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A Litchi Mission Go Awry-or so I thought

danCER

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#1
Hello.
I have flown Litchi Missions ever since I bought my first Phantom 3 Standard, and my drone has always returned even though the signal was often lost for a few moments.
I have flown Litchi missions with my Mavic, but only a few.
I made a nice 8 minute mission, loaded it on my tablet, and headed for my location.
I started the Mavic Pro as usual, tested the movements and tap to focus and got it in position before loading the mission.
The Mavic was directly above me and maybe a little behind me before I loaded the mission. As soon as I hit "go", the screen said signal loss. I had no video feed or satellite map--they were frozen.
This had never happened to me right from the start.
And off went my Mavic Pro.
After wrapping my head around the problem I decided to stop the mission while I could see the drone.
It seemed to stop. I tried bringing it back but convinced myself that it was out of my control.
And off it went out of sight.
I tried leaving the waypoints screen, changing to fpv, and back to waypoints. Still no signal.
No video.
No drone.
I finally checked the controller screen. Altitude was being adjusted and distance increasing. .And I recognized the heights as waypoints that I set, so the mission was being run.
The tablet which is a Nvidia K1 Shield still said no signal.
The Mavic went by me as it finished its last leg of the programmed flight.
When it finished and hovered above me. I easily brought it back down and landed.
But the tablet screen and Litchi had never recovered the signal.
I decided to start it back up and fly a short flight. Everything was back to normal and Litchi had a signal and video feed.
I wonder if when I first raised the Mavic above me that the controller momentarily lost the signal as the mission loaded. For some reason, Litchi loaded the mission then lost the signal.
Every time I have almost lost faith with Litchi, Litchi comes through!
P.S. If anyone is interested I can post the video which shows the mission being stopped by me, then reversing a bit, then Litchi continued on with the mission.
 

Aerial-Pixel

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#2
Thank goodness you had it return to start. I normally have my Litchi Missions set to Hover at the end... I think I may change my process. Glad it worked out for you!
 
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waylander

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#4
Hi Dancer

Uhmmm, are you sure the fault lies with Litchi, I have a Nvidia K1 Shield , and I have observed many occasions with the K1 crashing and creating lots of different effects,eg "Lost Connection", screen frozen and not responding, app simply closing, etc etc and it does not matter which app, DJI GO, DJI GO4 or Litchi.
These type of events never seem to happen when I'm using my iPad Air 2, and a colleague of mine got so fed up with the K1 that he stopped using it, so there you go....

Regards Waylander
 

danCER

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#5
Hi Dancer

Uhmmm, are you sure the fault lies with Litchi, I have a Nvidia K1 Shield , and I have observed many occasions with the K1 crashing and creating lots of different effects,eg "Lost Connection", screen frozen and not responding, app simply closing, etc etc and it does not matter which app, DJI GO, DJI GO4 or Litchi.
These type of events never seem to happen when I'm using my iPad Air 2, and a colleague of mine got so fed up with the K1 that he stopped using it, so there you go....

Regards Waylander
I thought I was kind of praising Litchi in my post. :)
I have only used the K1 Shield to fly my drone. I have an iPad (2017) which I may test with Litchi.
I have never had this happen before right from the start. Maybe if I would have reconnected the cable, I could have got signal back.
Thanks for the info on your experience with the K1 Shield. I only have Litchi installed on it and use the tablet solely for flying.
 

danCER

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#7
One thing I failed to mention is that the mavic pro never lost signal on other missions.
I was definitely in range, so something was wrong with the connection. However the connection was fine up until I started mission, then I lost video on screen and signal lost warning.
I plan on flying same mission this eve to see how all turns out. I will post the results afterwards.
 
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Mossiback

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#8
Glad you got it back. Congratulations on setting your heights properly. Flipping it into and out of Sport mode would (should) have cancelled the mission. I suggest you set up a short and close mission and practice how to cancel it. I also set my takeoff position as the last waypoint so if the RC completely dies it should end up where it started.
 

danCER

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#9
Glad you got it back. Congratulations on setting your heights properly. Flipping it into and out of Sport mode would (should) have cancelled the mission. I suggest you set up a short and close mission and practice how to cancel it. I also set my takeoff position as the last waypoint so if the RC completely dies it should end up where it started.
Like I said, I have flown many Litchi missions over the years, and I have never lost a drone while using waypoints.
I guess when I tried to stop the mission by pressing red button on tablet screen, I was actually pausing it. Litchi support informed me of the sport mode switch to abort mission. I was used to the phantom switch from f to p.
And I have always set last waypoint back where I started.
Setting heights properly was never an issue.
 
