VOXL FPV ESC one motor not spinning

qubotics-admin

Hi,

I have the VOXL FPV ESC and I cannot spin/ calibrate one of the motors. 3 motors spin calibrate fine but one motor spins very intermittently. I tried replacing that motor but same behavior.

Screenshot of the ESC detection:

Good motor spin:
good spin.png

Bad motor spin:
bad spin.png

I think it is a bad ESC, but need your guidance if this can be fixed. The output when running this motor is different: it shows extra BOARD_VOLTAGE, and BOARD_CURRENT fields when spinning. Also it knows the RPM keeps going to zero.

Alex Kushleyev

Hi @qubotics-admin ,

Between the two tests, i see that one test shows 16V input voltage and the other test ~7.2V. Was the voltage applied to the ESC the same during the tests (and the ESC read it incorrectly) or the voltage was in fact different?

Such a big difference can have adverse affects on spin-up if the change in voltage is not accounted for in the esc tuning param file.

It is possible that if the ESC does not have correct parameters for your motor / propeller, the sinusoidal spinup does not have enough power and loses tracking during the spin-up phase and fails to transition to steady-state spin stage.

The ESC channel 2 on the FPV ESC is the only channel that measures the total board current, so that is why the printout is slightly different when you test the channel 2.

Please provide the following details that will help us figure out the issue:

what voltage are you testing the ESC? 16V or 7V?
what motor/propeller do you have and which ESC params are you using?
does the "bad" ESC channel ever properly spin up, or it never spins up at any battery voltage?
is this the first time you are using this motor + propeller + voltage combination with the FPV ESC , or it has been previously working reliably?
have you performed any ESC parameter tuning using voxl-esc tools?

Alex

qubotics-admin

@Alex-Kushleyev the tests were done all in succession with the same 4S (16V) battery. We are using Xing2 2205 2300kv motors with 5 inch props.

I followed the ESC calibration guide: https://gitlab.com/voxl-public/voxl-sdk/utilities/voxl-esc/-/blob/master/voxl-esc-tools/calibration.md

I started with this parameter file: lumenier_2305_2400kv_GF_D90_4S.xml and modified it as follows:
param name="vbat_nominal_mv" value="15200"
param name="num_cycles_per_rev" value="7"
param name="min_rpm" value="3200"
param name="max_rpm" value="25000"

Then I uploaded these, and did the calibration. I got good results initially, and all motors were spinning up fine.
param name="pwm_vs_rpm_curve_a0" value="29.00369359"
param name="pwm_vs_rpm_curve_a1" value="0.414700099"
param name="pwm_vs_rpm_curve_a2" value="3.58E-06"

Nothing else was changed in the parameter file, and it was uploaded to the ESC.

But while the drone was on bench, after 2 or 3 times of running, the motor on ESC channel 2 stopped spinning. I tried re-calibrating but now even during the calibration that ESC channel does not spin up the motor.

qubotics-admin

@Alex-Kushleyev

I tried spinning the motor (ESC ch. 2) with a fresh battery at 10% power. Now it shows 16V but still the same behavior.

I tried recalibrating, but it doesn't spin properly during calibration. Also, the end parameters are way off than the original ones (which are the same on the other 3 motors).