Abstract

A spatial 3 degrees-of-freedom mechanism employing Stewart Platform structure is proposed: the mechanism maintains the 3 - RRPS structure of Stewart Platform but has an additional passive PRR serial sub-chain at the center area of the mechanism in order to constrain the output motion of the mechanism within the output motion space of the added P RR serial subchain. The forward and reverse position analyses of the mechanism are performed. Then the mechanism having both the forward and the reverse closed-form solutions is suggested and its closed form solutions are derived. It is confirmed, through the kinematic analysis of those two proposed mechanisms via kinematic isotropic index, that both the proposed mechanisms have fairly good kinematic characteristics compared to the existing spatial 3-DOF mechanisms in literature ^1.6.

• Keywords: Stewart Platform Mechanism(스튜워트 플랫폼 메커니즘),Parallel Mechanism(병렬 메커니즘),Closed- form Solution(해석해),Kinematic Analysis(기구학 해석),Kinematic Isotropic Index(기구학 등방성 지수)