Bypass 8m height Limit with No GPS?

[Cw4bray]

Did you find a workaround / fix?

Yes and No, I moved outdoors so I could "see" sky. ... Sorry .... How about a few D-gps transmitters ?
Differential GPS - Wikipedia
Another (different) problem I've had; while installing a HF antenna in a tree. My MM just started climbing uncontrolled. I had the remote cargo release hook tied to a string about one meter long, I thought it was long enough for the sensor, it must have been 6" too short. The sensor "saw" the cargo hook and tried to climb away from it. It got up to 30' before I got it under control and in landing mode by holding the stick down. The solution was to mount the release hook on top of the fuselage, so it's away from the sensor.

 

[scro]

For education: D-GPS transmitters only send out a realtime correction factor to be applied to standard GPS signals local to it, not a pseudo GPS signal. That correction factor can then only be used by other GPS equipment capable of receiving and applying the correction. If the drone can't receive a native GPS signal, having a D-GPS transmitter won't help.

The Wikipedia page linked to explains how D-GPS works. Essentially a stationary, fixed base station records the jitter of the GPS signal and this jitter info is sent out to the field GPS device. The field GPS device then subtracts the jitter from its solution for its position.

 

[ff22]

Normally we carry out industrial inspections with Flyability ELIOS drones.

This time we fly underground in a salt mine (0% humidity).
Everything that comes in contact with normal air on the surface of the earth will be destroyed very quickly.
Unless we lose the drones, they will remain in the mine for future missions.

Therefore we cannot use our Flyability ELIOS drones and have bought two DJI Mavic Mini and are currently working on the modifications (very light cage, bright LED light powered by the flight battery).

Heavier drones are out of the question due to the dusty environment (more thrust).
(Technically speaking, a Phantom 4 would be perfect, but it is too heavy and probably raises too much dust.)

We also generally assume that the drone will eventually lose it, so we let a screen recorder run along.

If all of the video is not entirely proprietary, it would be wonderful to see some of the footage. Sounds absolutely fascinating.

 

[EyesWideShut]

... "and I use 24v high power led (with a tiny dc booster) on the front and the bottom of the drone" ...

Hi again. I'm interested in your 24v LED with a dc-dc booster running off the mini's 7.2v battery. Can you provide any info and/or links to the LED and booster you are using?

Thanks for your time and we hope to hear more about your project.

 

[Kristof.Bremen]

Yes and No, I moved outdoors so I could "see" sky. ... Sorry .... How about a few D-gps transmitters ?
Differential GPS - Wikipedia
Another (different) problem I've had; while installing a HF antenna in a tree. My MM just started climbing uncontrolled. I had the remote cargo release hook tied to a string about one meter long, I thought it was long enough for the sensor, it must have been 6" too short. The sensor "saw" the cargo hook and tried to climb away from it. It got up to 30' before I got it under control and in landing mode by holding the stick down. The solution was to mount the release hook on top of the fuselage, so it's away from the sensor.

Very interesting!

 

[Kristof.Bremen]

If all of the video is not entirely proprietary, it would be wonderful to see some of the footage. Sounds absolutely fascinating.

I think it will be proprietary ... but let's wait and see

 

[Kristof.Bremen]

The flight went extremely well!
We have not lost a drone.

But if you sink below the initial altitude, the Mavic Mini will attempt a landing. We then let the Mini sink another 30 feet and put it back on full throttle. The Mini then stops descending at this altitude and you can continue the inspection.

Unfortunately, once you are on the ground (about -60 feet) you cannot fly back up.

But somebody could recover the Mini.

Even in bad light the pictures are excellent. I am currently creating a 3D model from the single photos with Pix4d.

Currently we are not allowed to publish any pictures, but we will talk to the customer today and then we will see what happens.

 

[scro]

Good to hear your inspection went well, and thanks for letting us know!!

