Sapog motor spinup issue

Support Sapog motor control
1

Hi,

The setup I’m current running is the following:

Axis 2814/20 v2
Holybro Kotlela20 / sapog 2.3.fa0ff46
on a 3s lipo @ 12.4V

I’m having issues with the motor spinup where the motor will jerk for about 1sec before spinning normally. This appends only at start, the motor as no problem spinning smoothly at low speed.

what would be the procedure to tune the ESC for a smooth spin up?
Is there any way to debug this with logs?
Also do you need to restart the node for parameters changes to take effect?

Thanks

2

Yes, this is explained in section 5.3 Configuration parameter index.

Have you tried the suggestions given in section 7.2.3 Low-speed operation? They apply not only to the continuous low-speed operation, but also to the spin-up process.

3

Thanks for the quick reply,

I’ve set the mot_v_spinup to 2,5 and the mot_spup_blnk_pm at 50, and it seems to prevent “false” starts. The start up is still not as smooth as on commercial ESC. I’ve also notice that we the esc tries to play a sound, it’s not very crisp, maybe it’s a indication of some other parameters to be tuned? Do you have any tip on how to tune the esc properly to a motor? Can I use the motor specifications to get a better initiate guess of the correct parameters?

I’ve got a t 840Kv 14 pole motor on a 3s system so I know the max mechanical RMP wont be over 10584 (7758 rad/s electrical) and since I’m on 18650 cell going down to 2.5v the min RMP will be somewhere under 6300 (4618 rad/s electrical). Shoudn’t the lowest RMP give me a idea of the mot_comm_per_max?

Am I doing the mechanical to electrical conversion right? I’ve tried using these value to set the mot_pwm_hz parameter but couldn’t get a full duty cycle (power_rating_pct = 100) unless I set it to 70000Hz and above which doesn’t match Figure 2.10.

A thought:
I’ve got the Myxa esc could it be used to identify the motor parameter to be used with the sapog. I would use the Myxa directly but my application use at most 3s batteries.

Thanks

4

At the moment it is not possible to derive optimal configuration from known motor parameters, so the best advice I can provide is to apply systematic trial-and-error to find the configuration that works in your case.