Question:

Flied by "Waypoint" on P3P / Android Litchi 3.10.5. When the connection
is lost, "Return to Home" is activated. In the early versions of Litchi,
the drone carried out the mission to the end.
Now it should be like this?

https://healthydrones.com/main?f ... de476dc155a05ca0050

Answer from Litchi:

This is not the RTH triggered on signal loss.
When signal is lost, the drone will continue the mission always. If you see a RTH soon after, it is caused by the DJI firmware that decides to RTH early because it thinks it won't be able to complete the mission and return home safely.

Kind Regards,
Litchi

Why does the drone not continue the mission?

I have had a similar experience. Like you, I have always had Litchi continue the mission. Up until recently. I have one place I fly that is around a factory that I like to get some video of. I have flown this many time before and never had a RTH with Litchi. A month ago I purchased a new tablet, a Nvidia shield to replace one I was already using.....I gave that one to my son. Anyway, not exactly sure when I did the latest firmware upgrade, but when I got my new tablet up and going  and I run this mission around this particular factory, it gets all the way to about the farthest point which is about 2-miles, and Litchi says "Aircraft requesting to go home". It triggers the RTH and I cannot do anything to resume the mission. I have tried even running it backwards, same RTH. I doesn't do it on any other mission except this particular one, which really has me stumped. I wondered if it was some signal the factory might be giving off that interferes with the phantom? But here is another twist. I decided in an effort to figure this out to run the mission on my Galaxy 5S........and it runs perfectly without the RTH triggered. Can't figure this out. To me it points to the tablet, but I have used it one a number of other missions where I know I am going to lose the signal, and it never has failed me, always running the mission complete. I also wondered if it is a combination of the new Litchi version along with my new Shield? The shield is running the same OS as my old one V6.0 Marshmallow. The old Shield never triggered the RTH on this mission around the factory. Wish I had an answer. What is triggering the RTH is what I don't understand.

I wanted to add this, I have a strong signal the entire mission. That is what I don't understand. I don not have any lose of signal....but the RTH gets initiated.

I also see that you have a strong GPS signal your entire flight. I looked at mine too, and the same applies to my flight.

I did some investigating on this RTH with Litchi. I also contacted Litchi and kind of got the same answer as you did. From a few other forums and some digging around, it seems that DJI have embedded into the firmware this "Smart" RTH feature. It is in the Go app if you look. A lot of misconception about how it actually works. But most agree, that if it is toggled "ON" in the Go app, it is like some of the other features such as "EXP, GAIN, and a couple other things" it writes this information to your aircraft, and it is stored there. The "Smart" RTH monitors the battery and determines how far away you are and will force the phantom to abort your Litchi waypoint mission, or any other type flight whether it be Litchi or Go app. If you turn it "Off", it does not disable the normal RTH for low battery or signal loss. In my situation I explained earlier when I tried the missiont with my Galaxy S5, I didn't realize the I had this option turned "Off" in the Go app. I re-ran the previous flight I was experiencing the RTH with a Litchi mission, same tablet, etc., but turned "Off" the smart RTH in the Go app before I switched to Litchi.......worked perfectly like it was intended. Don't know if this will help anyone else, but it was the "FIX" for me. The particular flight I had issues with is one of my longest ones, around 5-miles total distance, but the phantom must think it is a bit too far for it to make it back home, but I make it back every time with at least 30% battery left. I'm leaving it turned off in the Go app.  

It wasn't really an issue, but was the only time I experienced the RTH with Litchi mission. More of a challenge to figure out I guess. I have used the Litchi mission to go some places that left me without a signal for 10 minutes , and it always returns with amazing footage. I do take the time to investigate the flight path, altitude, etc. But it allows me to go around corners, over bluffs and such that I would for sure lose signal and have a RTH without using Litchi. It is a very powerful tool as far as I am concerned. The first few times you do this though is very tough on the nerves. seems like an eternity waiting for it to return! But at this point I have done it enough that I have full confidence it will come home. Happy flying.

