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How strong can LRA- motors (generally) vibrate?

Marina Maier
Prodigy 15 points

Hi Everyone, 

I am a Master student (User Experience Management) from Austria .  I am doing my thesis on vibration stimuli as haptic feedback on mobile devices.

I do have a great problem: I can not find any information on how strong a Linear resonant actuator can (generally) vibrate.

I need this information to validate my current test design. I'm actually using a Joy Con (Nintendo switch controller) to see if my test subjects (firefighters, rescuers, armed forces, etc.) can feel the power of such a motor (thresholds), despite protective clothing, at different parts of the body, etc. I use this device because it can be easily prepared for laboratory design (vibration patterns can be triggered remotely, handy and commercially available device).  The question is: Is this motor comparable with a standard motor in a Samsung or Apple phone (in terms of vibration strength)?

I only know that the motor in the Joy-Con is a LRA and that this model is rectangular. The exact engine type etc. could not be determined. Comparative values from the smartphone manufacturers could not be obtained either.

Can you guys help me?

kind regards

Marina

  • 0
    TI__Guru* 84915 points

    Hi, Marina,

    Welcome to E2E and thank you for your interest in the actuators!

    In order to understand some of the LRA strengths and limitations, I think that the better would be to do a comparison between some of the actuators that our TI actuators drivers support.

    Our actuators drivers product folder may support different kind of actuators families such the LRA, ERM, Piezo, Solenoid and Piezo Bender. The most popular devices are the LRA, ERM and Piezo actuators.

    The table below show a little comparative between these three devices:

    ERM LRA PIEZO
    Voltage 1 - 10 VDC 2.5 - 10 VAC 50 - 200 Vpp
    Acceleration (G) ~ 1 ~ 1 - 2 ~ 1 - 3
    Power Consumption Good Best Better
    Audible Noise Very Noisy Moderately Noisy Silent
    Response Time 40 - 80ms 20 - 30ms < 1ms

    Piezo devices use to have a better performance. However, it is a trade off between cost and performance. By the other hand, the ERM actuators have the lowest cost and performance. The LRA would be at medium cost and performance.

    The LRA actuators offer a good response time (compared with the ERM). It is fast enough to support multiple letters while the user is texting. It may reach multiple letters per second for button-press confirmation.

    However, the LRA devices have a fixed frequency at the resonance frequency since it may only vary around  +/- 5Hz.

    When the LRA is used at the resonance frequency, the actuator may reach its highest strength. This value may vary depending of the manufacturer. So, in order to determine the acceleration of the actuator, you may use some tools so it can be determined in an easier way. I would suggest to take a look at the tool below, it may be useful for you.

    http://www.ti.com/lit/ug/slou402/slou402.pdf

    For complementary information about the actuators and our haptics devices, you may take a look at the links below:

    https://e2e.ti.com/blogs_/b/analogwire/archive/2017/10/26/the-next-generation-of-linear-resonance-actuators

    https://e2e.ti.com/blogs_/b/analogwire/archive/2016/08/09/eight-things-to-consider-when-choosing-haptic-feedback-part-1

    https://e2e.ti.com/blogs_/b/analogwire/archive/2016/08/18/eight-things-to-consider-when-choosing-haptic-feedback-part-2

    Please let me know if you have additional questions or comments on this.

    Best regards,
    Luis Fernando Rodríguez S.