Shop OBEX P1 Docs P2 Docs Learn Events
Any one use an accelerometer ? — Parallax Forums

Any one use an accelerometer ?

grasshoppergrasshopper Posts: 438
edited 2008-12-12 15:58 in General Discussion
I have some questions:

Do they send out the negative G's as well as the positive?

If so this could technically give a persons velocity a.k.a. MPH. Please comment on your accelerometer pors and cons.

Comments

  • FranklinFranklin Posts: 4,747
    edited 2008-12-12 04:42
    Why not Google search for answers? If you Google sitetongue.gifarallax.com you will find quite a few references that will explain them . Or you could use wiki

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    - Stephen
  • LeonLeon Posts: 7,620
    edited 2008-12-12 06:49
    Read some accelerometer data sheets (ST, ADI and Freescale).

    Leon

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Amateur radio callsign: G1HSM
    Suzuki SV1000S motorcycle
  • sylvie369sylvie369 Posts: 1,622
    edited 2008-12-12 14:57
    The forum is full of pros and cons of accelerometers, as well as specifics about the challenges of getting velocity and worse, position data from acceleration.

    Generic forum use advice: read other people's questions, and the answers. There's lots of good stuff already out there.

    I'm guilty of failing to do this myself, when about a month ago I asked if servos and their controllers need to share a common ground - becoming apparently the 10,000th person to ask that same question.
  • AImanAIman Posts: 531
    edited 2008-12-12 15:51
    Check out this thread

    http://forums.parallax.com/forums/default.aspx?f=15&m=308626
  • Carl HayesCarl Hayes Posts: 841
    edited 2008-12-12 15:58
    sylvie369 said...

    I'm guilty of failing to do this myself, when about a month ago I asked if servos and their controllers need to share a common ground - becoming apparently the 10,000th person to ask that same question.
    That seems a rather innocent kind of guilt, Sylvie.· If there were anything wrong with asking questions that have been answered before, no one except an Einstein could ask any questions at all.· When I ask a question here (or anywhere) it's because I hope it has been asked and answered before, and that someone present may remember the answer and be sufficiently articulate to give it.

    One can, of course, Google for an answer.· Then one gets a haystack that may have·in it the #3 Singer sewing machine needle one needs, or may not have it, but that·is certain to be full of pine needles, cactus needles, knitting needles, maps of the city of Needles, California, and a complaint that little Joe Glotz needles his big sister a little too much about her acne.

    Responding to the original question, accelerometers reasonably available to hobbyists do indeed measure acceleration as positive and negative.· This, however,·does not enable one to determine velocity with useful accuracy, nor position with any accuracy at all, because (1) the accelerometers don't have sufficient resolution or accuracy, and (2) the microcontrollers can't calculate with sufficient precision.

    It is·possible to determine changes in·velocity and position from accelerometer data -- that's what INS systems do -- but the accuracy and precision required are, by several orders of magnitude, ·beyond amateur capabilities and amateur budgets.· And even the best inertial navigation systems require frequent updates from other navigation systems in order to correct accumulated error.· They're great for short-term use when the GPS drops out, though, if you've got an extra·couple hundred grand to spend.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    · -- Carl, nn5i@arrl.net
Sign In or Register to comment.