Posture measure and control for robot compliance tasks

摘要

Various measures have been proposed for evaluating the compatibility of manipulator postures with respect to task requirements from kinematic and dynamic standpoints. In most previous studies, the measures were used to determine optimal postures for manipulators in advance, and their effects on system performance were generally examined statically. When posture measures are applied to controlled dynamic systems, however, their effects are usually not evident, because deficiencies (merits) caused by bad (good) postures can be compensated for by the controller. On the other hand, postures determined according to proper measures can still alleviate the controller's load and be helpful in control strategy realization. In this paper, we propose that planned compliant motion trajectories should be accompanied by proper postures for compliance tasks. Thus, we analyze manipulator dynamic behavior by using postures specified according to various measures. And, because different postures are used in different phases of the compliance task, a posture selection and control scheme is also proposed to govern the sequence of postures selected according to task requirements and environments. Redundant robot manipulators were used for investigation because of their better manipulability. Simulations that demonstrate the effectiveness of the proposed scheme are described. © 1998 John Wiley & Sons, Inc.