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I have noticed from a drone (of a friend of mine) it has a feature that lets its motors beep so when it gets lost it can be easily found. I have some searching and this seems to be done by alternating turning forward and backward quickly enough for the motors not be able to spin.

I would hopefully like to exploit this characteristic as maybe a feedback to the user for example a button is pressed and the motors would beep, this would mean that I do not need a piezo speaker.

But will this cause some damage to the motor or motor driver? My intuition is telling me it does, but on some commercial products (drones) or high performance robots (the one used in competitions) I often hear these beeps.

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    \$\begingroup\$ Drone motors are probably BLDC motors. Brushed motors are less suitable for beeping. \$\endgroup\$ – Brian Drummond Jan 25 at 10:09
  • \$\begingroup\$ Just for fun: Search on youtube for "Flopotron". \$\endgroup\$ – Jahaziel Jan 31 at 20:13
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Summary: Safe enough unless you try really really hard to design it to be destructive.

It MAY be possible to damage the motor this way if you tried hard enough, but that applies to any use of the motor, and it will be very easy to implement such a system without harming the motor. Controllers usually have inbuilt hardware or software mediated protection systems which prevent one applying excessive levels of stupidity. Even without this it would be hard to destroy a system at sensible power levels.

Issues may include

  • Causing excessive thermal dissipation by applying high energy levels without the cooling usually afforded by the propellor downdraft

  • Operating the motor at zero revs is its potential highest torque point - if you were going to break something this will be a likely region to do it. But, any system not designed to easily withstand peak torque, even repeatedly applied, is not a well designed one.

  • Operating a motor in reverse applies reverse torque to the propellor to shaft coupling. Some systems use appropriate sense left or right hand threads to lock the propellors in position. Even almost zero revs reverse torque will tend to unlock the propellor - BUT it will be locked again by the next half cycle of 'sound' drive. and properly locked again when normal motion is applied.


Bonus:

For "extra points" you may be able to make it talk.
"Help me. Help me. I'm over here ...".
(I've heard of road surfaces designed to make a car's suspension "talk" - decipherable "speech".)

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  • \$\begingroup\$ Thanks for that answer good sir, I dont plan on making it talk yet. Im more concerned of the motor itself rather than the driver, the driver is fairly a new part and packed with features. It can handle way way more amps than what the motor needs. Although the motor is rated for high performance ( stronger carbon brush) it still does worry me so i will keep the beeping to a minimum \$\endgroup\$ – Jake quin Jan 25 at 14:47
  • \$\begingroup\$ You'd definitely be safer beeping a brushless motor over a brushed motor. I'm not sure whether you'd risk damage to the brushes doing this. I can verify with certainty that there is essentially zero risk with a brushless motor, if properly implemented as Russell stated \$\endgroup\$ – Ocanath Jan 31 at 19:05

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