About logdata and how to access actuator data during flight

PX4 Autopilot
1

Hello,
I woud like to use some actuator data while flying to evaluate a self written system equation.
Therefore I would need something like current rotor force/thrust/anything like that. I guess during Manual flight I would be able to track the thrust-rc-input for some calculations but what can I do during POSCTL or OFFBOARD mode…

So right now I’m using mavros, but it seems there is no direct ros topic about the actuator outputs. But there is something in the uLOGS which looks promising:
If I convert the logfile in a .csv I have acces to actuatoroutputs0 which list in my case entries for actuator 0 to actuator 5 (hexacopter) with entries like: 1314.0 , 1150.0 , 900.0

Can someone tell me what these numbers are? PWM Signals? RPMs? or something else?

And is there any possibility to access these outputs during a flight? Up to now I usually used rostopics, but I guess this won’t work now? Maybe it is possible to write some one plug in for a mavlink Code and start it via mavros … ???

Any help is appreciated. Thanks!

1 Like
2

Hello,

Did you figure out how to get rotor force/thrust?

Thanks

3

Hi @pmdoll,

to get the force/thrust would need some additional calculations depending on your actual motors.

But you can get the PWM Signals which px4 calculated via ROS and/or via the uLOG files.
ROS Topic mavros/rc/out
uLog actuator_outputs_0

Kind regards

4

Thank you @hsu-ret . I will look at ROS topics.

Best,