Litchi waypoint altitude bumps

[Steve99]

Hello

FIrst post, so hello everybody.

I've just started flying Litchi waypoint missions with my Phantom 3 Pro and an iPad Air 2. I'm flying straight from one waypoint to a second, both set to the same altitude.

Everything goes fine apart from 'bumps' in altitude along the way. The drone flies for about 10 seconds and then it pauses slightly, revs up and lifts maybe a metre (judged by eye), this then repeats along the course. At the end of the mission it's at the correct altitude.

Can anyone advise as to what's happening and/or where I'm going wrong? Thank you.

 

[RodPad]

Welcome to the Forum!

Hum,
Are you concerned about elevation between the way points?

1 meter being about 3' seems no big deal to me.

What is the distance between way points?

What is the AGL of these way points?

Since this your first posts, did you know a barometer is used for altitude?

I'm also surprised your post is more that 24 hrs old
Anyways keep the questions coming, others will reply and you can still ask for a refund on your membership

Rod

 

[dwallersv]

What altitude are the waypoints?

I've never seen this sort of behavior before myself. Perfectly smooth flight between waypoints.

However, if you're flying relatively close to the ground -- less than 30' or so, this is where the ultrasonic ranging sensors underneath the aircraft kick in for precision height positioning -- it may be causing some collision avoidance behavior or something.

This video is one of the most amazing Litchi flights I've ever seen. Anyone using Litchi and the P4 should watch this -- it's nine and a half minutes, but enjoyable, and worth the time.

Anyway, during this mission, contact is lost, and it flies very close to the ground. Changes elevation automatically to avoid bushes, a barbed-wire fence, even a house.

So, if you're trying to do some cool ground-hugging Litchi mission, those pauses and elevation changes may be exactly what you see the P4 doing in this mission (despite the clickbait title, it doesn't crash ):

 

[Steve99]

Thanks very much for the replies, you two will always be Phantom heroes to me

I was flying simple 2 waypoint missions. both at 40m, 250m apart and maybe a metre difference in ground level, flying mostly over grass with some leafless trees around. The altitude showed as constant in Litchi, but the upward 'bumps' came with a deceleration which ruined the video shot.

I tried it again with DJI GO App waypoint mission and got the same behaviour, so litchi was off the hook.

I then read about the ground positioning sensors (VPS) as described in dwallersv's post above and turned them off. I think this may have sorted the problem, although I've been so busy recording waypoints on the fly today that I only tried a couple of repeat missions (rare and perfect flying/fliming conditions in my part of the UK today).

Thanks again, happy skies.

 

[dwallersv]

Aha! "Mostly over grass" -- here's the issue with the VPS: It doesn't do will with anything for which a discernible visual pattern can't be seen. Uniform color and texture can really mess with it, and a nice uniform field of grass could cause problems, although this would be the first time I've ever heard of that specific issue (i.e. VPS getting confused by a field of grass).

The place you REALLY need to make sure you remember to turn it off is over flat, smooth water (or any reflective surface). Reflections tend to move with the aircraft, fooling it into thinking it's not moving. Posts with Phantoms shooting off in some direction after getting over water are ubiquitous.