AB-031 : Vibration Motor Calculators – ERMs and LRAs

Here you will find various calculators for vibration motors to help you specify your motors, or understand various characteristics. This Application Bulletin is updated as more calculators are developed, so you can always find all the tools in one place.

Quick Vibe Estimator

Originally posted in our Tech Blog article “Why is Amplitude in G?”, this calculator pulls together several different equations to quickly estimate the outputs of a simple vibration system. By playing around with different inputs, you will notice things like how the vibration frequency directly relates to the motor speed or the displacement decreases with motor speed.

If you are interested in learning more about the theory behind this calculator, the following Application Bulletins should help:

Please note there are a few limitations. Both the resulting acceleration and displacement are dependant upon the weight of the target mass, this makes sense because you can intuitively tell a heavier object will not move as much as a light object when the same motor is attached. So if you don’t enter a target mass, you will end up with an infinite displacement!

Vibration Frequency Calculator

This calculator can be used to either calculate the vibration frequency of an ERM from the motor speed, or the motor speed from the desired vibration frequency. Simply enter your new speed in RPM or frequency in Hz, if you have a specific motor in mind then both these values can be found on the datasheet.

As both the speed and frequency are dependant on the voltage applied (higher voltage gives the motor more power to turn quicker), you may find it useful to consider a range of results.