Setting waypoint altitudes on location

[Neil Moore]

Hi,
I had trouble today setting up my mission on location.
I didn't start the mission plan with Mission Hub at home because I didn't know where or what I'd be shooting.

On location, after the P4P set it's home point, which I believe was (should have been) set to Zero altitude, I flew to where I wanted Waypoint #1 to be and set it. I then flew to each Waypoint setting them with my control key.
I reviewed the mission and all Waypoints seemed to be what I expected. I did NOT have AGL checked so that the P4P would refer only to the Home Point altitude. I named it and saved it. ( I did have a good cell connection so the mission saved and loaded without problem)

When I started the mission, it flew to the accurate ground point of Waypoint #1 but at a much higher altitude than was set. It then continued to each Waypoint but at seemingly random altitudes; certainly unrelated to the altitude that was set in the mission.
I tried resetting the home point by restarting the P4P and letting it set the Home Point again. Same result.
I tried re-doing the mission completely. Same result.

So, I'm puzzled.
Has anyone experienced this?
Any ideas, suggestions or wisdom?

Thanks,
Neil

 

[Fly Dawg]

When I started the mission, it flew to the accurate ground point of Waypoint #1 but at a much higher altitude than was set. It then continued to each Waypoint but at seemingly random altitudes; certainly unrelated to the altitude that was set in the mission.

Two points. One, the GE mapping ground profiles are not very accurate. You should also take in to account that the aircrafts barometer can be off as much as 20ft, more or less depending on weather conditions and where you are flying. 2... When changing altitudes in Litchi, these are angular paths, so that as well must be taken in to account in your mission profile.

 

[sar104]

That obviously didn't work as planned but, without seeing the mission file and the flight log (preferably the DAT file that will show the mission upload data), it is hard to diagnose what might have happened.

 

[Neil Moore]

Thanks guys.
I show my ignorance when I have to ask "what is GE"?
I wondered about the barometer but I would think it would be the same reading within the minutes between setting the point and flying it. Is there more to this than meets the eye?
This does bring to mind, I thought the barometer was the 2nd monitor control and GPS was the first. I guess there is more detail to learn about that.
As for angular paths, I have run into problems with curves that were set too large before. Lessons learned there a while ago! I will give that a look and some observation.
I have never downloaded the flight log before. I believe I've read somewhere here how to get that. I'll find that and see what I can learn from that data.

Thanks again for the responses and ideas. I'll give it some study and see where I went wrong.

 

[sar104]

Thanks guys.
I show my ignorance when I have to ask "what is GE"?
I wondered about the barometer but I would think it would be the same reading within the minutes between setting the point and flying it. Is there more to this than meets the eye?
This does bring to mind, I thought the barometer was the 2nd monitor control and GPS was the first. I guess there is more detail to learn about that.
As for angular paths, I have run into problems with curves that were set too large before. Lessons learned there a while ago! I will give that a look and some observation.
I have never downloaded the flight log before. I believe I've read somewhere here how to get that. I'll find that and see what I can learn from that data.

Thanks again for the responses and ideas. I'll give it some study and see where I went wrong.

GE refers to Google Earth and its digital elevation model (DEM). It can have errors, especially in steep terrain, but it probably doesn't account for the issue that you described. The barometric altitude should be good to within a few meters over the duration of a flight.

If you don't want to post the mission file then take a look at it and see what the altitude of each waypoint is in the mission profile. That will be altitude above the takeoff point if you don't have the AGL option checked. Then check that against the actual ground elevations shown in Google Earth to see if they are correct. It should be trivial to identify any errors.

 

[Fly Dawg]

I show my ignorance when I have to ask "what is GE"?

Google Earth

I thought the barometer was the 2nd monitor control and GPS was the first.

The barometer is you altimeter. Nothing to do with GPS.

As for angular paths, I have run into problems with curves that were set too large before.

By this I mean between waypoints. When you change altitude from one waypoint to the next. The aircraft will gradually ascend or descend as it progresses to the next waypoint. The closer your waypoints are together, the faster the ascent or descent rate.

You can upload your device flight data to the link below. If you wish others to look, share a link back here to that. Instructions are on the link. Also share you mission from the hub here as well for a baseline.

LOG VIEWER

 

[Neil Moore]

Thanks again guys.
Sorry to be slow on the nomenclature as well as the data look up. Getting up to speed fast though.
Interesting about the logs.
I have looked at both the Litchi and DJI flight logs/records.
I will need to refly this mission as the records do not represent the mission I flew...Although, one record seems to have all the flights recorded in one huge record....:-o