The Abaqus connector library is essentially a set of pre-packaged functions which mimic the behavior of various physical devices or components. Links, beams, actuators, hinges and universal joints are all available, as are more exotic and esoteric function such as flow-converters.
Control of these functions in a simulation adds what is effectively an MBD dimension to models, extending the scope and functionality of models; its even possible to incorporate control functions to complete the picture.