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Marco Cantieni

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#11
I always end my missions back at start and "hover."
I‘m not sure this covers all kind of incidents. Back at start means at the altitude the bird had at the last waypoint?

RTH seems to be safer because the bird climbs to the predefined RTH altitude first, then flies back home. But maybe I‘m wrong
 
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danCER

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#13
I‘m not sure this covers all kind of incidents. Back at start means at the altitude the bird had at the last waypoint?

RTH seems to be safer because the bird climbs to the predefined RTH altitude first, then flies back home. But maybe I‘m wrong
When I said I always end my missions back at start, I meant the last waypoint is always near my first and me in my mission plan. If the Litchi mission aborted for whatever reason, hopefully, RTH would kick in at the altitude that was set and not the last waypoint altitude. So, yes, RTH is safer.. The way my missions end is the drone returns close to me and hovers, then I can bring it down. But my RTH settings are set much higher than my last waypoint height. Hope this helps or I understood your concern.
 

danCER

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#14
Just in case anyone is interested, I returned to the site and flew the same mission.
No signal loss the entire flight and video the whole time, too.
 
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lisadoc

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#16
I suspect that one of two things happened (when taking into account your follow-up posts):

1) The app froze/crashed on your device due to whatever issue. When you tried to cancel the mission on the device (instead of the RC), you weren't actually doing anything, and the Mavic flew the mission as commanded (since it had already been uploaded to the craft). Even if you restarted the app or it "unfroze", often the signal to the RC (and thereby the Mavic) will not return until you pull the USB cable and reseat it again. I almost always have to reseat the USB cable just to reacquire the "connection" if I have a problem with the device or even try to switch back to DJI Go from Litchi or Hangar 360 or Autopilot (or vice versa).

2) You somehow dislodged the USB cable slightly after uploading your mission. You are shifting the weight around/angle of the device when you let go with one hand to enable something on the screen or when you returned it back to the side of the controller. The mission loaded fine but the video and connection between the RC and device was cut off during the shift. Even if it was only momentary and the cable was properly seated after the brief misconnect, you would still have to pull and reseat the cable to reestablish the connection between the RC and device (see #1).

When you restarted your Mavic for a second flight, the connection was reestablished and the aircraft flew as expected.

The lesson I have learned is that whenever I have a connection issue between the RC and the device, when the RC continues to have a good connection to the Mavic, the best thing to do is to pull the USB cable and plug it back in. That small quick step fixes the issue almost 99% of the time. I often switch between apps (Litchi, DJI Go, Autopilot, and Hangar 360) during the same flight and I inevitably have to pull and reseat the USB cable to reestablish the connection between the device and the RC, all the while retaining complete control of the Mavic through the RC. You learn, through repeated experience, not to panic if the app has connection issues and remain quite calm whenever incidents such as yours happen.
 
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danCER

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#17
I suspect that one of two things happened (when taking into account your follow-up posts):

1) The app froze/crashed on your device due to whatever issue. When you tried to cancel the mission on the device (instead of the RC), you weren't actually doing anything, and the Mavic flew the mission as commanded (since it had been uploaded to the craft). Even if you restarted the app or it "unfroze", often the signal to the RC (and thereby the Mavic) will not return until you pull the USB cable and reseat it again. I almost always have to reseat the USB cable just to reacquire the "connection" if I have a problem with the device or even try to switch back to DJI Go from Litchi or Hangar 360 or Autopilot.

2) You somehow dislodged the USB cable slightly after uploading your mission. You are shifting the weight around/angle of the device when you let go with one hand to enable something on the screen or when you returned it back to the side of the controller. The mission loaded fine but the video and connection between the RC and device was cut off during the shift. Even if it was only momentary and the cable was properly seated after the brief misconnect, you would still have to pull and reseat the cable to reestablish the connection between the RC and device (see #1).

