ABSTRACT
This chapter addresses the problems involved in the seemingly simple task of moving a set of linked segments from one position to another. Often, there are fundamental features of a task that are difficult to describe in either extrinsic or intrinsic frames. Certain kinematic features of real movements are simpler to describe in extrinsic rather than intrinsic coordinates. A good deal of information is available about the kinematics of human movements, which should exert a selection pressure on hypotheses, but this does not always happen. Bullock and S. Grossberg attempt to account for some of the kinematic details in a model called "Vector Integration To Endpoint". In robotics, Problem III usually does not arise, since motors can be situated in one-to-one correspondence with the kinematic degrees of freedom, and the mechanical properties of the motors do not vary. The cognizance taken muscle properties and of reflex effects makes the equilibrium-point idea more physiological than the stepper-motor-oriented schemes from robotics.
