Very Disconcerting During Litchi Waypoint Mission

Have you tried changing the Mission Setting parameter from 'Straight Lines' to 'Curved Turns' ?
I started with curved turns. I changed it to straight lines to troubleshoot my heading problem.
 
Sometimes it works, sometimes it just ends mission, with the same mission?
Yes that is a tough one.

"The only thing is that the drone is not facing the POI like it should"
Facing horizontally?
Is it off a lot or just a few degrees?
If your up in the air, not a mission does the reporting heading look correctly?
Meaning close to you in your yard, point it at your garage, does it look like its pointing the same as displayed on the screen map / direction?
To me, that would be the clue for weather it needs a compass calibration.

Your talking about POI 1?

"I'm surprised there is no heading data in the litchi log file. Is it stored anywhere else?"
Your not looking at the instructions for the flight, you looking at the results of the flight, unless I'm missing something.


Rod
Rod,

Good questions. Let me address. Then I will follow up with a video.

It appears to be off by about 20 degrees to the left on the problem leg. Inside mission hub or litchi it shows heading of 108 degrees which looks correct. But when I check where is was actually pointing (by using landmarks on the video) it's about 88 degrees. Gimbal elevation looks correct.

It seems to be only at this POI (1) because a little later in the mission I focus it on a different POI (2) (house) and it looks OK. Furthermore, the heading starts out fine for the first leg. The problem only arises on the second leg.

I thought that because the suspect POI has a negative altitude (because its down the hill from where I took off) maybe its tickling an odd problem in Litchi. But that can't be. Apart from the fact that I would expect that to only affect gimbal angle (which is OK), The mission HAS the correct heading. It's just not pointing that way on one leg of the mission. I found a video on my mac from an earlier run of this and it looks like it doesn't have the problem. Yet the problem is reproducible now (unless the mission aborts). Maybe I should try a compass calibration for giggles even though it's fine elsewhere in the mission.

With respect to the heading comment..... yes I was hoping that the heading data recorded from the actual flight would be in the log - not the instructions. So I could see where it was aiming. But I used the video to extrapolate the heading by seeing where the camera was aiming at a certain waypoint. I used subtitles and VLC so it shows lat/lon on the screen. Then I used google earth to draw a line and see the heading.

I'll post the video when it's finished encoding.

Bill
 
Actually, on further inspection, the heading starts to go bad before the turn onto the second leg. But starts out OK for most of the first leg. here is the video with the first leg already in progress.

POI 1 is the building with the green roof. Heading and gimbal looks good for most of the first leg. Before the turn onto the second leg, Gimbal looks OK but heading moves left and stays about 20 degrees left till the next turn where focus is shifted to POI 2 (house on the top of the hill) and that heading is fine.

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You initially launched with 6 satellites, and at altitude you had 10 satellites. How hilly is the terrain in your area? GPS reception could be a contributor to your initial concern. Six satellites is the very minimum.
 
I had 11 satellites through the mission. Including the trouble spot. This is shown in the screen recording as well as the Litchi log CSV I pulled off the iPhone.
 

It gives me more of a visual of what the AC is doing. You would keep the same POI in each. There is a max distance in Litchi between waypoints but I don't think your close to that. I add more waypoints in some of my videos to make my turns be more smoother. I always use curved turns. You can change that turn in each waypoint make it small or large.
 
It gives me more of a visual of what the AC is doing. You would keep the same POI in each. There is a max distance in Litchi between waypoints but I don't think your close to that. I add more waypoints in some of my videos to make my turns be more smoother. I always use curved turns. You can change that turn in each waypoint make it small or large.
I don't understand how it gives more of a visual adding extra waypoints on a straight line? I understand about max distance and making curves smoother with more waypoints. Neither applies here. More waypoints on a straight line would also be needed if I were following terrain but I'm not. This is a small test mission to test something specific. These are actually fairly short legs compared to other longer and more complex missions I've programmed.

Also, I almost always use curved turns. My initial version of this had curved turns. I changed it to straight lines to test something.
 
I don't understand how it gives more of a visual adding extra waypoints on a straight line? I understand about max distance and making curves smoother with more waypoints. Neither applies here. More waypoints on a straight line would also be needed if I were following terrain but I'm not. This is a small test mission to test something specific. These are actually fairly short legs compared to other longer and more complex missions I've programmed.

Also, I almost always use curved turns. My initial version of this had curved turns. I changed it to straight lines to test something.


My apologies I forgot about it being "test something specific " mission.


But yes I use what the bird is doing on the PC screen as a visual of what the video will look like. I can picture it in my mind of what I want it to be. I guess I'm wired that way. And again I forgot it was a test mission.
 
You had said this same mission worked fine with POI 1 in the past?
So back on the compass calibration, doesn't seem like it would be a factor, since POI 2 works correctly.
I just watched the video two more times. :rolleyes:
Very odd it looks like the POI 1 drifted to the trees to the Left.

Rod
 
I know litchi aborts mission when sat locks drops before 6. I've noticed this when experimenting with flying under a bridge. (Side note: my P3P could maintain enough locks to fly mission while P4P would lose too many for Litchi's comfort and it would come to a hover using vision position hold).

