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MEMSIC 2125 sensor to use for an airbag — Parallax Forums

MEMSIC 2125 sensor to use for an airbag

TomTomTomTom Posts: 6
edited 2009-12-01 18:39 in Accessories
Hello !
I am looking for some code to get only accelaration from the MEMSIC 2125 sensor..
That means, no mather if my object is even or tilted, just need to know the acceleration if it´s pushed to start an action just like an airbag in a car might work.

Thank you all for your help.
Tom

Comments

  • SRLMSRLM Posts: 5,045
    edited 2009-11-30 17:07
    Just to clarify: an accelerometer can only measure acceleration. Now, the measured acceleration can be categorized into two types: dynamic and static. If you want to measure just one then you will need some more input into your system. Usually this is in the form of adding some gyros and creating an IMU. Note that most IMUs use this setup to calculate tilt (attitude), but it could be used to calculate dynamic acceleration.
  • TomTomTomTom Posts: 6
    edited 2009-12-01 12:31
    Hello,

    thank you very much for your reply.

    As far as i got it, i need dynamic acceleration.
    I wanted to know, if this is possible with the MEMSIC 2125 sensor and my BS2, just as i guess an airbag works,to measure dynamic acceleration apart from tilt.


    What are your experiences ?
  • FranklinFranklin Posts: 4,747
    edited 2009-12-01 16:32
    The airbag sensor measures a high delta g change indicating a crash (perhaps 10 to 20 G) so tilt does not affect it as it would if you were measuring small G forces. I don't know what the range of the 2125 is so you would have to decide if it would work.

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  • TomTomTomTom Posts: 6
    edited 2009-12-01 17:10
    Hello !

    You are perfectly right, but in fact: i am not going to install this in my car, so the Parallax MEMSIC 2125 looks like it will do this job.
    I was just wandering, if anybody knows some code in combination with a BS2 to handle this.
    Till now i could only find some examples, dealing with tilt.

    Thanks for your help.
    Thomas
  • kwinnkwinn Posts: 8,697
    edited 2009-12-01 18:36
    If the tilt of your sensor is fixed the acceleration due to the tilt is constant and can simply be subtracted out.
    If the tilt varies then it has to be measured and the acceleration due to the tilt calculated or looked up and subtracted out.
  • kwinnkwinn Posts: 8,697
    edited 2009-12-01 18:39
    PS - If the tilt varies in relation to the direction of acceleration that also has to be taken into account.
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