International Journal of Robotics Research vol:7 issue:4 pages:18-33
A control approach for the execution of robot tasks in contact with the environment is worked out. The input to the con troller consists of the task specification described in part I. The control approach is based on external force and tracking loops, which are closed around the robot positioning system. The position control loops tend to decouple and linearize the complex robot dynamics, and therefore they present to the external controllers a system which is easy to model and easy to control. Design and properties of external control loops are discussed in great detail. In particular, the role of a passive compliance with respect to task execution speed and distur bance rejection is analyzed both qualitatively and quantita tively. The resulting compliant motion controller has been tested experimentally, and proved to be very robust and to yield the theoretically expected performance.