Be careful of Litchi's "Relative to Ground" flight plan.

[Crusty Raven]

Set up PP4 Litchi flight plan down a hill and around some buildings and back home using the relative to ground scenario and flew a perfect mission. Then I tweaked some way points and re-flew the plan. I noticed that when it reached the low point it seemed that the drone was lower than before. Well, suddenly, tree limbs appeared and WHACK, leaves were flying. Somehow I backed out and regained flight, switched to Attti mode, from p mode, and gained altitude and returned home. NOW, my only explanation re: the flight plan is that Litchi doesn't lock in the "Relative to Ground" but my tweaking caused the "Relative to Home", to kick in. I looked at the plan and it had switched itself back to the "Relative to Home" without any input from me other than tweaking some way points. From here forward, I am checking this point each time before I fly.

 

[tevek]

From my experience, each time you open the mission, it will default to Relative to Home. I suspect that the default is in place based on the assumption that you are going to edit the mission and need to change the mission parameters. Certainly a trap if you fail to notice that change and as you have noted, can end badly. I also use POI as my last action when planning a mission so that if I inadvertently tap the screen without noticing it, I end up with an additional POI and not a WP which caught me out once with the drone heading off to Israel.....

 

[Fly Dawg]

I noticed that when it reached the low point it seemed that the drone was lower than before. Well, suddenly, tree limbs appeared and WHACK, leaves were flying.

Always without exception, give an additional of at least 50ft in altitude from anything that is "Estimated" for any waypoints in a mission. Also you have to consider your flight plan's minimum AGL, then include taller trees, or other interferences in the flight path for the mission and for RTH if needed.

 

[GrammatonxXXxCleric]

Also take into consideration the altitude error reporting of it's actual current altitude. I've found that once you climb past 100ft up or so then the rest of the flight is incorrect.

 

[Crusty Raven]

Always without exception, give an additional of at least 50ft in altitude from anything that is "Estimated" for any waypoints in a mission. Also you have to consider your flight plan's minimum AGL, then include taller trees, or other interferences in the flight path for the mission and for RTH if needed.

One other thing that I haven't figured out with my new PP4, when it returns from a mission, using Litchi, and, I began to bring it down, it won't hover in one place if I drop the controls. It starts wandering with the wind or by itself. With DJI GO, it is perfectly stable. I always calibrate before the flight.

 

[diott]

I am struggling a bit with the Relative to Home (RTH) vs Relative to Ground (RTG) features as well. Too be honest I see no value in defining missions using RTH! We fly over obstacles that have a height from the ground and it is much easier to think in RTG terms. At a minimum, Litchi should update the IOS display to show both value using the same yellow / white paradigm. It's relatively useless to setup a mission in Hub defining RTG values only to view RTH values when you get to the site and are reviewing the waypoint mission! I need to get my feelings to the Litchi folks, just don't know the best method to do that

 

[BigAl07]

I need to get my feelings to the Litchi folks, just don't know the best method to do that

Here you go @diott :

[email protected]

or

Litchi on FaceBook

 

[BillH]

I have noticed the same thing. I create a mission RTG and save it, then load it into the hub to fly, and notice that it has defaulted back to RTH. This is bad news folks, and it is going to cause a lot of mission flyers to crash if they forget to check the elevations of the way-points prior to flying the mission. Isn't there a way to set the default to RTG?

 

[Sandgroper]

Set up PP4 Litchi flight plan down a hill and around some buildings and back home using the relative to ground scenario and flew a perfect mission. Then I tweaked some way points and re-flew the plan. I noticed that when it reached the low point it seemed that the drone was lower than before. Well, suddenly, tree limbs appeared and WHACK, leaves were flying. Somehow I backed out and regained flight, switched to Attti mode, from p mode, and gained altitude and returned home. NOW, my only explanation re: the flight plan is that Litchi doesn't lock in the "Relative to Ground" but my tweaking caused the "Relative to Home", to kick in. I looked at the plan and it had switched itself back to the "Relative to Home" without any input from me other than tweaking some way points. From here forward, I am checking this point each time before I fly.

Remember to always have your drone on and connected when altering settings. I found this out early in the game.

 

[BillH]

OK, now I have a question about creating a mission in Google Earth. If you bring a pre-planned mission in from Google Earth as Relative to Ground, will the hub screw that up also and ruin all your pre planned elevation? The more I find out about Litchi, the less I'm wanting to use it.

 

[Fly Dawg]

OK, now I have a question about creating a mission in Google Earth. If you bring a pre-planned mission in from Google Earth as Relative to Ground, will the hub screw that up also and ruin all your pre planned elevation? The more I find out about Litchi, the less I'm wanting to use it.

NO. They work just fine.

 

[bsartist]

Is the warning in the original post still valid? If so, on what platform(s)?

After seeing this awakened thread I tried it in the iOS app and I don’t see them switching to relative to home.

If I select all waypoints and select edit, then I see the default is relative to home.