WDTM
The WDTM function returns the magnitude (in radians per units of time squared) of the difference between the angular acceleration vector of marker i in the reference frame of marker l and the angular acceleration of marker j in the reference frame of marker l.
Note: | The values returned by the functions have the same units defined in the UNITS statement except for angular values. All angular values are returned in radians, all angular velocities are returned in radians per units of time (as defined in the UNITS statement), all angular accelerations are returned in radians per units of time squared. Functions RTOD and DTOR may be helpful to create angular expressions involving degrees and radians. For example, the below statements create a constraint to keep the angular velocity WX(8, 9) equal to 2.5 degrees per second. UNITS/SYSTEM = MKS ! Using seconds GCON/1, FUNCTION = WX(8, 9) – 2.5*DTOR ! Convert degrees to radians |
Format
WDTM(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 i, if you want j default to the global coordinate system. |
l | The reference frame in which the first time derivative of the angular velocity vector is taken. Set l = 0 if you want the time derivatives to be taken in the ground reference frame. |
Extended Definition
Mathematically, WDTM is calculated as follows:
where:
■
is the angular velocity vector of marker i in ground.
is the angular velocity vector of marker i in ground.■
is the angular velocity vector of marker j in ground.
is the angular velocity vector of marker j in ground.Examples
MARKER/1236, QP=4,6,7 EU=90D,90D,90D, PART=23
MARKER/2169, PART=16
REQUEST/16
,F1=WDTM(1236,2169)/
,F2=WDTX(1236,2169,2169,2169)/
,F3=WDTY(1236,2169,2169,2169)/
,F4=WDTZ(1236,2169,2169,2169)
MARKER/2169, PART=16
REQUEST/16
,F1=WDTM(1236,2169)/
,F2=WDTX(1236,2169,2169,2169)/
,F3=WDTY(1236,2169,2169,2169)/
,F4=WDTZ(1236,2169,2169,2169)
In its first column REQUEST/16 contains the magnitude of the angular acceleration vector of Marker 1236 with respect to Marker 2169, as seen in the global coordinate system and measured in the ground reference frame.
See other Acceleration measures available.