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Tuning prop loads with rapid erpm increase in duty cycle or speed control

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mirage98
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Joined: 2022-09-10 16:41
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Tuning prop loads with rapid erpm increase in duty cycle or speed control

I'm curious if someone has guidance and/or tuning tips for utilizing vESC in a propeller load (fixed-wing) scenario with duty cycle or speed/rpm control and FOC motor control.  The biggest issue I'm experiencing is a lock-up and stutter/screech when increasing input via speed or rpm control (using UAVCAN input) fast from a 0 ERPM start.  Once the propeller is spinn, say ~5000 erpm, then rapid increases are a non-issue.  I'm assuming what I'm experiencing is the observer losing tracking because the motor can ramp fairly quickly without a constant load (prop vs surface).  I've done some initial tuning and have made it significantly better, but I still don't have trust in this vs a traditional non-FOC duty cycle ESC.

Question 1) What are the most important settings to tune first (assume motor values) and how to verify they are dialed in?
What I've done:  Followed the BV's videos and tuned using current mode.  Current is stable and smooth, no problems here.

Question 2) What are the best settings to tune for initial / low speed ramp.
What I've done:  Tweaked various openloop settings, didn't really make a difference.  Adjusted tuning frequency, some improvements, best improvement with V0/V7 on.  Setting that has helped the most is startup eRPM current limits.  This works decently well on cold motor, but once warmed/saturated, then the motor gets "sticky" during a fast ramp (cog/stutter for 1-2 seconds and then finally go to input speed and behave normally).

Question 3). What are some specific settings for speed control to help with the above?  Looks like there are no options to tune duty cycle unless you're PPM control.

I've dug through the forum and various other online resources, but duty cycle (and some extent speed control) tends to be considered problematic (or more difficult to tune) and the answer is current control.  Also, most guidance on tuning is based on skateboard, which doesn't have this 0 load and load increase with RPM that a propeller has.

Any guidance is appreciated.

drummerboy5408
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Last seen: 4 months 2 weeks ago
Joined: 2019-05-26 22:42
Posts: 24

Are you using ArduPilot and UAVCAN?

Also, Use Duty Cycle control instead of Speed control. It eliminates 1 set of PIDs making it easier to tune