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Is there a way for me to see the motors RPM (angular speed) in flight logs?

Posted by Ari Schwartz on November 19, 2017 at 8:01am

Hi!

I was wondering if there is a way for me to see the RPM (angular speed) of each of my motors in the flight logs?

Thank you very much! Any insight will be deeply appreciated!

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Tags: angular, logs, mission, motors, planner, propellers, quadcopter, quadrotor, rpm, speed
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Replies

  • Andre K. November 22, 2017 at 11:59am

    During the flight you can see the SERVO_OUTPUT_RAW mavlink message.

  • Ari Schwartz November 22, 2017 at 11:50am

    Thanks Andre!

    I was wondering if there is a way for me to see flight logs live during a flight. I would like to see how much PWM each motor is getting during real time.

  • Andre K. November 20, 2017 at 12:34am

    As long PWM range is calibrated (and does not "learn" new max along the way)  - it is kind of proportional to the RPM, - with the exception of voltage drops, and PWM changes instantly, while actual RPM takes some time..

    *sensed* RPM/power is a better way to detect minor problems and diagnostic use.  once, when the AP is aware of RPM & Current of each ESC, we will be able to detect all kinds or problems including disintegrated propeller.

  • Ari Schwartz November 20, 2017 at 12:27am

    Thanks for the response, Andre!

    Sorry for not mentioning, yes I am referring to a quadrotor.

    Is it true that the PWM (which can be seen as RCOU in the flight logs on Mission Planner) is proportional to the angular velocity? So theoretically I would just need to find the constant that relates the PWM to the angular velocity?

    Thanks again!

  • Andre K. November 20, 2017 at 12:19am

    Assuming you mean multirotor:

    no, once UAV-CAN ESC's are common, this should be in place, PWM controlled ESC have simplex communication only. 

    On any case, you can add electronics that communicate over mavlink with GCS, and/or CAN/I2C with autopilot and monitor any/all motors if you want, but it requires some electronics and programming skills.

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