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Positioning, Tree File

  • The H-point is located at the node 10500.
  • In the delivered file the H-Point coordinates are:


x coordinate
y coordinate z coordinate
H-Point -128.67900


  • The USSID model is delivered with a tree-file for OASYS-Primer preprocessor (may also work for ALTAIR-Hypermesh, not verified by DYNAmore). This allows the user to position the dummy and adjust the parts according to their degrees of freedom.

    In the H-Point of the dummy model, two coordinate systems are modelled. These coordinate systems are connected to each other by a spherical joint. One coordinate system is connected to global directions, that means only translations are possible, rotations are disabled. The other one is connected to the dummy, thus making it possible to measure the pelvis angle of the USSID during the positioning simulation quickly and easily . These coordinate systems are also used to determine the initial pelvis angle with OASYS-Primer.



Fig. 7: Coordinate System of Pelvis

  • The pelvis angle of the delivered model is:  10.6 degree. It is measured as depicted in the left picture below. The right picture shows the model in the upright position, that means with a pelvis angle of 0.0 degree.


Fig. 8: Delivery Position

  • No PART_INERTIA Cards are used. Hence, a common pre-processor may be used to handle the model.

  • The lower legs and feet have a rotational degree of freedom along the y-axis. The position of  other parts of the body are determined by the H-point and the pelvis angle.The upper legs of the USSID v5.0 model also have rotational degrees of freedom, but it is not recommended to move them because initial penetrations would occur. This reaction is based on the hardware model. That is the reason why the degrees of freedom for the upper legs are disabled in the OASYS-Primer tree-file. It is better to position the upper legs by a pre-simulation. A special positioning-file <positioning\_ussid\_v5.0\_mm\_ms\_kg.key> is delivered to perform this pre-simulation.

  • The positioning file of the USSID is very easy to use. At the top of this file you will find a set of parameters to be defined. These parameters are shown in the following table:

Parameter Description
term  termination time
 tmove time to move parts
 trans_x translation of whole dummy model in x direction
 trans_z translation of whole dummy model in z direction
 lfemry left femur rotation about y
 rfemry right femur rotation about y
 lfemrz left femur rotation about z
right femur rotation about z

As a second step, you have to fill in your include-files necessary for positioning the dummy model. Usually only the seat     model and the dummy model are used for the positioning procedure.

Please define a  *CONTACT_AUTOMATIC_SURFACE_TO_SURFACE for contact between the dummy and seat(environment). The USSID properties for this contact are defined in the part set 1500.

  • The axis of the revolute joints can be defined by:

Joint 1st Node
2nd Node
Left knee
10800  10802
Left ankle
 10808  10810
Right knee
 10816  10818
Right ankle
 10824  10826

  • The centre of the spherical joints can be defined by:

Joint Node
Left femur
Right femur