Bitcraze Forums

Hi,

I am working on a project where I need to fly about 20 drones in formation. I am considering employing the Crazyflie 2.0 drones along with the Loco Positioning System for this purpose. Initially, I will be starting with 4 Crazyflies. As I understand, it is not possible to accurately locate a large of number of Crazyflies in two-way ranging mode since the update frequency will significantly drop. However, the TDoA does seem suitable for this application. Since it is listed as experimental on the Crazyflie blog in a post from a few months ago, I would like to know the current status of the firmware in terms of stability. Secondly, how well does the positioning system perform outdoors in terms of range? Lastly, is the Flow deck better suited to my application than the Loco Positioning System?

Thank you.

bump

Hi,
You are correct, TDoA is the way to go for a large number of drone. It is still considered experimental but the good thing with TDoA is that it will work the same way for 1 and for 20: you can start testing with a low number of Crazyflie. I am currently working on making a better TDoA anchor algorithm, I can keep this thread updated about it. The status of the existing algorithm is that it works but it does not react too well to UWB packet loss, this is what I am currently fixing.

The range will depend of the output power, we currently use the default output power and we get about 15m range with TWR, needs more test for TDoA. Increasing the radio output power is possible but it will require some measurement to make sure it is still bellow the regulatory limits of your country.

As for the flow, it does not provides absolute location but only a pretty good relative location (ie. velocity). It can be used together with the UWB LPS to achieve better flight performance. From the test we have done it is possible to fly in formation with the flow however it is not idea since it sometime drifts at startup and if so the full trajectory for this Crazyflie will be off.