Back from ICRA 2019

3 of us where at ICRA 2019 in Montreal last week, where we met a lot of interesting people and a lot of Crazyflie users. Thanks a lot to everyone that drop by our booth, and for the ones that missed it we are planning on being at iROS2019 later this year so we might see you there :-).

We have already described our demo in a previous post, now that we run it we can update on how it went. We are also updating the ICRA2019 page with the latest source code and information so that anyone interested can reproduce the demo.

In its final state at the conference, the demo contained 8 Crazyflies 2.1 equiped with Lighthouse deck and Qi charger deck. There were 8 3D-printed charging pads on the floor with Ikea Qi wireless chargers and two HTC Vive base stations (V1) on tripods. The full system was contained in a cage, built from 50 cm-long tubes or aluminium and nets.

The full setup of the booth took us about 4 hours, this included about 3 hours for the cage, 15 min for the demo including calibration of the lighthouse base-station geometry and the rest to fine-tune things. This is by far our best setup time, we still need to prettify the cage a bit and to make is easier to install, but we will most likely re-use this system for upcoming conferences.

In this demo we aimed at keeping a Crazyflie in the air at every moment, to do so we had a computer connected to all 8 Crazyflies sending to one of them the signal to start flying if no other where actually in the air flying a trajectory. The flight was completly autonomous as we explained in our previous blog post. We setup the Crazyflie to fly 2 cycles and then land, which increase the rate of swap and so increased the ‘action’, though it also meant that during the swap two Crazyflies where flying. This drained the batteries a bit more than expected and meant that after about an hour all the Crazyflies where bellow the take-off threshold and we had to wait ~30 seconds between flights. Here is a video of it in action:

The demo was very care-free, we had very few Crashes and we mostly restarted the Crazyflies to swap batteries manually to add a bit of power in the swarm. The last day we decided to spice it up a little bit by adding a chair in the cage and by calibrating the chair position and flight trajectory, we managed to have the Crazyflie partly fly under it. This worked quite well most of the time and showed that the lighthouse positioning is repeatable and works fairly well with short occlusion in the path. Though we also found out that even though a single Crazyflie would always fly the same trajectory, two different Crazyflies will not. We think differences in propeller stiffness and the fact that the our Mellinger position controller has not been calibrated for changing YAW are the main reasons.

If you want to know more about the demo or if you want to reproduce it do not hesitate to visit the ICRA 2019 page that explains it in more details and links to the source code of everything including 3D printed parts for the cage and the landing pads.

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