We have recently developed and tested a formation control algorithm for fixed-wings in Paparazzi. The position of an arbitrary number of vehicles can be controlled in a circular path. In fact, we are not restricting ourselves to circles but to any closed orbit, such as ellipses, thanks to the guidance vector field that guides the planes.
The algorithm is under more tests, but it should be soon available for the general public. It is quite easy to employ, the user has to declare only the IDs of the planes, the communication topology (neighbors' relationships) and the desired inter-angles.
In the following video the planes exchange positions every second. Delays, out-of-date positions (GPS delays), packet losses, etc are expected to be (and actually they are) present. It is quite interesting to remark how robust the algorithm is. According to our calculations the impact of such nasty things are not very important (ofc up to a certain point) for the convergence of the algorithm.
The work will be submitted to the next IROS conference. Once the paper is ready, I will also post it here just in case somebody is curious about the details.
Comments
thanks guys!
@Eric, we are at ENAC, Toulouse.
Awesome, well done!
Congratulations, for this work, where are you in France?
Great job, congratulations.
Hi Marc,
thanks!
It is totally possible to set different bearings/distances and we have already tested it too (always following a closed orbit such as circular paths). In this video the rendezvous was for "aesthetic" purposes :P.
The information that we are exchanging now is the absolute position from the GPS, but the algorithm should also work with relative positions (if you have a sensor that is capable of measuring it).
Right know in Paparazzi, all the communications have to go through a central server (most likely at ground). However, to have a "secondary" network for inter-vehicle comms is possible, e.g., via Xbee or Decawave radios. For an specific application it is not a big deal to implement it, but still it is not an elegant solution.
It is in the roadmap of Paparazzi to evolve the current communication system to allow inter-vehicle messages. Whereas to have direct communication among vehicles is a trivial task (technologically speaking), developers are still thinking an appropriate way of how to do it in order to have a good integration/impact, etc. Let us see :P.
Impressive work. Is this being directed by the GCS or are the planes communicating directly?
On a related matter, it would be nice to have the ability of on UAV to follow another at a consistent distance and bearing. It is very common for multiple panes to fly FPV formations. I notice that autopilots like Pitlab have UAV-to-UAV communication to facilitate this. In the case of Pitlab I think it just gives an OSD bearing to your friend.