Litchi app crashed during waypoints mission

[danCER]

Greetings.
I have flown my Phantom 3 Standard on MANY successful Litchi missions and have had "lost signal" and "disconnected" warning but the Litchi app stayed open.
Today I went to fly a new mission and after a few minutes the Litchi app closed! I restarted it but wasn't certain if I opened the same mission what would happen.
I just barely could get signal back and initiate RTH--and I tried RTH a couple times before it "took."
Thankfully my drone returned safely--my worse heart attack yet!

So am I correct in assuming that if the Litchi app crashes during a mission that it will continue on the mission
even if you reopen the app? Or should I leave it closed and pray to the Drone Gods to guide it back safely?
I use a Nvidia Shield K1 which only has the Litchi app installed and not DJI Go as instructed by the Litchi team.

Any thoughts why the app closed? This is the first time that has happened.

 

[BourgeoisSJC]

The mission will continue with or without the app. Happened to me in the middle of the winter and in the dark. Scared the begeesus out of me In fact, didnt even occur to me to re-open the app. I think I was in shock The last point of the mission was right near where I stood so when it came back I just flipped the p1 switch on my P3S controller and landed it.

 

[solentlife]

Litchi - unlike Go - has the autonomous function of not needing the App once sent out on its mission.
As long as final point is close to home - there is all the reason you will bring her home fine.

Nigel

 

[danCER]

Thanks for both of your replies.
I contacted Litchi Support and they said if app crashes during mission just open Litchi app again and change to waypoint mode...that's it...don't reload mission...and it will continue on mission.

 

[danCER]

And I always have final waypoint back where I started for this very reason!

 

[SkyHog]

Thanks for both of your replies.
I contacted Litchi Support and they said if app crashes during mission just open Litchi app again and change to waypoint mode...that's it...don't reload mission...and it will continue on mission.

Yes, it will finish the mission, whether or not you restart the app. In fact, it will finish the mission, whether or not you have your RC is turned on. Once you launch the mission, the bird will fly all the waypoints as planned, even if you shut down your RC. However, you will need the app, plus RC, for any speed changes, gimbal pitch changes, and mission finish actions (e.g. land after last waypoint).

So it's a good practice is to always design your Litchi mission to end with a final waypoint directly over the home point, as others have said. I usually make two final waypoints; one to fly to home point at altitude sufficient to any clear trees and obstacles near homepoint, and then a final waypoint that causes descent to a fairly low altitude over the home point. If all else fails, and the dog runs away with your controller, the bird will just hover over home point at a low altitude and you might be able to grab it, or in the worst case, wait for the battery to run down to 10% so the bird will autoland from there anyway.

I've flown over a hundred Litchi missions, and I've only seen the Litchi app crash twice during a mission. In both cases, I simply restarted the app, and it just started reporting status of the same mission right where it left off, without any other action on my part, just as if it had never shut down.

 

[BourgeoisSJC]

However, you will need the app, plus RC, for any speed changes, gimbal pitch changes, and mission finish actions (e.g. land after last waypoint).

Something I have wondered about is that if I mess with the controls thereby overriding mission settings, what happens when I let go of the controls? For example, WP 9 in a mission is "focussed" on POI 4. I adjust the gimbal so the camera focuses elsewhere. What happens if I let go of the gimbal dial???

 

[Dan Lee]

I have a Litchi question I've been wondering about. If you send the bird on a long mission theoretically it will go as far as the battery will let it but would it not return to the home point once it gets to the failsafe battery level where it only has enough battery to get home like it does in the DJI Go App provided you have failsafe enabled?

 

[SkyHog]

Something I have wondered about is that if I mess with the controls thereby overriding mission settings, what happens when I let go of the controls? For example, WP 9 in a mission is "focussed" on POI 4. I adjust the gimbal so the camera focuses elsewhere. What happens if I let go of the gimbal dial???

You can execute control with the RC during waypoint missions (assuming you are in RC range), and the bird will respond to your commands, e.g. you can raise or lower the altitude. However, the Litchi mission will resume according to plan when it reaches the next waypoint, which will then overrides whatever you have changed.

