Downward Sensors Flying Over Creek

[GAGuy]

Today I was flying over a creek with swift water. The Mavic had issues with maintaining height and almost lost it in the water twice. Keeping in mind I'm having to fly low to get this footage. About 4-6 feet. So I figured I'd try turning them off. My question is... I've heard that the Mavic uses these for stabilization and now I could have drift. That might be even worse. Anyone with experience on this? Thanks

 

[tcope]

The only way the downward sensors affect level above the ground is if it's about 1 foot off the ground and you fly up a _very_ gradual incline. Other then that, it does not affect flight. So it should not have affected your flight and turning off the downward sensors should not change anything.

To give another example... when you are landing and pressing down on the stick, there is a point where the Mavic stops for a moment and then starts to land. This happens at about 1'. This is where the downward sensors are kicking in. But again, unless there is a _very_ flight incline, they _will not_ change the flight height.

 

[Turnerm]

The downward sensors can be fooled by light reflecting off of the water. It makes it think it's closer to the surface than it really is and it will begin to rise... which is dangerous when flying over a creek because the tree canopy is likely pretty low. This exact thing happened to me. Turning off the downward sensors solved my issue. Just be sure to keep the drone close to you so that you can easily see what it's doing. It can be difficult to notice it drifting if you're watching the FPV feed... Especially when only a few feet matters.

 

[GAGuy]

Thanks....
Actually the drone kept DROPPING in altitude. I was flying about 5-6 above and it constantly had trouble maintaining the height. I did find this on another thread.
The ultrasonic sensors project sound out like radar. The sound waves come back and depending on the frequency and speedy that they come back at the drone knows how high off the ground it is and can tell if it's going up or down. It helps maintain altitude. WATER absorbs these mostly so that's why you need to disable them while over water.
The camera sensors look at the pattern on the ground and try to maintain the picture they see when the drone is hovering in place. It will compensate for wind by trying to keep the picture the same. It also isn't just for use indoors as it helps the drone maintain horizontal accuracy. It doesn't work well with water because the waves are a moving subject... thus making it confused. It also doesn't work well in low light situations. Hope this helps. Happy flying gentlemen. Oh and yes it is in the app under equipment and advanced setting I believe or under the sensor/ OA menu.

 

[Mako79]

If you fly too low, it will follow the flow of water. Move a little higher so the belly camera can track some thiing else to hold position.

 

[GAGuy]

If you fly too low, it will follow the flow of water. Move a little higher so the belly camera can track some thiing else to hold position.

Thanks.. I can't . Low canopy of trees. I'll practice over the swimming pool.

 

[2nckayakers]

So I have found where water isn't the only issue that can affect the sensors. I was flying low over a sunflower field this past weekend and I kept noticing that it wouldn't hold position during hover. It was moving all over the place. Without being there you would first think that there was some wind, but it was a calm day. After I got back home and started looking at the video I realized that the prop wash was blowing the sunflowers all over the place. So I went back the following day to experiment and if I was up about 3 feet from them everything was rock solid but if I was within about 2 feet it started to squirm all over the place.

 

[Brojon]

Good info - thanks!

 

[Dr Dave]

I seem to recall there being something in the DJI documentation for MP stating that the vapor pressure off of a body of water can affect the sensors.

I'm in Hilton Head Island right now and doing some early morning flying - over the marshes, etc - all this makes me nervous...lol

 

[2nckayakers]

I seem to recall there being something in the DJI documentation for MP stating that the vapor pressure off of a body of water can affect the sensors.

I'm in Hilton Head Island right now and doing some early morning flying - over the marshes, etc - all this makes me nervous...lol

I love flying over marshes. I just try to stay above the grasses so I don't accidentally become a lawn mower.

 

[Turnerm]

I seem to recall there being something in the DJI documentation for MP stating that the vapor pressure off of a body of water can affect the sensors.

I'm in Hilton Head Island right now and doing some early morning flying - over the marshes, etc - all this makes me nervous...lol

I took my Mavic to HHI back in May. Had a blast. We were staying right on the harbour and I was able to fly it all over the place. Got some decent footage. I had a lot of fun flying it up number 18 and around the lighthouse.