Anyway lack of GPS at the point Litchi dumped out is not your issue, nor do you have any compass errors. Have you tried running similar waypoint mission with Go app or another app like Airnest, and see if it switches modes on you?

Unless there's something fundamentally flawed (like compass error and gps loss) you normally don't need to worry about your drone coming home if you have smart RTH turned on. It could hover out of sight and radio range but when battery depletes enough it will initiate RTH on its own. That function is independent of Litchi functioning correctly.
 
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I know litchi aborts mission when sat locks drops before 6. I've noticed this when experimenting with flying under a bridge. (Side note: my P3P could maintain enough locks to fly mission while P4P would lose too many for Litchi's comfort and it would come to a hover using vision position hold).

Anyway lack of GPS at the point Litchi dumped out is not your issue, nor do you have any compass errors. Have you tried running similar waypoint mission with Go app or another app like Airnest, and see if it switches modes on you?

Unless there's something fundamentally flawed (like compass error and gps loss) you normally don't need to worry about your drone coming home if you have smart RTH turned on. It could hover out of sight and radio range but when battery depletes enough it will initiate RTH on its own. That function is independent of Litchi functioning correctly.
Good point on the low batt RTH. Thank you. Feeling dumb that slipped my mind. Of course in a headwind it could still be a nail biter. :)
 
I re-ran the mission today three times after calibrating the compass. First of all, there were no unwanted Atti mode changes and mission aborts. Secondly, the aiming is much better. During the second leg where it was off by 20° before it's SPOT ON. Oddly enough now it's slightly to the right on the first leg. But I presume we can't expect total accuracy. So it's probably within the margin of error. I'm going to link to the straight lines run of the mission here. I'll link to a split screen version of two curved turns mission in another post to show just how reproducible these missions are. When it aims a little to the right, it does it "reliably." ;-)

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Here is something interesting. I'm attaching a collage showing my healthy drones track from two days ago (when I was having problems but eventually got a couple good runs) and today when I had no problems.

IMG_5224.JPG
 
Here are two separate runs of the curved turns version of the mission. Pretty amazing how exact they both are. If you know how to relax your eyes and do a stereogram you can watch in 3D :)

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Unless there's something fundamentally flawed (like compass error and gps loss) you normally don't need to worry about your drone coming home if you have smart RTH turned on. It could hover out of sight and radio range but when battery depletes enough it will initiate RTH on its own. That function is independent of Litchi functioning correctly.
Is it? I'm curious regarding the difference between interactive mode and flying a mission disconnected.

Even if you have RTH enabled, the aircraft will continue the mission to completion when disconnection rather than initiate a failsafe RTH. So obviously RTH can be overridden by Litchi under some circumstances. The question is, how is low-battery RTH affected by this? Thata "failsafe" RTH mode too.

I'm hoping you know with some evidence (the Litchi folks, DJI, official docs you read, experts you've spoken to, etc.). If it's just that it makes sense, I agree -- but engineers do make mistakes when designing complex systems.
 
Here is something interesting. I'm attaching a collage showing my healthy drones track from two days ago (when I was having problems but eventually got a couple good runs) and today when I had no problems.

View attachment 79239
My money's on GPS issues, which is consistent with all the evidence.

Remember, you can have more than enough sats locked in and still have very poor accuracy -- and therefore big errors -- when the geometry of the satellites is bad (extreme angles, for example).

This leads to your position wandering all over the place each reading. You very well may have just hit a particular configuration of satellites that were that once-in-a-while crappy geometry.

Something was making the logic conclude it did not have accurate enough location information to stay in P mode.
 
Is it? I'm curious regarding the difference between interactive mode and flying a mission disconnected.

Even if you have RTH enabled, the aircraft will continue the mission to completion when disconnection rather than initiate a failsafe RTH. So obviously RTH can be overridden by Litchi under some circumstances. The question is, how is low-battery RTH affected by this? Thata "failsafe" RTH mode too.

I'm hoping you know with some evidence (the Litchi folks, DJI, official docs you read, experts you've spoken to, etc.). If it's just that it makes sense, I agree -- but engineers do make mistakes when designing complex systems.
If Skyboysteve was answering my scenario then we are talking about the AC stopping the mission and hovering out there beyond range sitting in F-GPS mode (no longer F-WP mode). True that it's not in P-GPS mode either. But it's no longer flying a mission. But I suppose maybe it does need to be tested in order to be sure.

I'm guessing this could be simulated by flipping from F to A and back to F. Let the battery run down and see if it comes back. Doing this in an open field with the AC nearby.
 
My money's on GPS issues, which is consistent with all the evidence.

Remember, you can have more than enough sats locked in and still have very poor accuracy -- and therefore big errors -- when the geometry of the satellites is bad (extreme angles, for example).

This leads to your position wandering all over the place each reading. You very well may have just hit a particular configuration of satellites that were that once-in-a-while crappy geometry.

Something was making the logic conclude it did not have accurate enough location information to stay in P mode.
Interesting theory. Thanks. Too bad the logs don't contain DOP
 

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