Gimbal pitch control is a particular problem on Litchi long range missions, because the pitch remains fixed if you fly beyond RC range. So a good mission plan will anticipate that and set a universal static pitch (such as -15 degrees) before you get too far away, so that all the POIs beyond that point will still be in the field of view with that fixed pitch, and your waypoint distance and altitude may have to be adjusted accordingly. Yaw still works for POI focus, but not gimbal pitch, once you lose RC control signal.

 

[SkyHog]

I have a Litchi question I've been wondering about. If you send the bird on a long mission theoretically it will go as far as the battery will let it but would it not return to the home point once it gets to the failsafe battery level where it only has enough battery to get home like it does in the DJI Go App provided you have failsafe enabled?

Yes, it actually does return to home with Smart RTH, with the Litchi App. Smart RTH is set by the DJI Go app, but it persists in the bird indefinitely, even if you run the Litchi app a month later.

I've had a couple of instances where Smart RTH kicked in during a Litchi mission, when I had planned a particularly aggressive Litchi mission. I was disappointed the mission didn't complete, but thankful to have the bird back. Some have complained that the Smart RTH algorithm is too conservative. In one instance, I had the Smart RTH kick in when I had 63% battery remaining. However, the bird landed with just 30% battery remaining. Smart RTH was smart enough to see that I would need a lot of battery to just get back home, but not smart enough to wait just a bit longer before turning around. Some would prefer that Smart RTH kick in later and use another 20% of battery, but I'm not crazy about pushing things to the edge. Winds and battery performance are not always so predictable.

 

[Dan Lee]

Thanks for the info SkyHog. I have Litchie but I have not really used it except for just trying it out in an open field. I've been a little afraid to send it out on a long mission but I need to trust in the App and give it a try.

 

[SkyHog]

Thanks for the info SkyHog. I have Litchie but I have not really used it except for just trying it out in an open field. I've been a little afraid to send it out on a long mission but I need to trust in the App and give it a try.

I know the feeling. It's a good idea to plan and execute some simple missions first, to build confidence in the app, before launching longer missions. Your early tests in an open field are a very good idea.

 

[BourgeoisSJC]

Gimbal pitch control is a particular problem on Litchi long range missions, because the pitch remains fixed if you fly beyond RC range. .

I find that odd. I would have thought all required info for a given mission would have been uploaded at the start. Wonder why pitch requires the RC connected?? Then there is the question, what is connected?? I have flown lots of long/distant missions and only on very rare occasions do I get the "Signal Lost" message. The mission log file however, on most of my long missions will show plenty of zeros in the Uplink column. Next time I am out I am going to try to control the drone when on a mission at it appears I have no control signal but before the "Signal Lost" error.

 

[SkyHog]

I find that odd. I would have thought all required info for a given mission would have been uploaded at the start. Wonder why pitch requires the RC connected?? Then there is the question, what is connected?? I have flown lots of long/distant missions and only on very rare occasions do I get the "Signal Lost" message. The mission log file however, on most of my long missions will show plenty of zeros in the Uplink column. Next time I am out I am going to try to control the drone when on a mission at it appears I have no control signal but before the "Signal Lost" error.

The short answer is, Litchi has to work within DJI SDK limitations. Technically, the Phantom could have been designed another way, but it is what it is. Speed changes, Gimbal Pitch, and Finish Actions are all done within the Litchi app, through the RC link in real time with the bird. So they cease to function beyond RC range. The fundamental 3-D space navigation waypoints (position and elevation), are the only things that are uploaded to the bird at the start of the mission. Things like interpolated pitch for POI focus may require more memory or processing power than DJI wanted to allocate to the drone. I'm not sure why the finish action or waypoint speeds couldn't be preloaded. For whatever reason, the SDK does not allow any of that information to be preloaded at mission start.

In any case, if the link goes away, the complete set of waypoints will still be flown because all that information was uploaded at mission start. No links are needed to complete navigation through all waypoints. This opens up the range of the P3S tremendously, and is a great asset for those flyers that are otherwise disappointed with the P3S link range. But Litchi does require some attention to detail when planning missions, to be sure the bird flies home correctly.