Operational quality analysis of parallel manipulators with actuation redundancy

This paper presents the analysis of the operational quality of redundantly actuated parallel manipulators. Two types of the actuation redundancy of a parallel manipulator are considered, which are introduced by replacing passive joints with active ones and by adding limbs. The operational quality of a parallel manipulator with/without actuation redundancy is quantified in terms of force applicability and operational stiffness. The effects of the two types of the actuation redundancy on the operational quality of a parallel manipulator are analyzed and compared. Both types of the actuation redundancy are shown to improve the operational stiffness as well as the force applicability, but in quite different ways. With such differences fully understood, it is possible to best utilize the actuation redundancy for a parallel manipulator with high force applicability and high operational stiffness