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WDTXYZ

The WDTXYZ measure returns the difference between the angular acceleration vector of marker i and the angular acceleration vector of marker j resolved in the coordinate system of marker k. All vector time derivatives are taken in the reference frame of marker l.

Format

WDTXYZ(i[,j][,k][,l])

Arguments

 

i	The marker whose acceleration is being measured.
j	The marker with respect to which the angular acceleration is being measured. If j is not specified, it defaults to the global origin. Specify j = 0 if you want to use this default, and then specify k or l.
k	The marker in whose coordinate system the angular acceleration vector is being expressed. If not specified, k defaults to the global coordinate system. Specify k = 0 if you want to use this default, and then specify l.
l	The reference frame in which the first time derivative of the angular velocity vector is taken. Set l = 0 or omit the argument if you want the time derivative to be taken in the global reference frame.

Extended Definition

Mathematically, WDTXYZ is calculated as:

where:  

•	is the angular velocity vector of marker i in ground.

•	is the angular velocity vector of marker j in ground.

•	denotes time differentiation in the reference frame of the l marker.

•	WDTX is the WDTX measure.

•	WDTY is the WDTY measure.

•	WDTZ is the WDTZ measure.

•	is the unit vector along the x-axis of marker k.

•	is the unit vector along the y-axis of marker k.

•	is the unit vector along the z-axis of marker k.

Examples

A vector expression for angular acceleration might be used directly in the definition of a vector torque element:

VTORQUE/3, I=310, JFLOAT=9911, RM=310,
, TXYZ = -6.*WDTXYZ(310,9900,310)