Knowing How To Fly In ATTI Mode Might Save Your Drone

[CP Anson]

This is an article that I wrote for Photofocus.com on how ATTI mode helped me. I am sharing this in hopes that it will help others.

Photofocus | Knowing How To Fly In ATTI Mode Might Save Your Drone

Chris

 

[Florida Drone Supply]

This is an article that I wrote for Photofocus.com on how ATTI mode helped me. I am sharing this in hopes that it will help others.

Photofocus | Knowing How To Fly In ATTI Mode Might Save Your Drone

Chris

Thanks for the link, this is helpful.

 

[The Editor]

Since this is not I2 specific, moved to General discussion.

It should also be noted that metal structures do not affect GPS reception (unless they are tall structures obscuring unobstructed views above the horizon and thus decreasing the precision) and losing GPS will have no affect on the aircraft's ability to maintain stable height since this is dependent on the internal barometer which has a resolution of around 10cm.
Additionally, Atti mode is not DJI aircraft specific since other manufacturers Flight Controllers can be switched to this mode.

 

[CP Anson]

Since this is not I2 specific, moved to General discussion.

It should also be noted that metal structures do not affect GPS reception (unless they are tall structures obscuring unobstructed views above the horizon and thus decreasing the precision) and losing GPS will have no affect on the aircraft's ability to maintain stable height since this is dependent on the internal barometer which has a resolution of around 10cm.
Additionally, Atti mode is not DJI aircraft specific since other manufacturers Flight Controllers can be switched to this mode.

I would really like to understand better what is happening and it sounds like you may be able to help with that if you would. So if large metal structures don't impact GPS reception unless obstructing views then what is the likely cause of the GPS interruptions that I was having in the following circumstances.

When flying within about 200 feet of the large bridge and above eye level with the bridge, I lost GPS connection and when I flew away from the bridge about 100 feet, GPS returned. I was not in the shadow of the bridge. In this case I also had the drone lose its horizontal stability and start to tilt to one side.

When I was setting up a launch location and was on large concrete and metal pilings about 800 feet from the bridge, I was able to connect but was not able to get a stable GPS lock until I was 25-30 feet above and away from the platform.

On a construction shoot last week, I was near piles of unused rebar and about 100 yards from a 20 story building under construction. On takeoff I immediately lost GPS and had to switch to ATTI mode. When I climbed to about 25 feet, I was able to switch back to GPS mode and got a strong lock. I also found on the ground, to get a consistant connection with my remote to the drone, I needed to move further away from the piles of steel or I would get an intermittent connection.

I would appreciate any insights you might have in helping me understand more about what is going on in these situations.

Thanks, Chris

 

[NickU]

Out of interest, did you do any kind of calibration (IMU/compass) before flying at those locations?

 

[CP Anson]

Out of interest, did you do any kind of calibration (IMU/compass) before flying at those locations?

The day before each flight I checked my IMU and compass settings at a location free of any kind of interference and they were both in the excellent range. I had been flying a number of days that week at different locations within about 20 miles of these and did not experience any issues.

 

[NickU]

glad to hear you didn't do any cals onsite as they can cause a lot of problems with the compass, which in turn can confuse the heck out of the aircraft when it tries to tie it in with the GPS signal it's getting.

The presence of metal itself wouldn't cause gps signal loss, but you depending on the number and position of the satellites you might have encountered some gps multipath/reflection caused by the water and/or the tall structures reflecting or refracting the satellite signals. If part of the satellite constellation was out of use or a number of satellites where close to the horizon with fewer higher/overhead then again signal could be degraded. Couple that with some minor magnetic disturbance from the iron if flying nearby and the flight controller might have had a headache deciding what was going on.

Could be that you return to fly in same location and don't have any repeat issues on a different day.

 

[CP Anson]

glad to hear you didn't do any cals onsite as they can cause a lot of problems with the compass, which in turn can confuse the heck out of the aircraft when it tries to tie it in with the GPS signal it's getting.

The presence of metal itself wouldn't cause gps signal loss, but you depending on the number and position of the satellites you might have encountered some gps multipath/reflection caused by the water and/or the tall structures reflecting or refracting the satellite signals. If part of the satellite constellation was out of use or a number of satellites where close to the horizon with fewer higher/overhead then again signal could be degraded. Couple that with some minor magnetic disturbance from the iron if flying nearby and the flight controller might have had a headache deciding what was going on.

Could be that you return to fly in same location and don't have any repeat issues on a different day.

Thanks for the insights. I learned early on to not recalibrate unless I see a problem in the sensors. I have a couple of locations where I do my recalibration that are clear of any interference.

It is interesting that the construction location that I shot at last week was very close to the bridge structure where I had similar issues.
In regards to your comment about water and iron nearby the bridge, yes lots of iron in the bridge, lots of iron in the takeoff/landing area and it was always over water. The construction site was just lots of iron.

When I get a chance I will return to the same location and see what interference I get.

 

[ReadyKilowatt]

For some real white knuckle flying pick up a 3dr Solo and put it in "sport" mode. After that experience ATTI was a piece of cake!

 

[Steve@AerialImagesPro]

metal affects the compass and will make your drone drift a lot. But it won't have any affect on GPS, unless, like Editor said, it gets between you and satellite. That's highly unlikely though unless you had less than 5 or 6 satellite lock. Which is why you always want at least 7 satellite lock when flying.

AND the moral of the story is what I tell people all the time and, in my opinion, is the biggest reason for drone crashes. Because many people have no idea how to fly without automation and when something like that happens they usually crash.