Bitcraze Forums

Hi,

I am Agustín and in my research group we are testing swarm missions with LPS in TDoA2 mode and 8 anchors. Now, we are testing with 2 crazyflies 2.0 launching the dwm_loc_ekf_swarm_hover.launch commenting the part of the code related to the 3 last cfs (the launch by default is for 5 cfs).

Our problem is that sometimes we can do take off correctly, but in other occasions we can't do the take off with one of the cfs or even with both. In these cases, in the terminal appears the next error:

[WARN] [1551114664.980664]: Cannot set <=0 Z setpoint!
[WARN] [1551114664.985278]: Cannot set <=0 Z setpoint!
[WARN] [1551114665.014004]: Cannot set <=0 Z setpoint!
[WARN] [1551114665.018585]: Cannot set <=0 Z setpoint!
[WARN] [1551114665.047366]: Cannot set <=0 Z setpoint!
[WARN] [1551114665.052032]: Cannot set <=0 Z setpoint!
[ERROR] [1551114665.062750855]: client wants service /crazyflie1/takeoff to have md5sum d41d8cd98f00b204e9800998ecf8427e, but it has b665b6c83a196e4774268cc26329b159. Dropping connection.[WARN] [1551114664.980664]: Cannot set <=0 Z setpoint!

To do the take off we are using a joystick as follow: https://wiki.bitcraze.io/doc:lps:ros. To improve the Z estimation we are using the Z-ranger deck v2 too.

Does anyone have any idea about this?

Thanks so much in advanced.

For new projects I suggest using the Crazyswarm instead of lps-ros + crazyflie_ros (see https://crazyswarm.readthedocs.io/en/latest/). The Crazyswarm supports UWB with TDoA2 and TDoA3. You will benefit from having the actual position controller on-board for improved robustness.