I'm using a cheap dc motor (this one). The motor shaft is attached to a spool. When the motor is powered off, the spool will unwind. I want to have control over when it unwinds. Is there a way of braking the motor shaft and to stop it from rotating by just using the motor driver? If not can you suggest other ways to stop a motor shaft from rotating?
You can use a solenoid to mechanically hold the shaft.
Withdraw the solenoid, move motor, stop motor, release the solenoid.
Using an encoder showing the axle rotation is one option.
Some kind of electromagnetic brakes is another.
I've used solenoids before and they heat up really easily, I need to stop the shaft from rotating several hundred times. Oh and they're quite noisy, I need a quieter option
You can brake such a motor by shorting it’s connections , but that won’t hold it stationary .
If your motor drives via worm type gearbox , that would mean it would hold stationary.
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+1 for worm gear drive. It can't be driven backwards, so no power is required.
Many motor drivers have a brake mode where the motor is shorted and acts as a (shorted) generator. This will slow down and finally stop the motor.
You also can reverse the motor direction, but then you have to know when the motor stalls and should enter brake mode.
Once stopped tho it wont take much torque to move it . You can’t really leave power on a stalled motor , the current drain would be high And the motor get hot
Torque of a shortened and open motor is significantly different.
Why would you apply power instead of shorting a stalled motor?
Whilst the motor is turning it is acting as a generator and the short circuit works against this and slows the motor . Once it’s stopped the braking force has gone .
Hence , if you then wanted to keep the motor stationary you would then need to power it against any external force .
Power makes the motor turn, not stationary. The short circuit works against external force. It's not an absolute fixing brake, though.
Motor braking will take too long. Better to make a brake for the spool!
Use a stepper or closed loop servo.
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