Interesting to hear it wanted to land if you went below the takeoff altitude. I wonder if that is the same mechanism kicking in that some people have had occur when flying low over water? It doesn't auto land if it has GPS and you go lower than takeoff point. Were you only able to stop descent, and not gain altitude when auto-landing was active? Once landed on the ground were you able to take off again?

 

[BokiFly]

I wonder if that is the same mechanism kicking in that some people have had occur when flying low over water? It doesn't auto land if it has GPS and you go lower than takeoff point.

If it doesn't auto land if it has GPS then why it tries to land when low over water?

Unfortunately, once you are on the ground (about -60 feet) you cannot fly back up.

Interesting. It can't even take off?

 

[scro]

If it doesn't auto land if it has GPS then why it tries to land when low over water?

I don't know why, in some circumstances, the drone tries to land when flying low over water. I've not yet discovered a logical explanation, and I've not had it happen to me yet. Kristof's observation that the drone tries to autoland when below the launch altitude, and with no GPS, may be linked to the water landings some have had. Perhaps they didn't have GPS lock at the time? I've not seen the flight logs nor experienced it myself so it's just conjecture.

 

[Kristof.Bremen]

I don't know why, in some circumstances, the drone tries to land when flying low over water. I've not yet discovered a logical explanation, and I've not had it happen to me yet. Kristof's observation that the drone tries to autoland when below the launch altitude, and with no GPS, may be linked to the water landings some have had. Perhaps they didn't have GPS lock at the time? I've not seen the flight logs nor experienced it myself so it's just conjecture.

I think it has to do with the fact that the infrared sensors are not able to detect the correct height because of the reflection!

 

[Kristof.Bremen]

Good to hear your inspection went well, and thanks for letting us know!!

Interesting to hear it wanted to land if you went below the takeoff altitude. I wonder if that is the same mechanism kicking in that some people have had occur when flying low over water? It doesn't auto land if it has GPS and you go lower than takeoff point. Were you only able to stop descent, and not gain altitude when auto-landing was active? Once landed on the ground were you able to take off again?

we were also able to process some photos in pix4d.

does anyone know if the mavic pro 2 flies higher than 5 meters / 15 feet in atti mode?

 

[Keule]

does anyone know if the mavic pro 2 flies higher than 5 meters / 15 feet in atti mode?

Can't speak for the M2P, but the M2E/M2ED is able to fly up to 60m in ATTI mode.

 

[EyesWideShut]

The flight went extremely well!
We have not lost a drone.

But if you sink below the initial altitude, the Mavic Mini will attempt a landing. We then let the Mini sink another 30 feet and put it back on full throttle. The Mini then stops descending at this altitude and you can continue the inspection.

Unfortunately, once you are on the ground (about -60 feet) you cannot fly back up.

But somebody could recover the Mini.

Even in bad light the pictures are excellent. I am currently creating a 3D model from the single photos with Pix4d.

Currently we are not allowed to publish any pictures, but we will talk to the customer today and then we will see what happens.

Congratulations on getting the job done!

Wondering about the descending and being unable to takeoff after landing on the floor. As you previous said there is no gps underground but were you using both the bottom sensors, visual and proximity, or did you cover either up with tape and fly in ATTI mode?

EDIT: I see you've since posted that you think the reflections may be the culprit. Maybe taping the sensors and fly in ATTI would be the fix, but a little difference in handling.

Thanks for the PM reply about the step up converters, could you share a link on the 24v leds you are using for forward and downward illumination and are you using one or two. Thanks!

 

[scro]

I think it has to do with the fact that the infrared sensors are not able to detect the correct height because of the reflection!

Undoubtedly it does, but it's not clear why this would trigger an auto-land command in some circumstances. ?

Typically the reaction of the drone is to either do nothing if it is too high for VPS to detect altitude, or gain altitude if VPS thinks it is too close to the ground.

If you take off from a table inside (ie no GPS) and fly forwards and down towards the floor does the MM try to automatically land, when it registers "negative" altitude? I'd try myself but my MM is currently arboreally parked?