Homepage Knowledgebase GitHub

Tuning Questions

Hello, my team is getting into tuning our new Myxa ESCs. We had a few questions, and will probably have more in the future, so I thought I would ask them here. We are using these XOAR motors: https://www.xoarintl.com/brushless-electric-motors/titan-air/titan-air-TA60-light-weight-pro-series/#spec - the TA6012 130KV model. We are using Myxa for a multicopter. The configuration is a 12S battery (2x6S battery in series) and a 24 inch propeller. We are currently using the closed loop velocity control mode.

  1. There is a high pitched whining, especially at higher RPM. We are not sure if this is due to the thrust stand setup or the ESC itself.
  2. After usage, the motor is warm - not dangerously warm, but we were not sure if this was just due to usage or due to bad control tuning.
  3. Current draw reported by the ESC, especially at high RPMs, is higher (0.5-2A) than what is stated by the manufacturer. This is within a reasonable margin but we were wondering if this can be reduced somehow.
  4. Is there a graph in Kucher to display the RPM setpoint and actual RPM/other characteristics of the motor? That would help a lot with PID tuning of the controller.
  5. Myxa specification says it is rated for 51V (12S) but when we plugged in a fully charged set of batteries in series (2x6S), Myxa said the voltage was 50.4V (which is less than 51V) and warned that there was “DC overvolt.” This does not happen when the battery is slightly depleted.
  6. Was hoping you could provide some tips on both velocity loop PID tuning as well as spinup tuning. I have already read the getting started with Myxa forum article. We are making progress with the PID tuning, but it is still overshooting more than acceptable. The spinup tune is still very bad. In some configurations, the motor does not spin properly at all for a few seconds, then starts up. I tried the alternate configuration listed on the forum, but then the motor spasms fast for 3-5 seconds before settling down.

Additionally, I was wondering if Myxa supports (or will support in a future firmware version) UAVCAN/Serial over the USB port, for configuration and testing instead of PopCop.

Thank you for the help.

Hi Kalyan,

1, 2, 3. It might be due to improper motor identification or the speed loop tuning. Try to run the motor identification procedure once again. It’s recommended to carry out motor identification without a propeller.
4. No, Kucher doesn’t display plots. Please, use UAVCAN GUI Tool instead.
5. Myxa is rated for 51V indeed. But the warning appears at 50.4 V, because if the voltage is higher, there is a risk that the voltage will exceed the maximum allowable when the motor is decelerated quickly.
6. You can read more about the speed loop tuning in the instructions for tuning in the RPM control mode.
Try to increase the m.spup_curr_begn parameter for more reliable motor start. It increases the spinup motor torque.
Myxa doesn’t and won’t support UAVCAN over the USB. The main interface in Myxa and other Telega based ESCs is UAVCAN over CAN. USB is used just for quick setup.