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I have started to work on a little project of mines, which consists in implementing the stabilization a single axis gimbal using Arduino.

The gimbal is driven by a sensorless three phase brushless DC (BLDC) motor, while on it's shaft there is a generic payload provided with an IMU board (3 axes gyros + 3 axes accelometers), which can give feedback to the Arduino about the angular rates and accelerations.

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I have googled a bit about this topic and there are so many solutions out there, the only thing I really do not understand is about the control of the BLDC motor.

  1. Can I use a sensorless control of the motor, by sensing the back EMF even if the motor is spinning very low?
  2. How can I energize properly the phases of the BLDC motor if it is sensorless?
  3. Can I use the IMU for finding out how to spin the BLDC motor properly without counter rotations?

Could you give me any help, please?

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2 Answers 2

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consider coupling the motor with an encoder that has enough resolution to tell you precisely when to ramp up current to a particular phase. this will give you precise feedback to develop a control loop that should give maximum torque for a given voltage.

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    $\begingroup$ Actually, I don't want to use any encoder as it introduces extra costs to the whole system. $\endgroup$
    – starScream
    Commented Oct 18, 2016 at 6:05
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    $\begingroup$ i found this paper: ncbi.nlm.nih.gov/pmc/articles/PMC3231115 $\endgroup$
    – user15033
    Commented Oct 18, 2016 at 11:34
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Are you opposed to adding components to the power circuit? If you add in a portion that measures current being drawn by the motor, you can get some decent feedback about what the motor is doing and how much of a mechanical load is being applied to it.

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  • $\begingroup$ It isn't that I'm opposed in adding components, the point is that I would like to achieve my goal by using what I currently have. Maybe in the future I would add current sensors. $\endgroup$
    – starScream
    Commented Nov 21, 2016 at 18:08
  • $\begingroup$ That's reasonable. I'm just a big fan of the current sensing method to get a quick 'status' of a motor. $\endgroup$
    – MechanicalMan
    Commented Nov 21, 2016 at 18:11

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