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Subtracting centrifugal acceleration from acceleration caused by movement

  1. Nov 8, 2011 #1
    I've been playing around with dead reckoning stuff on an rc plane by attaching a gps, 3 axis gyroscope, and 3 axis accelerometer to the plane.

    When the plane isn't turning, my algorithm works pretty well however when I enter a turn, the readings get way off. Specifically, the plane appears to be moving at a faster velocity than it actually is thus all turns are overshot.

    I believe I see this due to centrifugal acceleration and would like to cancel it out, but I'm getting quite lost, especially with 3d vectors. How might I go about subtracting this observed acceleration from acceleration caused by movement?

    Thank you
     
  2. jcsd
  3. Nov 8, 2011 #2
    Let me add what I have identified so far.. for at least identifying what I believe to be the acceleration component I need to subtract:

    F = ma[itex]_{c}[/itex] = (mv[itex]^{2}[/itex])/ r = mrw[itex]^{2}[/itex]

    The definitions are standard as of this wiki page:
    http://en.wikipedia.org/wiki/Centripetal_force

    I know:
    (gps) speed = v
    (gyroscope) angular velocity = w

    I can calculate r via:
    (mv[itex]^{2}[/itex])/ r = mrw[itex]^{2}[/itex]
    v[itex]^{2}[/itex]/ r = rw[itex]^{2}[/itex]
    v[itex]^{2}[/itex] = r[itex]^{2}[/itex]w[itex]^{2}[/itex]
    r[itex]^{2}[/itex] = v[itex]^{2}[/itex] / w[itex]^{2}[/itex]
    r = [itex]\sqrt{v^{2} / w^{2}}[/itex]


    With r and w known, I can now calculate [itex]a_{c}[/itex] as follows:
    m[itex]a_{c}[/itex] = m[itex]rw^{2}[/itex]
    [itex]a_{c}[/itex] = [itex]rw^{2}[/itex]

    Am I anywhere close to being on the right track? :rofl:
     
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