TensionInitialisation

TensionInitialisation:
    .doc: """
Defines how the initial tension of the track is determined. Please note that
the final tension of the track is not only determined by these parameters and
the tensile stiffness of the track system. The tension also depends on the wheel
configuration and contacts with other components in the simulations such as the
terrain.
    tension_force    - If given this is the inital tension in the track, N
    rest_length      - If given this is the rest lenght of the track, meter.
                       The initial tension of the track is given from the final length of the track
                       when routed around all wheels. The tension is then the difference between
                       routed length and reste length times the tensile stiffness.
    node_distance    - If given this is the initla spacing between track nodes. The
                       spacing will give rise to a tension in the track that depends
                       on the tensile stiffness.

Note that if all three or two are given only one of them will be used to initialize
the tension in the track. The priority order is the same order as they are listed here,
tension_force, rest_length, node_distance.
"""

    optional tension_force is Real

    optional rest_length is Real

    optional node_distance is Real