POSTURE MEASURE AND CONTROL FOR ROBOT COMPLIANCE TASKS

Various measures have been proposed for evaluating the compatibility o f manipulator postures with respect to task requirements from kinemati c and dynamic standpoints. In most previous studies, the measures were used to determine optimal postures for manipulators in advance, and t heir effects on system performance were generally examined statically. When posture measures are applied to controlled dynamic systems, howe ver, their effects are usually not evident, because deficiencies (meri ts) caused by bad (good) postures can be compensated for by the contro ller. On the other hand, postures determined according to proper measu res can still alleviate the controller's load and be helpful in contro l strategy realization. In this paper, we propose that planned complia nt motion trajectories should be accompanied by proper postures for co mpliance tasks. Thus, we analyze manipulator dynamic behavior by using postures specified according to various measures. And, because differ ent postures are used in different phases of the compliance task, a po sture selection and control scheme is also proposed to govern the sequ ence of postures selected according to task requirements and environme nts. Redundant robot manipulators were used for investigation because of their better manipulability. Simulations that demonstrate the effec tiveness of the proposed scheme are described, (C) 1998 John Wiley & S ons, Inc.