Because Forced Landing at 25% of battery?

[Testman]

Today, after a perfect flight, my Mavic Pro is induced to forced Landing with 25% to battery load. Fortunately I see the alert in DJI Go 4 and opposed to Landing with sticks of radio, but in case of loss of video the results may be a disaster. Why the drone lands at 25% instead at 10% of battery load?
This is the fly log:
Phantom Log Viewer - PhantomHelp.com

 

[msinger]

Forced Landing mode was initiated when the throttle was in the full down position and the downward sensors detected the ground was near. You can prevent that from happening by disabling the "Landing Protection" setting in DJI GO.

 

[Testman]

Forced Landing mode was initiated when the throttle was in the full down position and the downward sensors detected the ground was near. You can prevent that from happening by disabling the "Landing Protection" setting in DJI GO.

View attachment 11247

Thank I understand, but the feet was 136 and ground was not near.

 

[msinger]

Check out the "VPS Altitude" column in the flight log you posted above. The downward sensors thought the ground was near.

 

[Testman]

Check out the "VPS Altitude" column in the flight log you posted above. The downward sensors thought the ground was near.

View attachment 11248

I remember the real altitude was 40 metres when appeared forced landing advise. The other altitude in the post is 136 feet.

 

[msinger]

That sounds about right. 136 feet is very close to 40 meters.

 

[Testman]

The imu altitude (136 piedi) was the real altitude of Mavic. I do not understand why the forced landing was ordered at 25% of battery load instead 10% at 136 feet of altitude.

 

[msinger]

It's not possible to auto initiate forced landing mode at a set battery percentage. It is auto initiated when you move the throttle stick to the full down position and the downward sensors detect the Mavic is at or below 0.5 meters from the ground.

 

[Testman]

It's not possible to auto initiate forced landing mode at a set battery percentage. It is auto initiated when you move the throttle stick to the full down position and the downward sensors detect the Mavic is at or below 0.5 meters from the ground.

I remember perfectly, I was in flight at 40 metres of altitude with 25% of battery load at 500 metres to home position, when i see the forced landing advise in my ipad mini 4. I immediatly work with the sticks to prevent the mavic landing in the fields. I was able only basic flight at very low speed and drive my Mavic over my home Platform.

 

[Testman]

Other opinions?

 

[Pedro]

Other opinions?

Seriously? You're doubting @msinger? Read and learn..

I would suggest that is not only an unwise thing to do but a waste of time. Next time you want some proper advice he might not feel so inclined to give it (although I suspect he would).

 

[msinger]

I immediatly work with the sticks to prevent the mavic landing in the fields. I was able only basic flight at very low speed and drive my Mavic over my home Platform.

If you toggle the sport mode switch or move the throttle to the full up position (if running the latest firmware), forced landing mode will be cancelled.

 

[flightmike]

Msinger, Very confusing! What is the difference between IMU and VPS altitude? Shouldn't they be the same? Why would it force land if it had 136 ft IMU altitude? Where does it get the VPS altitude to determine to land?

 

[Testman]

If you toggle the sport mode switch or move the throttle to the full up position (if running the latest firmware), forced landing mode will be cancelled.

I' m in .400 firmware. I was able to move the sticks like a10% battery situation when begin landing of emergence.

 

[Testman]

Msinger, Very confusing! What is the difference between IMU and VPS altitude? Shouldn't they be the same? Why would it force land if it had 136 ft IMU altitude? Where does it get the VPS altitude to determine to land?

I do not know. In the flight record of the accident the two altitude are 136 and 0.3 feet at the same moment.

This is the flight record before this:

Phantom Log Viewer - PhantomHelp.com

 

[msinger]

What is the difference between IMU and VPS altitude?

IMU is the altitude (above the takeoff point) estimated by the IMU using data from the barometer. VPS (Vision Positioning System) is the altitude detected by the downward sensors.

FYI, "IMU Altitude" and "VPS Altitude" are column names I created in my flight log reader. DJI does not use those terms.

Shouldn't they be the same?

They should rarely be the same since the IMU altitude is the altitude above the takeoff point and the VPS altitude is the altitude above the ground at the current location. The downward sensors normally don't detect the ground unless the Mavic is close to the ground. However, reflections off the surface of water/trees (for example) sometimes cause the sensors to incorrectly detect the ground is near.

Where does it get the VPS altitude to determine to land?

That data comes from the downward sensors.

 

[Kilrah]

VPS altitude is the altitude read from the sonar sensor. If something is disturbing it (external interference, a leaf stuck on the bottom,...) it may read erratically.

 

[msinger]

I was able to move the sticks like a10% battery situation when begin landing of emergence.

Yes, I can see you were operating the sticks in that manner in your flight log. Your Mavic was not performing an emergency landing though.

 

[Testman]

Yes, I can see you were operating the sticks in that manner in your flight log. Your Mavic was not performing an emergency landing though.

I'm confused. So the forced Landing in the flight log what does it mean?

 

[msinger]

So the forced Landing in the flight log what is means?

It means your Mavic thought it was close to the ground and it thought you were trying to land since you had the throttle in the full down position. If you don't want your Mavic to assist in the landing process, then you must disable the "Landing Protection" setting.