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A SIMPLE CONTROL METHOD COPING WITH A KINEMATICALLY ILL‐POSED INVERSE PROBLEM OF REDUNDANT ROBOTS: ANALYSIS IN CASE OF A HANDWRITING ROBOT
Author(s) -
Arimoto Suguru,
Hashiguchi Hiroe,
Ozawa Ryuta
Publication year - 2005
Publication title -
asian journal of control
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.769
H-Index - 53
eISSN - 1934-6093
pISSN - 1561-8625
DOI - 10.1111/j.1934-6093.2005.tb00380.x
Subject(s) - robot , inverse kinematics , redundancy (engineering) , control theory (sociology) , computer science , kinematics , handwriting , artificial intelligence , control (management) , physics , classical mechanics , operating system
In order to enhance dexterity in execution of robot tasks, a redundant number of degrees‐of‐freedom (DOF) is adopted for design of robotic mechanisms like manipulators and multi‐fingered hands. Associated with such DOF redundancy relative to the number of physical variables necessary and sufficient for description of a given task, an extra performance index is introduced for controlling such a redundant robot in order to avoid arising of an ill‐posed problem of inverse kinematics from the task space to the joint space. This paper treats a handwriting robot as an illustrative example and shows that such an ill‐posedness of DOF redundancy can be resolved in a natural way by using a novel concept named “stability on a manifold”. It is shown theoretically that sensory feedback signals with a simpler form computed on the basis of measurement data of task‐description variables render the closed‐loop dynamics to converge asymptotically to a target task‐description lying on a lower‐dimensional manifold of steady states. Computer simulation concerning specified robot tasks verifies the effectiveness of the proposed control scheme, which results in human‐like distribution of joint motions.