Horizontal Drift Too High

[Renier]

I recently purchased an H520 for filming and documentary purposes from our new hospital ship, the Global Mercy.

We are currently at sea on our sea trials, and I am experiencing some issues taking off with GPS assistance.

The device is prompting "GPS Horizontal Drift Too High" I manage to take off and fly without GPS, activating the "Indoor" Mode but find Drifting in winds is high due to no GPS assistance to hold position to take certain shots etc. This is because we are sailing and yes, I do have a horizontal drift of about 7.5 m/s.

Can any one advise on how to update the parameters set that would allow take off with GPS assistance with a horizontal drift of about 14.5 knots or 7.5 m/s.


I understand it will affect the RTL function; however, if the vehicle could follow the remote unit's GPS for returning


Thank you in advance, and I look forward to a reply...

 

[Gadget2628]

Hi Renier

The horizontal drift error message is new for most users since an update in January but more on that later.

Firstly have you calibrated all of the sensors?

Generally the bird needs to have the compass calibrated if the drone is more than 8 km (5mile) from where it was last calibrated. If you don't calibrated you run the risk of a flyaway.

The H520 will need to be calibrated HOWEVER the system is EXTREMELY sensitive to interference from lots of steel and iron. Owners manual advises no metal objects within 10 feet when calibrating. Your ship may make calibration impossible.

Takeoff in angle mode or using a Datapilot mission cannot occur without the GPS being properly calibrated. RTL is also problematic if the GPS hasn't been calibrated.

Flying manually (Atti mode for DJI folk) means that the drone will slide around a lot. Unfortunately I don't think it is possible to adjust the flight controller parameters to do what you want. I also think you would need to be able to adjust the parameters each flight as wind conditions will be different for each flight. Ultimately the biggest hurdle would be having a non-GPS reference that the flight controller and ST16 could recognise.

If you are able to successfully calibrate the bird I would strongly suggest that you set the Return Home Mode to RCS (Return to Control Station) before you do anything else. This is because you will be operating from a mobile platform. The normal RTL will send the drone to where the ship was when you started the flight.

Members are still working out all of the causes for the Horizontal Drift error message. It is commonly seen at startup and disappears quickly. My own experience is that it occurs with my machines when the drone is still initialising but the controller has got a 3D lock. It can also happen when the controller can see the sky but the drone can't.

I think you may be stuck with manual flight mode whilst on the ship. If you can get ashore at some point you can calibrate the drone and maybe get some good shots when the ship leaves the port.

 

[h-elsner]

As far as I know PX4 Autopilot has two parameter to control this behaviour in pre-flight checks.
EKF2_REQ_HDRIFT: Maximum horizontal drift speed to use GPS, maximum is 1m/s
EKF2_GPS_CHECK: To switch on/off the different checks.

Please be aware that it may be very dangerous to change the parameter because it may cause unexpected behaviour of the drone in different manners.

I do not know if H520 allows to access to those parameters.

Redirecting to latest version of document (main)

br HE

 

[Rayray]

Somewhat familiar with this. I suggest after starting the H520 in normal mode you wait a bit. Touch the bird symbol at top and watch GPS Sat acquisition. I find after 15-16 Sats that the offending msg will go away.

If this does not work, you may be stuck with manual (non-GPS) operation. Also, be careful landing...
Good luck

 

[vr-pilot]

EKF2_REQ_HDRIFT: Maximum horizontal drift speed to use GPS, maximum is 1m/s

That would be less than the ship's speed, as long as it is travelling...

EKF2_GPS_CHECK: To switch on/off the different checks.

Does this only silent the "pre flight alerts" or would this really grant take off with "unlimited" GPS drift in Angle (Position) Mode?

I think you may be stuck with manual flight mode whilst on the ship.

That would also be my conclusion.
You could take off in Manual Mode and might switch to Angle Mode when safely clear of the ship. Switching "RTL" to the "GCS" setting (Ground Control Station) should let the copter fly to the last known position of the ST16 when the RC connection gets lost, but rember: the copter will land at the last received "GCS"-position (closer to you), but almost for sure not "anywhere safe" on the ship. At least chances are that when the drone gets closer to the ship a lost RC connection is more likely to get re-established.
It is a really challenging or maybe THE most demanding "location" I could imagine actually: a moving platform with steel, wind and water all around. (EDIT: not to forget the seagulls)

I know some folks that lost their fully functioning drones on that kind of occasion just due to the fact that the headwind made it impossible to return to the ship's deck - no chance also with all sport or manual modes in use... the battery drains at some point and a "safe ditching" gets inevitable.
So folks should always consider the winds and currents. I would only take that risk on smaller boats that could actually help "catching" the drone by respective maneuvers.
Big kudos from my side to everyone who takes this challenge in order to make great shots.
When I take shots where the drone not necessarily is about to return safely or could even not be recovered, I always use a new (empty) SD card in the camera and keep the done shots safe on other SDs or HDDs.

