I want to use vibro-tactile stimulation for changing brain activities, but there are issues in controlling vibration motor frequency using PWM.
For example, researchers stated that they controlled stimulation frequency as 21~25Hz with 1Hz steps (resonant-like frequency) using PWM with Aruduino Due.
I don't really understand what they have done.
To my knowledge, vibration motor has their own RPM, and it can be converted to Hz by RPM/60.
Can I control vibration motor frequency specifically by merely control PWM value?
Thank you Best regards, Kyungho Won