Indoor positioning system for drone shows and swarms

Summary

Indoor positioning system for drone shows and swarms.

Examples

Task

To provide precise indoor positioning coordinates for drone swarms and drone shows.

Problem

The key difference between an indoor positioning systems for a drone scanning objects in a warehouse, for example, and an indoor positioning system for  an indoor drone show or an indoor drone swarm research project is the number of drones involved.

To track one or two drones is not a problem because multiple options are possible: NIA, MF, NIA, IA. See more: basic comparison of system architectures.

But for drone swarms consisting of 8-16 drones, only MF NIA and IA are suitable in practice. With the number of mobile objects (drones) more than that, only IA is a viable option. It happens because NIA is using the TDMA approach, and the location update rate per drone for 16 drones would be only 1/16th of the location update rate per system. With a typical location update rate of 8-16Hz, the location update rate per drone would be only 0.5-1Hz, which is very low.

With IA, the location update rate per drone doesn’t directly depend on the number of drones. It can be 8-20 Hz/drone depending on the size of submap and other settings.

Solution

The precise indoor positioning solution for indoor drone shows and swarms is a combination of proven solutions:

Previously, we always guided against using IA with drones, because the propellers’ noise would severely limit the range of the IA system. In IA system, mobile beacons are listening to the ultrasound pulses of the stationary beacons. Since, stationary beacons are far and their signal is weak, the propellers’ noise would simple mask the ultrasound signal from the stationary beacons and break the system.

However, a combination of technical solutions, such as using sharp DSP filters, placing the microphone above the propellers, and hiding the microphone behind a special ultrasound deflector, helps to overcome such a limitation. These are the know-how that we introduce with this new solution.

See the photos on the left for more details. Notice the external microphone, microphone pole, and microphone deflector. Stationary beacons must always be above the drone in this configuration.

Recommended configuration

Notes

Direction

Power supply to Mini-RX

Power supply to stationary Super-Beacons

Comparison with NIA and MF NIA

Skill requirements

Drones with propellers facing down

Some drones have propellers facing down and the drones are relatively large. This creates an opportunity to install Super-Beacons in the Paired Beacon configurations right above drones – similar to the RTK GPS antennas that can be seen.

  • The beacon’s body will create a natural ultrasound deflector for the noise of propellers and motors so that no additional ultrasound deflectors are required
  • It is a theoretical note and a recommended solution and it is a subject of practical testing to learn the maximum distance the IA will still work well. Because there is certainly a distance when the signal/noise ratio will drop below a limit and the tracking won’t be reliable anymore. The testing is quick and straightforward, with the help of an Oscilloscope embedded into the Dashboard. You will literally see in the Oscilloscope the noise of the propellers after all the shielding and filtering, as well as the ultrasound signal from the stationary beacons. It takes minutes to perform such verification tests
A drone with propellers facing down
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