ACCM
The ACCM function calculates the magnitude of the second time derivative of the displacement vector of marker i from marker j. The time derivatives are taken in the reference frame of marker l. Markers j and l default to the global coordinate system and the global reference frame if they are not specified.
Format
ACCM(i[,j][,l])
Arguments
i | The marker whose acceleration is being measured. |
j | The marker with respect to which the acceleration is being measured. Set j = 0, while still specifying l, if you want j to default to the global coordinate system. |
l | The reference frame in which the second time derivative of the displacement vector is taken. Set l = 0 or omit the argument if you want the time derivatives to be calculated in the ground coordinate system (GCS). |
Extended Definition
Mathematically, ACCM is calculated as follows:
where 
is the displacement of marker i in ground and 
is the displacement of marker j in ground.
is the displacement of marker i in ground and is the displacement of marker j in ground.Note that for any vector quantity 
:
:
Examples
REQUEST/10, F2=ACCM(21,11)
This statement defines the second component of a user-defined request as the magnitude of translational acceleration of Marker 21 with respect to Marker 11. Since the l marker is not specified, the derivatives are taken in the inertial reference frame.
REQUEST/10, F2=ACCM(21,11,32)
This statement defines the second component of a user-defined request as the magnitude of the translational acceleration of Marker 21 with respect to Marker 11. Vector time derivatives taken in reference to Marker 32.
See other Acceleration measures available.