Flying the Mini 4 Pro Indoors - ATTI Mode or Other Tips?

[Dogpilot]

All I can say is my system works quite well. I actually own and use one, I do not depend just on the web, but actual experience. I have been using it since 2017, now with several generations of drones. Notice even your quote says usually. If it was using only the VPS it would tend to drift , since the carpet provides little texture data. I have tried testing my drones during the winter indoors. The 2-3' of snow pretty much eliminates any GPS signal. When the drones try flying just by VPS they drift and do not maintain a steady hover, at least in my home with the very neutral beige carpet. Being a geologist I have a lot of survey equipment, some ground based some airborne. I Also own a D-RTK-2 system for the enterprise drones and a Emild Rover for field ground truthing. I am pretty up on casting gps data.

 

[Meta4]

All I can say is my system works quite well. ...

It will be interesting get confirmation of whether the handheld shows different coordinates as you move around.
I can't see how it could and believe that the repeater could only relay the coordinates of its outdoor location, which makes me wonder what the purpose of such a device would be.

 

[GadgetGuy]

All I can say is my system works quite well. I actually own and use one, I do not depend just on the web, but actual experience. I have been using it since 2017, now with several generations of drones. Notice even your quote says usually. If it was using only the VPS it would tend to drift , since the carpet provides little texture data. I have tried testing my drones during the winter indoors. The 2-3' of snow pretty much eliminates any GPS signal. When the drones try flying just by VPS they drift and do not maintain a steady hover, at least in my home with the very neutral beige carpet. Being a geologist I have a lot of survey equipment, some ground based some airborne. I Also own a D-RTK-2 system for the enterprise drones and a Emild Rover for field ground truthing. I am pretty up on casting gps data.

Please turn all the lights off, and repeat your flight in complete darkness, and report back, while checking the handheld GPS coordinates during the flight.

Your repeater can only relay the coordinates of the external GPS antenna, which is only designed to simulate a single GPS signal location for testing purposes of avionics indoors, and is not designed for navigation indoors.

I am not disputing your ability to fly indoors without GPS. DJI drones do quite well without GPS indoors in well-lit areas within 30 feet of the ground.

However, they cannot fly well in the dark without also receiving GPS. A repeater will only transmit the location of the external antenna, which will not help with supplying the necessary changing GPS coordinates of the drone inside for GPS navigation.

 

[Zbip57]

I did wonder about how the drone calculated it's local position in relation to the relay... was thinking in terms of one of the RTK rover units, which I guess might be a viable option with one of the RTK-enabled drones. Thanks for the clarification.

RTK-enabled rovers need simultaneous GPS reception at both the RTK antenna and the rover.

I'm thinking of buying a robot lawnmower and wondered how they can assure cm precision navigation of the robot to avoid mowing down my wife's flower garden, when GPS is typically never that precisely accurate. So I did some research to learn how RTK gps works.

The trick is that the RTK antenna is in a fixed location and therefor knows by how much to correct for drifting positional signal resolution. It constantly transmits that correction factor to the rover, so it can similarly correct the signal received by the rover from that same GPS satellite. But it requires the rover and RTK antenna to both be able to see the same satellite.

Here's a long, but really good, video describing how it works.

To view this content we will need your consent to set third party cookies.
For more detailed information, see our cookies page.

Accept third party cookies

 

[GadgetGuy]

RTK-enabled rovers need simultaneous GPS reception at both the RTK antenna and the rover.

I'm thinking of buying a robot lawnmower and wondered how they can assure cm precision navigation of the robot to avoid mowing down my wife's flower garden, when GPS is typically never that precisely accurate. So I did some research to learn how RTK gps works.

The trick is that the RTK antenna is in a fixed location and therefor knows by how much to correct for drifting positional signal resolution. It constantly transmits that correction factor to the rover, so it can similarly correct the signal received by the rover from that same GPS satellite. But it requires the rover and RTK antenna to both be able to see the same satellite.

Here's a long, but really good, video describing how it works.

To view this content we will need your consent to set third party cookies.
For more detailed information, see our cookies page.

Accept third party cookies

So the same would be true without RTK. In order to navigate without VPS in the dark, if a GPS repeater is active, one would also have to have GPS reception on the drone itself, or be using VPS with sufficient lighting where the GPS repeater is not being used at all. In other words, in complete darkness, where VPS cannot help, a GPS repeater cannot help with drone navigation.

The easiest way to confirm this is to fly indoors in complete darkness with a GPS repeater active, where VPS cannot be used. The GPS repeater coordinates do not change, and unless GPS is independently also being received by the drone indoors, the drone cannot maintain position via GPS nor be navigated using only GPS.

Anyone able to test this? ;-)