the AC, specifically RTH will not activate on signal loss and the AC will autoland at critical battery. If you were flying LCMC the AC should have continued the mission to the last waypoint.

Is it possible you managed to exit the mission while you still had connection (just prior to signal loss when you switched to GPS mode )? This seems like a very plausible scenario. If you did RTH would not trigger, the AC would have been hovering and by some stroke of luck (intermittent poor connection) your RTH command was received with the AC returning as you were walking to the car. You got the returning to home notification when it was close enough to reconnect properly.

You may have been close but were far enough out not to have VLOS so a poor connection with a standard at this range is not uncommon.

Upload your log to healthydrones.com for some clues.

 

[Iain McC]

Thanks, all quite possible
I'm still a novice but I have successfully flown a few Litchi missions. As a novice, I like to fully concentrate on what is happening and, twice now, I have had passers by stop to chat out of curiosity. I am happy to chat but I do find this very distracting so, it is conceivable that, during the initial period of distraction, when the telemetry was lost, that I somehow managed to send the "Pause" command.

Not quite sure how I go about uploading my log but I'm sure I'll find something by googling it.

Many thanks!

 

[With The Birds]

Thanks, all quite possible
I'm still a novice but I have successfully flown a few Litchi missions. As a novice, I like to fully concentrate on what is happening and, twice now, I have had passers by stop to chat out of curiosity. I am happy to chat but I do find this very distracting so, it is conceivable that, during the initial period of distraction, when the telemetry was lost, that I somehow managed to send the "Pause" command.

Not quite sure how I go about uploading my log but I'm sure I'll find something by googling it.

Many thanks!

It's easy to upload Ian, are you in android or Apple? We can take you through it. Knowing what actually happened builds confidence and comfort going forward.

I think you may well have got concerned when you saw the glitch in the video feed and the switch to P mode halted the mission just as you lost signal or had very limited connectivity.

We all learn by doing ;-)

 

[Iain McC]

Ok thanks, I uploaded my log to healthydrones.com and, if I'm honest, I'm not a lot the wiser. It appears as if immediately after the signal was lost the mode changed to GPS Atti. This was before I became aware that the drone was hovering so pretty sure it had nothing to do with a remote input by me. Is it possible to upload the file here for an expert view?

Iain

 

[With The Birds]

Ok thanks, I uploaded my log to healthydrones.com and, if I'm honest, I'm not a lot the wiser. It appears as if immediately after the signal was lost the mode changed to GPS Atti. This was before I became aware that the drone was hovering so pretty sure it had nothing to do with a remote input by me. Is it possible to upload the file here for an expert view?

Iain

Yes, when you have the flight open click the green button top right of the screen, click create share unique link (bottom of page) and copy and paste the link here.

 

[Iain McC]

Ok thanks again.

Here it is:
HealthyDrones.com - Innovative flight data analysis that matters
Iain

 

[With The Birds]

Iain (beat the autocorrect and got your name right this time), the log file seems to confirm the suspicion as to what transpired on this flight.

4min 46 in you lost connection 500 m away, the AC continued to fly the mission as expected. At, or sometime before 8min 26 your AC is 800m away. You had a poor connection at this time, the AC did manage to receive the command when you flicked the switch to P mode though, effectively ending the waypoint mission. At this point the AC sat in a hover. The connection remained poor however it seems while returning to your car at 10min 38 while connection was established you managed to get a RTH command to the AC. AC happily flew home.

The reason this happened is that the current litchi app has n issue with the DJI firmware/Sdk where if you loose connection while flying the AC RTH will not kick in.

I will suggest a couple of things to you;

1. If your flying a waypoint mission and your last waypoint is close to home don't do anything if connection is lost. The AC will happily complete the mission.

2. Have a think about your altitude settings when planning a mission. I dont know the terrain however most of your programmed flight was reported as less than 5m above your home point (you may have been 100m above the actual ground for all I know its just a suggestion).

Happy flying!

 

[Iain McC]

Hi With The Birds, great feedback. I think you are spot on.

I had even considered the height potentially being an issue myself. It was deliberate as the mission was over water (the River Forth) and I wanted to experiment with how that looked, relatively low down. This would maybe affect the signal range.

I'll not let it put me off and have more confidence that the AC will complete the mission with no interruption from me.

I didn't mention before that I managed to crash the AC on a previous mission and I have some concerns that it is damaged internally. I have great difficulty getting the gimbal guard back on for transportation now and suspect it is slightly bent. Who knows what else is hurting inside. It was a Litchi Mission I set up and, at the last minute I "moved" the start and end points to a car park I was not expecting to be standing in. Sadly, the line between the penultimate way point and the new end point took the AC into a random high tree! I find trees and ACs don't mix well and lost a prop!. All part of the learning process I suppose.

Iain.

 

[Wessex]

The gimbal guard that comes with the P3S is a real pain to fit and remove. Look on Amazon for a lens cap with an extension arm that clips to the top base of the gimbal unit. It's a better idea than the original.

I also was a little concerned that the drone will not RTH if the signal is lost in FPV mode when using the LITCHI app. To stop and hover on the other side of a river say if the signal is lost means that the drone will hover until critical battery level is reached and then sink to the ground.

I suppose the answer is to use DJI GO or DJI ULTIMATE FLIGHT when flying manually.

 

[Drone_King]

I also was a little concerned that the drone will not RTH if the signal is lost in FPV mode when using the LITCHI app..

It returns home when signal is lost in FPV, just not waypoint mode (continues mission) or orbit (runs to critical battery, then lands).

 

[With The Birds]

It returns home when signal is lost in FPV, just not waypoint mode (continues mission) or orbit (runs to critical battery, then lands).

current as at 24 Nov 16 (litchi official position) "he following flight modes are affected: VR with Immersive/Joystick Head Tracking active, Follow, Focus and Track". Seems they must have fixed orbit.

 

[Wessex]

Thank you for the input DK & WTB. I since have tested the aircraft down to battery critical level in orbit mode and can confirm it will rise to RTH height and then descend.

Had issues with DJI Ultimate Flight and have since removed the app. I was having too many "SD card not found: Stopping Recording". It happened just before my aircraft crashed so I didn't see the point of impact. The aircraft fell around 60' and smashed the camera and will not now connect to the controller so suspect damaged transmitter/receiver in the aircraft.

Lesson learnt; bought new P3S but very careful how I set up automatous flights from now on.

 

[With The Birds]

Ok.... failsafe RTH not being initiated in orbit mode may mean that FPV might not work as expected either. You shouldn't be dirty on Litchi for these problems, it seems to be a DJI firmware issue. Wasn't that long ago autopilot would sit and hover until critical battery during a waypoint mission. Fixed with a DJI firmware release. I almost lost an AC over the ocean with that problem.

 

[Wessex]

Ok.... failsafe RTH not being initiated in orbit mode may mean that FPV might not work as expected either. You shouldn't be dirty on Litchi for these problems, it seems to be a DJI firmware issue. Wasn't that long ago autopilot would sit and hover until critical battery during a waypoint mission. Fixed with a DJI firmware release. I almost lost an AC over the ocean with that problem.

I am not getting dirty with Litchi, more like DJI Ultimate Flight which I have now uninstalled.
I keep DJI Go for configuring the aircraft but use Litchi first and foremost to fly.