ABSTRACT
This chapter discusses some of the influential hypotheses on motor control, which has been proposed for the control of kinematically redundant limbs. The problem of inverse kinematics has been a major topic of research in various disciplines, such as motor control and robotics. In both disciplines a compromise has to be made between flexibility at the one hand, which requires multiple joints and muscles, and reducing the number of redundant degrees of freedom in order to obtain unique control properties at the other hand. For movements of a two-joint arm in a two-dimensional horizontal plane there is a unique one-to-one relation between changes in joint angles and changes in hand position. However, for a kinematically redundant arm any position of the hand can be achieved by a large number of arm postures. According to the traditional view of motor control, the central nervous system plans and executes movements in terms of biomechanical variables.
