Analysis on Kinematic Characteristics for a Spherical 3-DOF Parallel Mechanism with Constrained Stewart Platform Structure

스튜워트 플랫폼 구조를 이용한 구형 3-자유도 병렬 메커니즘의 기구학 특성 분석

In this work, a novel spherical 3-dof parallel mechanism is proposed and analyzed. The mechanism consists of three RRPS serial subchains and an additional passive 3-dof type serial subchain. Three RRPS serial subchains alone may form a structure of 6-DOF Stewart Platform mechanism. However, in the proposed mechanism, an additional passive serial subchain acts as constraints to restrict the output motion of the mechanism within 3-DOF spherical space. The closed form solutions of position analysis of the proposed mechanism and its first-order kinematic model are derived. Then its workspace size and kinematic characteristics are examined via kinematic isotropic index.