Type Synthesis of a Family of 3-DOF Spherical Parallel Mechanisms Using Upper-Lower Combination and Axis Movement Theorem

摘要

Spherical parallel manipulators (SPMs) have a wide range of applications such as orienting devices and robotic wrists. In this paper, the 3 independent rotational characteristics of SPMs are divided into two groups orienting from the upper and lower parts of the SPMs respectively. The type synthesis of such SPMs is performed by using upper-lower combination rules and the axis movement theorem. The concept of parallel mechanism with symmetrical characteristics is introduced. Then, some novel SPMs with symmetrical characteristics are represented by introducing the PR joint and the composite joints deduced from the simple joints. Finally, the different geometrical conditions of assembly for parallel manipulators (PMs) with different characteristics are discussed. The concept of the upper-lower combination may provide a new idea for type synthesis of parallel mechanisms.