Anthropomorphic robotics. II. Analysis of manipulator dynamics and the output motor impedance.

An important factor in trying to capture the complexity of many manipulation problems is the notion of Output Motor Impedance, i.e., the relationship between a set of disturbing forces and the resulting variation in arm configuration. The functional significance of such force/displacement characteristics is investigated, showing how several aspects of different manipulation tasks (holding against gravity, inserting, fast moving, and throwing) can be naturally described in terms of appropriate modulation of the impedance characteristics of the manipulator. For this reason, impedance modulation can be considered an integral part of motor control.