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Question about connecting many sensors to a phone simultaneously vs. something like the MetaHub?

gammonmgammonm
in Hardware

I have developed an that involves controlling a virtual avatar's lower body using anywhere from 3-7 MMC sensors. I find when we are only using 3 sensors my app works quite well but when we bump it up to 7 the connection is a lot more spotty and unless I increase the max connection interval for the sensors (causing a slower response time which is undesirable for our real-time application) the background android service tends to crash randomly. This hasn't been such a problem so far, but we are moving toward the stage of testing this app with some medical patients and other people outside our lab, and it is now important to make sure that things are stable.

i'm wondering if this is to be expected when connecting so many sensors to a phone (Samsung galaxy S8) or if it is more likely just poor coding on my part (I'm not a programmer by trade so it's likely that this is the case). If the former, would using something like the MetaHub as an intermediate device improve the performance?

Thanks,
MG

Comments

  • LauraLaura
    edited September 2019

    This has unfortunately absolutely nothing to do with us.

    It's the Samsung galaxy S8 and other smartphones that have a connection bottleneck.

    Keep in mind iOS restricts the # of connected devices, as does Android.

    Also, the one 2.4Ghz antenna is shared between all devices AND WIFI! that's a lot on one tiny antenna!!! You're going to get lag and restrictions!

    The thing is, smartphones were NEVER meant to be able to connect to multiple slave devices. You can google more about this if you are bored.

    That's why you should use the Metahub, which is essentially just a mini linux computer (the raspberryPi) which has the flexibility and programmability (and scalability) to do what you want with it (like connect many slave devices).

  • gammonmgammonm
    edited September 2019

    Thanks for your help. This is maybe a silly question but is the MetaHub meant to be an intermediate device? In other words would I be able to connect the Android phone to the metahub and then have a smooth connection to many sensors' Quaternion values from the phone? The entire application is based around Android so unless this is possible we will have to find another solution.

    In the mean time I'll do some more research of my own but as of right now it's unclear to me whether the Metahub is meant to be a standalone device or a middleman to something like a smartphone.

  • LauraLaura

    No, the metahub is meant to replace the smartphone.

  • jonathanslicktechsjonathanslicktechs

    Hi there, just jumping to ask a question related to what was discussed above.

    Is the connection to multiple sensors still impossible or is there a solution since this discussion happened? I'd like to connect MMR to map the whole body movement (ideally on MMR/moving joint), ideally, 12 MMR connected simultaneously.

    Any thoughts?

    Thank you.

  • LauraLaura

    You need to use a Linux based computer with multiple dongles to support this.

  • Mo130Mo130

    Hi
    If I want to use more than 30 devices to get the data simultaneously, using only 2 dongles from available USB ports (4) in Metahub is not enough. What should be a solution in Metahub to connect more devices (>30) at the same time?

  • LauraLaura
    edited April 2021

    Use a USB port and more dongles (if you use only 2 dongles it's a lot of traffic for bluetooth).

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