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Linear Resonant Actuators

A project log for Digital White Cane

The Digital White Cane can prevent frequent head injuries and provide intuitive navigation assistance for the blind and visually impaired.

George AlbercookGeorge Albercook 10/21/2017 at 01:061 Comment

There are two main haptic feedback technologies. Eccentric Rotating Mass (ERM) and Resonant Linear Actuators (RLA). Fancy terms for pager motors and speaker coils. Well it is not exactly that simple. The RLA have a frequency that the prefer to work at while speaker coils are designed to work at a wide range of frequencies. 

We started with ERM actuators. They wabble around in a little circle as the motor tries to spin the off center weight. They are cheap but they are hard to control precisely. At low power the motors don't want to start so it is hard to get a large range of intensities out or them. They also take time to change power levels and tend to get warm at high power.

So we wanted to try LRA which oscillate up and down like they are bouncing. They start, stop and change amplitude quicker than the ERM devices do and they don't heat up. So we bought some.

Discussions

Slinger wrote 01/05/2018 at 04:15 point

You're right, if you need precise control of the vibration motor, you need to use the LRA - linear resonant actuator, some latest iphone are using the LRA instead of ERM. LRA offers a super quick response and controlled by the IC supplied by the TI - https://goo.gl/ZSvXK8

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