RicardoGray Posted at 2017-3-14 04:09
I did some investigating on this RTH with Litchi. I also contacted Litchi and kind of got the same answer as you did. From a few other forums and some digging around, it seems that DJI have embedded into the firmware this "Smart" RTH feature. It is in the Go app if you look. A lot of misconception about how it actually works. But most agree, that if it is toggled "ON" in the Go app, it is like some of the other features such as "EXP, GAIN, and a couple other things" it writes this information to your aircraft, and it is stored there. The "Smart" RTH monitors the battery and determines how far away you are and will force the phantom to abort your Litchi waypoint mission, or any other type flight whether it be Litchi or Go app. If you turn it "Off", it does not disable the normal RTH for low battery or signal loss. In my situation I explained earlier when I tried the missiont with my Galaxy S5, I didn't realize the I had this option turned "Off" in the Go app. I re-ran the previous flight I was experiencing the RTH with a Litchi mission, same tablet, etc., but turned "Off" the smart RTH in the Go app before I switched to Litchi.......worked perfectly like it was intended. Don't know if this will help anyone else, but it was the "FIX" for me. The particular flight I had issues with is one of my longest ones, around 5-miles total distance, but the phantom must think it is a bit too far for it to make it back home, but I make it back every time with at least 30% battery left. I'm leaving it turned off in the Go app.  

It wasn't really an issue, but was the only time I experienced the RTH with Litchi mission. More of a challenge to figure out I guess. I have used the Litchi mission to go some places that left me without a signal for 10 minutes , and it always returns with amazing footage. I do take the time to investigate the flight path, altitude, etc. But it allows me to go around corners, over bluffs and such that I would for sure lose signal and have a RTH without using Litchi. It is a very powerful tool as far as I am concerned. The first few times you do this though is very tough on the nerves. seems like an eternity waiting for it to return! But at this point I have done it enough that I have full confidence it will come home. Happy flying.

Thank You, RicardoGray!

I have found Lichi to have a lot of "known bugs".  I uninstalled and got a refund.

I have found Lichi to have a lot of "known bugs".  I uninstalled and got a refund.   

acenothing Posted at 2017-3-14 10:19
I have found Lichi to have a lot of "known bugs".  I uninstalled and got a refund.

Hate to hear that. I really like it and it has never failed me. So much you can do with it.

My litchi also has worked wonderfully.  I did have one mission that half-way through sent some message (don't remember the exact words) that it lost satellite signal and just hovered.  I hit RTH and my bird came home, demonstrating that it still had satellite communication.  But that was one of 137 Litchi flights.  I use it mostly for FPV now with VR goggles.  Like a hawk, I am, flying between bushes and trees and light poles.  

If your mission is long the bird may be engaging RTH because the battery has dropped low enough to trigger Smart-RTH.   This probably won't happen unless your mission is in excess of 25,000' or more.  The flight computer leans conservative in this regard.  To run long missions you'll need to disable Smart-RTH.   Take note that if you do the bird will auto-land when the battery drops to 10%.  You can override this and fly home manually  if you are in RC range.  With a full battery you can reliably complete missions of 35,000-40,000' with a full battery.

Referencing another post here on Smart-RTH:  The Smart-RTH setting is stored in the bird.  You have to reenable it if you want it back on.  Disabling Smart-RTH DISABLES low battery RTH.  The bird will fly until the battery drops to 10%.  At this point the auto-land sequence will begin.

Also the "RTH on signal loss" setting is ONLY for when flying manually.  It does not apply to waypoint  missions.

The simple answer is that under Litchi, if the aircraft loses control contact with the RCX unit during the flight, it will continue the mission. But if it encounters any other serious problem, such as running out of battery power, it will NOT continue the mission, and frankly, you would not want to to try to finish. So either your mission is too long, the battery is too low, or something else is affecting the ability of the aircraft to complete it's set mission. It is not a fault in Litchi.