Relative rotation definition

@EDGE_NAME {EdgeName}
@COMMENTS {CommentText}


Figure 1. Topological representation of a revolute joint
with associated relative rotation element.
  1. A relative rotation joint is a constraint element that allows the definition of the relative rotation, Φ, of a master joint that can be a cylindrical joint, a planar joint, a revolute joint, or a universal joint. The master joint must define this relative rotation through the optional @RELATIVE_ROTATION_NAME keyword.
  2. The relative rotation joint is associated with an edge, EdgeName. Vertices Vertex0Name and Vertex1Name are associated with this edge. A positive relative rotation is obtained when the body connected to Vertex1 rotates with respect to the body connected to Vertex0 about the axis of the joint according to the right hand rule. Find more information about: the representation of multibody systems, and the formulation of constraints in multibody systems.
  3. Figure 1 illustrates the connection between the master joint and its relative rotation joint. In this case, the master joint is a revolute joint with associated edge EdgeRvj, whereas the edge associated with the relative rotation element is denoted EdgeRvr. Note that edges EdgeRvj and EdgeRvr must share their vertex v0, labeled VertexB1. The relative rotation, Φ, is a degree of freedom associated with vertex v1 of the relative rotation joint, labeled VertexB3.
  4. Optionally, a torsional elastomeric damper, EldModlName, can be added to the joint. An torsional elastomeric damper is a force element that generates a moment Med = Med (Φ, dΦ/dt); it consists of elastic branches, dashpot branches, viscous branches, and plastic branches.
  5. Optionally, a backlash model, BklModlName, can be specified for the revolute joint relative rotation. The backlash model limits the range of values for the relative rotation, Φ.
  6. Optionally, a friction model, FctModlName, can be specified for the revolute joint relative rotation. The friction model applies a friction torque based on a friction law.
  7. It is possible to attach comments to the definition of the object; these comments have no effect on its definition.


Sensors can be defined to extract information about relative rotations. The following SensorType and associated FrameName specifications are allowed for relative rotations: RELATIVE_ROTATIONS.

No u value or v value are accepted for relative rotations.