Indoor positioning system for drone competition​

Indoor positioning system for drone competition

We received a request from one of the aspiring teams for the Singapore Amazing Flying Competition (SAFMC) 2024. We have received similar requests in the past for other drone competitions. Thus, it is time to explain how to build indoor positioning systems for such cases in detail.

Basic intro to be on the same page:

Drone competition map

SAFMC 2024 drone competition map

The key requirement

  • To be tracked, the mobile beacon on the drone must have a direct line of sight to 3 or more stationary beacons within 30 meters
The requirement above is THE key requirement.
Since, typically, the rooms are smaller than 30 meters, the key requirement is to have a direct line of sight between the mobile beacon(s) on the drone and serving them stationary beacons.

Other requirements and recommendations

Other requirements depend on the required accuracy and the shape of the area. More beacons will be required if the area has narrow corridors or complex obstructions. A large but open area will require fewer beacons because the line of sight is THE requirement. Providing it for the complex area with more obstructions is more difficult.
Back to the geometry. For example, if you have a 20-meter narrow corridor, you typically can’t place just two beacons at the ends, because the trilateration will have acute angles and the tracking accuracy will suffer in one of the dimensions:

Similar limitation when you have a too small base between the stationary beacons:

Or when you want to land:

Placement of beacons

As soon as the requirements for the system to work properly are understood well, placement of beacons is rather a trivial task. One must place them so that the requirements are placed with the minimal number of beacons

Thus, it is recommended configuration is to place 27 stationary beacons at the locations marked by orange points:

Time to deploy

It takes a couple of minutes to place and deploy a basic map of 4 stationary beacons in one room and to have precise tracking. No distance measurement is required. Everything is automatic and takes seconds

However, when you have multiple submaps, like in the competition case, stitching different 3D submaps with smooth handover between them may easily take days – depending on the team’s experience.

Placement of beacons, submaps, and maps:


The task to fly autonomously in the environment shown on the map is not a trivial task and requires skills and understanding of the positioning technology, geometry, and drones. But it is doable. It is doable for the competition and real-world cases as well.

July 2024
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