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Coordinate transformation - NED and ECEF frames

  1. Oct 6, 2015 #1
    Hi,

    I have a reference device that outputs euler angles, which are angles that relate the sensor body frame to the north east down frame. These angles are called pitch roll and yaw. The sensor is an accelerometer. I know how to get the rotation matrix that will put accelerations from the accelerometer sensor body frame to the north east down frame. Call this rotation matrix R(Body to North East Down).

    How do I get the rotation matrix that will rotate from Body frame to Earth Centered Earth Fixed frame? I need to do this as all of my other calculations use the Earth Centered Earth Fixed frame. I can see that:

    R(Body to Earth Centred Earth Fixed) = R(Body to North East Down) * R(North East Down frame to Earth Centered Earth Fixed).

    How do I get R(North East Down frame to Earth Centered Earth Fixed)?

    To get acceleration in the earth centered earth fixed frame, would I use:
    Acceleration(Earth Centred Earth Fixed) = R(Body to Earth Centred Earth Fixed)*Acceleration(Body frame) ?

    I have access to the position in latitude and longitude (radians). Also note that acceleration is a vector not a coordinate.

    Thanks.
     
  2. jcsd
  3. Oct 11, 2015 #2
    Thanks for the post! This is an automated courtesy bump. Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post?
     
  4. Oct 11, 2015 #3

    FactChecker

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    Latitude and longitude give you the rotation angles to convert from NED to ECEF. I am working from vague memory, but I think that the latitude gives the rotation angle needed even when you are using the accurate WGS84 Earth model. If you have magnetic north, don't forget to rotate to true north.
     
  5. Oct 13, 2015 #4
    R(North East Down frame to Earth Centered Earth Fixed) =

    [ sinLatitude*cosLongitude; -sinLongitude; -cosLatitude*cosLongitude]
    [-sinLatitude*sinLongitude; cosLongitude; -cosLatitude*sinLongitude]
    [cosLatitude; 0; -sinLatitude; ]

    I am unsure if this is correct for my application because this may only be relevant for coordinates not vectors. Please comment.
     
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