Speed limits

Submitted by jside on Sun, 05/11/2014 - 19:06

Forums:

Hi,

I'm using the provided Python libs for the Picoborgrev to drive a stepper motor. In the example scripts the stepping loop is set to sleep for 0.002 seconds. Consistent speed is important to my application so I am subtracting the time it takes to send the motor commands from the desired delay time. It seems 0.002 seconds itself is typical for execution of SetMotor1 and SetMotor2.

Where does the speed limitation lie? I'd like to drive my stepper motor faster if possible.

Thanks,
Cary

piborg's picture

piborg

Mon, 05/12/2014 - 09:08

The reason for the delay is the stepper motor itself.

Stepper motors take an amount of time to actually perform a single step, in order to operate properly they need to have completed the previous step before making the next one.

If you know the step time you can reduce the delay to the required amount, otherwise you can lower it by experimentation.

If the delay between steps is too small then you may experience any of the following problems:

  • The motor does not move
  • The motor rotates very slowly
  • Loud or nasty noises from the motor
  • The motor misses steps occasionally

If the motor responds fast enough then the call to perform the next step may have enough delay already and the sleep may not be required.

jside

Mon, 05/12/2014 - 19:08

Great info, thank you.

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