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# euler or quaternion transform

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 afonda (Automotive) 11 Oct 01 8:49
 Does Matlab support Euler or quaternion transforms?I have searched this website for those words and found nothing. If it can be found in Matlab itself (I do have access) I don't know where to find it.I have spread sheets with 3-axis accelerometer data and 3-axis rate gyro data. I believe I need to stepwise integrate the rates to know the rotated (vehicle) axes, then transform both rate and acceleration data to earth axes, then repeat for the next time step. Anyone familiar with this?ASAP, please. Time has been a-wasting with zip for results.afonda@crashex.com
 afonda (Automotive) 23 Oct 01 8:55
 While the Euler geometric equations have the proper outputs, they do not have the proper inputs; rate gyros read rates about body axes, which are not rates of change of the Euler angles. This ought to be a standard aeronautic/aerospace problem. How does Ground Control interpret the signals from the on-board instrumentation???? I should not have to re-invent the wheeel.AGF
 enkodham (Aerospace) 30 Oct 01 2:00
 Why can't you have Matlab read in the file with the gyro and accelerometer data, make it into a matrix, and process the data through a quaternion transformation to whatever reference frame the quaternions relate the information to?There are several text books out there that have the quaternion transformation matrix...you have to know which element (first or last) is the actual rotation element. Some people have it as the first and others as the last...
 afonda (Automotive) 30 Oct 01 7:50
 Please be specific. You have so far confirmed that I already understand the problem. What I need is the procedure, as distinct from the name of the type of procedure. I need the actual matrix which does the transform.
 enkodham (Aerospace) 3 Dec 01 23:11
 Spacecraft Dynamics and Controls...a book by Bong Wie. You'll find your quaternion-based transformation matrix there...
 afonda (Automotive) 18 Feb 02 20:29
 Enkodham: I'll check the text, but in the meantime I hired a Vilanova Engineering Dynamics grad student to do it, and he has written a nice program in Matlab. His final assignment is to check the state of the art, lest when report the transformed data we wrongly claim novelty; so the citation will help. I never thought it should be novel to start with; but except for Bong Wie it gives that appearance.     AGF
 knoxj (Aerospace) 25 Mar 02 10:08
 This is late. I agree with the above. I have validated MATLAB  the converts from DCM to quat to DCM. Will e-mail it you are interested. Texts by SIDI and Jack Kuineper? are good. They are on Amazon. - jk

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