Thrust tests: Motor Thrust Scaling in Motor Tests? In Motor Tests: CTUN.ThO == Throttle?

ArduCopter
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1

Hi everyone!

I want to determine the function that describes what thrust is produced at which throttle, for my particular UAV.
Therefore I set the UAV to perform a certain throttle, and measure the thrust it produces. For now, I used the Motor Test of MissionPlanner. The curve I got so far is highly non-linear (regression: thrust / N = 0.001032 * (throttle / 100%)^2.302). As motor thrust scaling (https://ardupilot.org/copter/docs/motor-thrust-scaling.html#motor-thrust-scaling) is performed with MOT_THST_EXPO == 0.5, my gut tells me the curve should not be that non-linear. So my first question is:

  1. If MissionPlanner’s Motor Test routine is performed, does ArduCopter apply Motor Thrust Scaling?

An alternative approach would be to arm the UAV and put it into STABILIZE mode. Then I would slowly increase the throttle and measure it.
Hence my other two questions:

  1. Is there a way to immediately show the actual throttle value at MissionPlanner’s HUD?
  2. Is the log entry CTUN.ThO the throttle value I’m looking for (the value after motor thrust scaling)?

Yours,
Peter

PS: I have a quadcopter (X-configuration), ArduCopter 3.6.11, MissionPlanner 1.3.68

2

Here is a graph of my existing test data. Perhaps this is a bit more demonstrative, than the formula alone :wink: The blue values (label “FALSE”) are the relevant ones.

image

3

Hi there @peterst
I know it’s been year ago, but I’ve found your post asking whether CTUN-tho is the throttle value in Misson Planer, did you have any luck solving this issue?

4

I am wondering if this Motor Scaling is still relevant where I have not seen a small-size motor that can fulfil the idea. I tried and notice only industrial-grade motors can manage to fulfil it, such as T-Motor U10II, Hobbywing X6rotor, etc.