摘要 : Considering spatial parallel manipulators, volume and shape of the workspace are two important parameters for optimum design. In this paper, 6-DOF 3-RRRS parallel manipulators having symmetric link lengths are the subject of resea... 展开 Considering spatial parallel manipulators, volume and shape of the workspace are two important parameters for optimum design. In this paper, 6-DOF 3-RRRS parallel manipulators having symmetric link lengths are the subject of research. A novel geometric method is presented to classify all possible workspace shapes with variation of all the parameters of the manipulator. For each possible workspace shape, required geometric relationships between the parameters of the manipulators are established. In each case, the volume of the workspace is also determined in closed-form expression which is very helpful for optimum design since it makes determination of the workspace volume accurate and fast. With a case study, the usefulness of closed-form expression of the volume and characterization of the workspace based on geometric condition are verified, and optimal parallel manipulators free from voids and singularities are determined for a given workspace volume. 收起