Point Mass Bodies

The point mass body is a reduced version of the six DOF rigid body. It only has three translational DOFs, therefore the point mass body has mass but no inertia properties. The position of a point mass is defined by a center of mass point. By default, the orientation of the point mass is set to be the same as the Global Coordinate System (which never changes during simulation). The purpose of a point mass entity is to add additional representative weight to another body, for example the mass of a driver on a seat.

  1. If the Bodies panel is not currently displayed, select the desired body by clicking on it in the Model Browser or in the modeling window.
    The Bodies panel is automatically displayed.
  2. Enter a mass for the body in the Properties tab.
    Note: If the selected body is a pair entity, first distinguish between the Left and Right tabs in the panel, and then edit the properties.
    Tip: Check the Symmetric properties option to make the body properties symmetric. Once this option is activated, MotionView will ask you which side of the values of the pair entity (left or right) is to be used. Selecting any one side will make values of that side as “leader” and the values of the other side will gray out and follow the values on the leader side.
  3. Click the CM Coordinates tab.
  4. Click the Use center of mass coordinate system check box to select a point as the origin of center of mass for the body.
    Note: If a center of mass coordinate system is not specified, MotionView assumes that it coincides with the global frame of the model.
  5. Click Point and select the appropriate center of mass point.
  6. Use the orientation options to orient the coordinate system.
  7. Define initial conditions.
    1. Click the Initial Conditions tab on the panel.
    2. Select the desired check boxes and enter values for linear velocity.
      Note: Linear velocities are specified with respect to the global reference frame.