The FZ function returns the z-component of the net translational force acting at marker i, as computed in the coordinate system of marker k. All force and constraint elements acting between markers i and j are included in the calculation of the force, unless a force is an action-only type force. To return the z-component of the action-only forces acting at marker i, you should omit specification of marker j or specify it to be zero. Note that you can not specify marker k and omit marker j. In this case, you should specify marker j to be zero.
FZ(i[,j][,k])
| i | An integer that specifies the identifier of the marker at which the magnitude of the net force is to be calculated. |
| j | A second integer that specifies a marker identifier. All forces acting between the [i,j] pair are to be included in the calculation. Set j = 0 or do not specify it if you are interested in action-only forces. |
| k | An integer that specifies the identifier of a marker (coordinate system) in which the z-component of the force is to be returned. k defaults to the global coordinate system when it is not specified. |
STEP(FZ(34), -1.5, -200, 1.5, 200)
This equation uses the value of the force of the step function. The independent variable for the STEP function is FZ(34), the net force acting along the global z-axis at Marker 34. Because no j marker is specified, only action-only forces acting at Marker 34 are included in the calculation of FZ().