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  1. AGreenway

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    I recently attempted a Litchi Waypoint Mission that I had already set up on my computer at home.

    The first thing I noticed, but didn't realize, is that it's entirely possible to load up a mission and simply hit the Play button on the tablet, and watch the drone take off from the ground and begin its mission automatically. Not a cautionary observation, just a pretty cool feature that I wasn't aware of (although in hindsight I guess it's good to be aware of your surroundings to ensure that this type of automation won't lead to a collision, or just launch the drone manually first).

    The second thing that happened was that once the drone got about 1.5 km away from me (not going to convert to miles, sorry), the signal became weak, and I lost the RC connection, which I wasn't expecting as I had a very clear line of sight (and normally I don't lose the connection until a fair bit further away in such conditions). I was already aware that in Litchi, the drone will complete its mission even if you lose the signal, and this freaked me out a bit as I wasn't 100% certain that I had set the altitude high enough to clear the ridges coming off the hill I had set as a Point of Interest.

    So I opened up the DJO Go app, and for some reason, this app was able to get a (weak) connection, and thankfully I was able to activate RTH (not sure if I could have just done that regardless in the Litchi app?).

    Once the drone returned home, I set up a very small and close mission to see how it behaves once you turn off the RC. Sure enough, it continues to complete the mission. I cannot understand why Litchi does not give you the option to abort the mission if the signal is lost, and RTH! It just seems incredibly stupid to me.

    Another thing that was rather alarming during this test mission, was that the drone starting to hover erratically in place, and would not move, and it looked like it was caught in some weird turbulence. I panicked and aborted the mission. Much later, it occurred to me that it was doing this because the sun was quite low in the sky and was shining into it, which was perceived to be an obstacle and so the drone wouldn't move forward because its forward obstacle avoidance was switched on. According to the Litchi manual, if the drone's battery reaches the critical level during a mission and there is no RC connection, it will simply land right where it is at the time. It is therefore possible for the drone to get "stuck" with no RC connection when the sun is shining into it, reach its critical battery level, and descend into trees or other obstacles and get destroyed and/or completely lost.

    So from now on I am going to be much more weary of how I use Waypoint Missions. I will not do them unless I can see the drone at all times, or I am 100% confident that it will clear all obstacles and the sun won't shine into it (and I don't think that switching off forward obstacle avoidance is a very good solution unless the drone remains in sight at all times).

    Are there any other steps I can take to overcome these limitations?
     
  2. Mark The Droner

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    If you've lost communication, you cannot communicate. That means you cannot initiate RTH. There's nothing stupid about it.

    If you're proposing that Litchi add some kind of option to auto-RTH after losing signal, that's different.
     
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  3. AGreenway

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    I think you've completely misread what I wrote. I maintain that it is incredibly stupid for Litchi not to provide the option to RTH automatically if the RC signal is lost. This is entirely possible from within DJI Go settings.
     
  4. AGreenway

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    I see that you have since edited your initial response to me to sound a bit more reasonable. (That second sentence you wrote was NOT in your initial post.) I wish people would read other people's posts properly before jumping down their throats.
     
  5. Mark The Droner

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    Yes - I read "option to abort the mission" as an option on the app during the mission, not as an option before launching the mission...
     
  6. AGreenway

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    Ok, explanation accepted. :)
     
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  7. CornelDRAW

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    With all due respect to the unfortunate accident I would like to say that those who use Litchi do exactly for possibility of using drone beyond radio link limitations.
     
  8. AGreenway

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    I think you'll find that that majority of users do NOT use Litchi when loss of radio link is a possibility. I could be wrong, but based on what I have read over various forums, most users do not like this rather scary feature.
     
  9. Mark The Droner

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    I don't think this is correct. Continuing the mission is an advantage. It allows the pilot to put his aircraft in unreachable areas. It's an option - it's something that's done on purpose, not by accident. Yes it can be scary, but some would call it exhilarating. And one can follow the aircraft live as it flies out of range - with a good GPS tracker such as Flytrex Live, although I don't think they have one for the P4 yet.
     
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  10. AGreenway

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    I can see that it would be advantageous for some missions. But I'd still at least like the option to trigger RTH after loss of signal. A GPS tracker would be nice too.
     
  11. jwt873

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    I agree that it is odd for Litchi not to provide RTH on signal loss.. It shouldn't be that hard to institute. I'm sure most wouldn't use it, but I don't think you can have too many options in a software package.

    On the sun interfering with the object avoidance... I've run into this quite often. (Just this morning as a matter of fact while flying under DJI-Go). Sun interference can mess up Litchi missions. You can avoid this by turning off object avoidance. But when you do this, you have to make sure there will be nothing in the way during a mission.
     
  12. AGreenway

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    So you think most people wouldn't use RTH on signal loss? Interesting. You could be right. However, while I can see why professionals with extra GPS tracking support might not care, I would have assumed for the average drone pilot, there would be not much worse (apart from crashing) than signal loss with no immediate RTH trigger.

    As for the sun, I'm just going to have to turn off obstacle avoidance in future if I anticipate the sun getting in the way.

    In either of the above situations, confidence in the mission path is key!
     
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  13. jwt873

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    I've never done a poll, I'm just assuming what might be true. One of the reasons people buy Litchi is to extend the range of the Phantom.

    But like you, I'm uncomfortable having an expensive bit of kit completely out of range and 'doing its own' thing without me being able to intervene.
     
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  14. CThruU

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    Unscientific poll answer here. I bought Litchi completely for the ability to continue the flight after signal loss. However, I could certainly understand how it would be helpful to provide a user-selectable option to either continue or RTH on signal loss.
     
  15. SoundByte

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    Autopilot provides this option!
     
  16. jogforfitness

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    Though this is not quite the solution you're looking for but, it may help. I've never tried it. Take a look at the setting SMART RETURN HOME in the DJI Go app. If its ON, then when running a Litchi mission if the battery drops to a certain critical level, it will allegedly execute a RTH. I've heard it was not unusual for this feature to kick in prematurely from time to time. I believe I read this flavor of experience encountered by someone in this forum. You'll have to research more as since I'm just repeating info and could be misspeaking.


    Sent from my iPad using PhantomPilots
     
    #16 jogforfitness, Aug 8, 2016
    Last edited: Aug 8, 2016
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  17. SoundByte

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    That is a function of the GO app, not Litchi. The Go app is not running while using Litchi. In any case SRH would not help if the RC looses contact.


    Sent from my iPad using PhantomPilots mobile app
     
  18. jogforfitness

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    This may be helpful. Look for Dirty Bird replies, etc. Litchi app. Whats your thoughts

    It's my assumption that settings in DJI Go app carry over to Litchi app. I run missions in Litchi with DJI app CLOSED. Wish my answers could be more definitive.

    Sent from my iPad using PhantomPilots
     
    #18 jogforfitness, Aug 8, 2016
    Last edited: Aug 8, 2016
  19. SoundByte

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    That would depend on weather the craft keeps track of the SRH point or the app does. Because the SRH is dynamic (ie:always changing as the telemetry changes) I am just making an assumption that it is the app that controls it, not the craft. Be that as is may, the discussion is about lost contact and not bingo fuel. I think Litchi should have provided the option but as it sits now, if you want it you'll need to use Autopilot or the GO app for waypoint missions. There maybe another 3rd party app that has it as well.
     
  20. John Locke

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    Autopilot and GO apps can't upload a mission to fly 100% autonomous like Litchi. They have no choice but to RTH or hover in place upon signal loss. That's what sets Litchi apart from all others.

    However I also think adding an AUTO RTH option in Litchi for those that expect to always have a control connection is good suggestion.