 

[Renier]

Hi Renier

The horizontal drift error message is new for most users since an update in January but more on that later.

Firstly have you calibrated all of the sensors?

Generally the bird needs to have the compass calibrated if the drone is more than 8 km (5mile) from where it was last calibrated. If you don't calibrated you run the risk of a flyaway.

The H520 will need to be calibrated HOWEVER the system is EXTREMELY sensitive to interference from lots of steel and iron. Owners manual advises no metal objects within 10 feet when calibrating. Your ship may make calibration impossible.

Takeoff in angle mode or using a Datapilot mission cannot occur without the GPS being properly calibrated. RTL is also problematic if the GPS hasn't been calibrated.

Flying manually (Atti mode for DJI folk) means that the drone will slide around a lot. Unfortunately I don't think it is possible to adjust the flight controller parameters to do what you want. I also think you would need to be able to adjust the parameters each flight as wind conditions will be different for each flight. Ultimately the biggest hurdle would be having a non-GPS reference that the flight controller and ST16 could recognise.

If you are able to successfully calibrate the bird I would strongly suggest that you set the Return Home Mode to RCS (Return to Control Station) before you do anything else. This is because you will be operating from a mobile platform. The normal RTL will send the drone to where the ship was when you started the flight.

Members are still working out all of the causes for the Horizontal Drift error message. It is commonly seen at startup and disappears quickly. My own experience is that it occurs with my machines when the drone is still initialising but the controller has got a 3D lock. It can also happen when the controller can see the sky but the drone can't.

I think you may be stuck with manual flight mode whilst on the ship. If you can get ashore at some point you can calibrate the drone and maybe get some good shots when the ship leaves the port.

Thank you for your reply, sorry for my late response. Our Internet onboard was very limited... as you said, I was stuck in manual mode and I was able to do calibrations without any issues.

I found a way to cheat the controller which worked well. After take off I was able to turn off indoor mode and switch to angle mode then and operate normally this way. However, to land I had to switch to manual mode, as the bird did not like the landing part with a forward motion in angle mode...

I am disappointed in yuneec, I have send several requests through their website and to date not a single responce from them...

 

[Renier]

I tr

As far as I know PX4 Autopilot has two parameter to control this behaviour in pre-flight checks.
EKF2_REQ_HDRIFT: Maximum horizontal drift speed to use GPS, maximum is 1m/s
EKF2_GPS_CHECK: To switch on/off the different checks.

Please be aware that it may be very dangerous to change the parameter because it may cause unexpected behaviour of the drone in different manners.

I do not know if H520 allows to access to those parameters.

Redirecting to latest version of document (main)

br HE

ied, but it does not accept the write command... So I guess we need root accsess to enable writing...

 

[Renier]

Somewhat familiar with this. I suggest after starting the H520 in normal mode you wait a bit. Touch the bird symbol at top and watch GPS Sat acquisition. I find after 15-16 Sats that the offending msg will go away.

If this does not work, you may be stuck with manual (non-GPS) operation. Also, be careful landing...
Good luck

That would be less than the ship's speed, as long as it is travelling...


Does this only silent the "pre flight alerts" or would this really grant take off with "unlimited" GPS drift in Angle (Position) Mode?


That would also be my conclusion.
You could take off in Manual Mode and might switch to Angle Mode when safely clear of the ship. Switching "RTL" to the "GCS" setting (Ground Control Station) should let the copter fly to the last known position of the ST16 when the RC connection gets lost, but rember: the copter will land at the last received "GCS"-position (closer to you), but almost for sure not "anywhere safe" on the ship. At least chances are that when the drone gets closer to the ship a lost RC connection is more likely to get re-established.
It is a really challenging or maybe THE most demanding "location" I could imagine actually: a moving platform with steel, wind and water all around. (EDIT: not to forget the seagulls)

I know some folks that lost their fully functioning drones on that kind of occasion just due to the fact that the headwind made it impossible to return to the ship's deck - no chance also with all sport or manual modes in use... the battery drains at some point and a "safe ditching" gets inevitable.
So folks should always consider the winds and currents. I would only take that risk on smaller boats that could actually help "catching" the drone by respective maneuvers.
Big kudos from my side to everyone who takes this challenge in order to make great shots.
When I take shots where the drone not necessarily is about to return safely or could even not be recovered, I always use a new (empty) SD card in the camera and keep the done shots safe on other SDs or HDDs.

Thank you for your thoughts and inputs... I never took of with a headwind more than 6m/s for the exact reason you described... After all I was able to fit in a few flights, but mostly the weather was terrible, lov visibility and we had mostly windy days in exess of 12m/s

 

[Gadget]

Glad to hear that you found a way to succeed.

Unfortunately Yuneec can sometimes be their own worst enemy.