The lesson I have learned is that whenever I have a connection issue between the RC and the device, when the RC continues to have a good connection to the Mavic, the best thing to do is to pull the USB cable and plug it back in. That small quick step fixes the issue almost 99% of the time. I often switch between apps (Litchi, DJI Go, Autopilot, and Hangar 360) during the same flight and I inevitably have to pull and reseat the USB cable to reestablish the connection between the device and the RC, all the while retaining complete control of the Mavic through the RC. You learn, through repeated experience, not to panic if the app has connection issues and remain quite calm whenever incidents such as yours happen.
Thank you for the excellent comments.
I did mention above that I should have reconnected the cable which I have done in the past with my Phantom 3 standard. I just never thought of it mainly because I was afraid I was going to lose my $1,000 drone!
So I am sure I panicked a little.
I have heard but never tested that once mission is loaded you can even turn off RC, but I don't want to test that.
Even though I don't consider myself a novice when it comes to flying drones, it is amazing how you can forget even little things like removing gimbal guard.
But I am 57.
Thanks for everyone's replies.
 
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lisadoc

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#18
I did mention above that I should have reconnected the cable which I have done in the past with my Phantom 3 standard. I just never thought of it mainly because I was afraid I was going to lose my $1,000 drone! So I am sure I panicked a little.
Do it (turn off the app or disconnect the cable) while not on a mission, just to get used to the thought. Once you realize and get used to the fact that the craft stays completely in control, the automatic panic will fade and eventually go away completely. Just remember, you're flying with the RC... not your device. The device screen is only a pretty picture with more readouts and data. It's not much different than if your electronic dashboard in your car went dead while driving. It doesn't mean you're not still driving the car and in complete control with the steering wheel and pedals. You simply lost the information about how much gas you had left or what your current speed was (and even this analogy isn't true for your Mavic, since that information is still available on your RC).


I have heard but never tested that once mission is loaded you can even turn off RC, but I don't want to test that.
100% true. Litchi waypoint missions will continue without a signal to the RC at all (there are some limitations on features such as actions and gimbal changes, etc.). Eventually you'll need to reestablish the connection to aircraft in order to land it, but technically, with RTH properly configured, you could upload your mission, press play, turn off your controller, and then take a nap or go in to the house, and when you return later on, your Mavic should be sitting exactly where it took off from. I wouldn't want to do that of course, but I fly Litchi missions all the time where the signal is lost and waiting for it to come back into range (especially on well-established missions) has become rather mundane.
 

ScottyV

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#19
The lesson I have learned is that whenever I have a connection issue between the RC and the device, when the RC continues to have a good connection to the Mavic, the best thing to do is to pull the USB cable and plug it back in. That small quick step fixes the issue almost 99% of the time. I often switch between apps (Litchi, DJI Go, Autopilot, and Hangar 360) during the same flight and I inevitably have to pull and reseat the USB cable to reestablish the connection between the device and the RC
I've had some issues switching between DJI Go and Litchi while in-flight...sometimes it's seamless, but sometimes the app I'm switching to does not recognize the flight/connection. I've usually come back and landed, made sure everything was set up and working, and then take off again.

Question: When this happens do you reseat the USB cable to fix it, do you close the app you're switching to first and then reseat the cable and restart the app, or just reseat the cable without closing and the app will pick up the connection?
 

danCER

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#20
I've had some issues switching between DJI Go and Litchi while in-flight...sometimes it's seamless, but sometimes the app I'm switching to does not recognize the flight/connection. I've usually come back and landed, made sure everything was set up and working, and then take off again.

Question: When this happens do you reseat the USB cable to fix it, do you close the app you're switching to first and then reseat the cable and restart the app, or just reseat the cable without closing and the app will pick up the connection?
From what I have just learned, I would not change apps in flight. If you have both DJI and Litchi installed, usually when you plug in the USB it asks which app to open unless you told it to always open one app or the other.
So you plug USB in first before opening app.
I might be wrong but I first start tablet then turn on controller connected to tablet. It asks if I want to use Litchi when plugging usb in tablet, I say "0k'" and then I power on Mavic Pro.
 

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