As suggested in the MC Tuning Guide , I try to compensate thrust nonlinearities through the THR_MDL_FAC parameter, which is described as follows: THR_MDL_FAC (FLOAT) Thrust to PWM model parameter Comment: Parameter used to model the relationship between static thrust and motor input PWM. Model is…

That looks reasonable to me. 0.75 is a little higher than I’ve seen before, but not by much. If you find you have oscillations while spooling the props up before takeoff you can always drop it a little.

[image] Finwood: Do I assume correctly, that PWM in the model description above is normalized to [0…1] instead of [ PWM_MIN … PWM_MAX ]? Correct, that’s the case with the output curve function, the battery remaining calculations, the stick expo, they’re all [0,1] or [-1,1]. [image] Finwoo…

Thank you for your confirmation. The issue was already resolved in Slack, and the parameter documentation has been updated as well. [image] MaEtUgR: Your calculations and plot look fine, would give a good example in the documentation. Where in the documentation would you put an example like …

Where your first link to the docs is: https://docs.px4.io/master/en/config_mc/pid_tuning_guide_multicopter.html#thrust_curve It would be appreciated if you could add the example, the file can directly be edited here: https://github.com/PX4/px4_user_guide/blob/master/en/config_mc/pid_tuning_guide_m…

[image] MaEtUgR: It would be appreciated if you could add the example How about this? Provide THR_MDL_FAC Example PX4:master ← Finwood:provide-example-for-thrust-curve-linearization opened 05…

Perfect, thanks a lot for the contribution @Finwood !

Hello, To revive a bit this topic, I have a question. In near-hovering the relation between the propeller speed V and thrust provided by the blade is T = kt * V² with kt the thrust gain. And the input signal to the motor 0-1 should be proportional to the speed of the blade (I am talking DSHOT pr…

Thrust Curve Compensation through THR_MDL_FAC

PX4 Autopilot

Finwood October 14, 2019, 7:01am 4

Thank you for your confirmation. The issue was already resolved in Slack, and the parameter documentation has been updated as well.

Where in the documentation would you put an example like this?

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Thrust Curve Compensation through THR_MDL_FAC

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