In this book, motion control design for functionally related systems has been discussed. Functionally related systems are systems ‘virtually’ interconnected through certain functional relations defined by a task that the systems need to execute in a cooperative manner, even though they may be physically separated. The functional relations, which can be expressed as functions of the coordinates of the systems, form a system of ‘virtually’ interconnected subsystems. Each of these functions represents a functional dependence between the coordinates of the overall system, i.e., coordinates of its subsystems. The method for the task control presented in this book relies on enforcing the functions to track their references.