Adams Basic Package > Adams View > View Function Builder > Run-Time Functions > Functions: A - M > Difference between translational velocity vectors (VXYZ)

Difference between translational velocity vectors (VXYZ)

The VXYZ measure returns the difference between the velocity vector of marker i and the velocity 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

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

Arguments

 
Applied To Marker (i)
The marker whose origin is being measured.
Applied From Marker (j)
The marker with respect to which the velocity 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 you need to specify k or l.
Along Marker (k)
The marker in whose coordinate system the velocity 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 you need to specify l.
Reference Frame (l)
The reference frame in which the first-time derivative of the displacement vector is taken. Set l = 0 or omit the argument if you want the time derivatives to be taken in the global reference frame.

Extended Definition

Mathematically, VXYZ is calculated as follows:
where:
■ is the displacement of marker i in ground.
■ is the displacement of marker j in ground.
■VX is the Velocity Along X (VX) measure.
■VY is the Velocity Along Y (VY) measure.
■VZ is the Velocity Along Z (VZ) measure.
■ denotes time differentiation in the reference frame of the l marker.

Examples

This variable statement:
VARIABLE/1, FUNCTION = VXYZ(21,11) * UV(DXYZ(21,11))
computes the projection of the velocity vector of marker 21 from marker 11 on a unit vector along the line of sight to marker 21 from marker 11. This quantity is also known as the radial velocity and can be written more compactly as:
VARIABLE/1, FUNCTION = VR(21,11)