Litchi waypoints: uploaded vs controller?

Member · Oct 30, 2016

Hello Pilots,

P3P user here. I'm new to Litchi and haven't used it out in the field yet. I want to plan the missions very carefully (leaving lots of extra altitude in different terrains, always going above trees, and open fields, etc) but based on past experience, the video feed will stop working during the mission because of its limited range. My question is regarding this situation:

1) Will the gimbal pitch change if I set it manually for the waypoints with interpolate? I have seen some discussions which suggest that the camera will not be changed if the RC is out of range. The official documentation doesn't mention this, or at least I haven't seen it. I do however recall seeing some posts claiming that it still worked. I would like to get a definite on this.

2) The help says this about the speed: "This setting is only in effect when the aircraft is in range of the remote controller. If signal is lost during the mission, the aircraft will continue the mission at the speed it was travelling at when it lost signal."

I'm just done planning a bunch of missions that were all along the lines of "go to this remote place, circle it slowly, come back". Without knowing or understanding the above warning, the drone would have certainly drained the battery while trying to return at say 2km/h.

This is a real buzzkill to be honest. Is this a Litchi limitation? Is it the Phantom's limitation? Does the SDK not allow for Litchi to program the specific speeds into the mission? Is there any chance for this to change? Will it be possible with the Mavic?

Thanks in advance for any clarification on this.

JohnnyB · Oct 30, 2016

Litchi will finish any mission when signal is lost. Just make sure you set it up precisely. Gimble pitch can be set with POI, as many as you like. Just set which POI you want the camara to look at, at each waypoint. Do some searching. There are excellent threads on here that explained all this for me. Search "Litchi".

Sent from my XT1096 using PhantomPilots mobile app
You can also set speed in each waypoint setting.

FlashBuddy · Oct 30, 2016

Oh, and you can manually control camera pitch, but only if in range and connected.

NoCo Drones

Member · Oct 31, 2016

Johnny Bellew said:
Litchi will finish any mission when signal is lost. Just make sure you set it up precisely. Gimble pitch can be set with POI, as many as you like. Just set which POI you want the camara to look at, at each waypoint. Do some searching. There are excellent threads on here that explained all this for me. Search "Litchi".

Thank you for your reply even though you answered the one question I didn't ask (i know the mission will be completed) and didn't touch any of the questions I actually asked (waypoints POIs without RC signal) and told me to 'do some searching' which was what I was doing for 3 straight hours before posting on this thread. Please don't take it the wrong way, I do appreciate any attempt to help, including yours, I'm just saying this to clarify I'm still looking for an answer to the original questions.

Member · Oct 31, 2016

FlashBuddy said:
Oh, and you can manually control camera pitch, but only if in range and connected.

By manually, do you mean controlling the pitch in realtime from the controller while it is in range, or do you mean manually set a pitch for the waypoint? The questions still stand.

1) If I manually set a gimbal pitch (in advance) for the specific waypoints and the drone gets to those points while the RC has no signal, will the gimbal move?
2) How come one can upload a whole mission to the aircraft with heading, coordinates, altitude, gimbal, but not speed? Is this a limitation of Litchi, the SDK or the P3 and will it change in the future?

MacCool · Oct 31, 2016

It's a limitation of the DJI flight controller software. You can't upload the speed changes to the drone. In LCMC (Lost Connection Mission Continuation), the custom flight controller goes away. In Litchi (IIUC) it reverts to the DJI flight controller on-the-fly. The downside to that is that if you do lose connection, you lose your RTH capability and with a dead battery the drone lands in place. In Autopilot, LCMC is actually something you have to enable at the start of the mission, which means that you give up that autonomous speed control in all LCMC missions.

Member · Oct 31, 2016

MacCool said:
It's a limitation of the DJI flight controller software. You can't upload the speed changes to the drone. In LCMC (Lost Connection Mission Continuation), the custom flight controller goes away. In Litchi (IIUC) it reverts to the DJI flight controller on-the-fly. The downside to that is that if you do lose connection, you lose your RTH capability and with a dead battery the drone lands in place. In Autopilot, LCMC is actually something you have to enable at the start of the mission, which means that you give up that autonomous speed control in all LCMC missions.

Thank you, that was very insightful.

Just to make sure I understand this, the flight controller software is part of the firmware itself. correct? And if so, does this mean that there is a glimpse of hope that a new firmware will allow for this in the Phantom 3? Or do you think that is this something that's unlikely to be ever added, even with future DJI drones?

Ps/side note: this may all be moot for me: I tried my first waypoint mission ~20 minutes ago, 'Unfortunately Litchi has stopped'. Time to Google again. :-(

MacCool · Oct 31, 2016

Yes, and the SDK doesn't allow overwriting the firmware. I'm sure that DJI could update firmware to do whatever they want, so yeah, there's hope. There's always hope. I have no idea why speed or gimbal angle aren't allowed by the DJI flight controller after LCMC, so no idea if it's likely they'll change.

I don't know why Litchi stopped running. I've never had that happen. IIUC, that's usually a problem with the device it's running on. Both Litchi and Autopilot tend to be very stable on iOS devices but the nature of Android,,,multiple platforms, multiple mfgr tweaks to the Andoid OS, etc tends to make Android a little twitchy sometimes. What mobile device are you using?

Member · Oct 31, 2016

I can handle a little twitchy, the app stopping just when I'm asking it to upload the mission is not so great

I was hoping to find a SERP full of "Litchi has stopped" threads but it's surprisingly empty so you're probably right about it being stable generally. Apparently I'm governed by sod's law... I'll try to update the Android and reinstall Litchi on the device.

Member · Nov 1, 2016

Update: after almost bricking my tablet trying to root it and then reinstalling the latest firmware, Litchi waypoints are working! Two missions completed so far, I love it.

FlashBuddy · Nov 2, 2016

Did you manually control your gimbal pitch from the controller?

Member · Nov 2, 2016

It was all waypoint defined, interpolate. I didn't really expect to have signal, but this time the range was better than it used to be and I saw clear video feed during the whole mission.

Side note: after I launched the drone ~20m above me, video feed was lost, got 'Signal Lost' error on the tablet. It was showing that for a minute or two until I disabled the wifi. I almost forgot how much difference that makes.

JohnnyB · Nov 2, 2016

Member said:
It was all waypoint defined, interpolate. I didn't really expect to have signal, but this time the range was better than it used to be and I saw clear video feed during the whole mission.

Side note: after I launched the drone ~20m above me, video feed was lost, got 'Signal Lost' error on the tablet. It was showing that for a minute or two until I disabled the wifi. I almost forgot how much difference that makes.

Sorry for the unanswered questions earlier. Have one for you... Just to clarify, were you referring to your tablet that you disabled WiFi on? I hadn't ever thought about that, but also haven't ever lost signal on my P4 yet. Just wondering if this is something I should do.

Sent from my XT1096 using PhantomPilots mobile app

Member · Nov 3, 2016

Johnny Bellew said:
Sorry for the unanswered questions earlier. Have one for you... Just to clarify, were you referring to your tablet that you disabled WiFi on? I hadn't ever thought about that, but also haven't ever lost signal on my P4 yet. Just wondering if this is something I should do.

It's definitely a good idea to reduce interference to a minimum. Since the tablet is very close to the controller, that's the first place to start. Try how much range you get with and without the wifi enabled on the device sitting on top of the controller. Also consider the phone's wifi&3g in your pocket if you're using a tablet.