Abstract: In order to develop new parallel mechanisms, a 6-DOF steel band parallel robot with kinemics chain composede of steel band having arc-shaped cross section is presented. The structure and principle of the steel band parallel robot are illustrated. Finite element analysis theories including static and buckling analysis, which are based on the variational principle, are used to determine the buckling equation which can compute the instability critical load. Different structural steel bands with cross sections from arc to straight line are analyzed by using FE software ANSYS, and relationships between structural parameters and the instability critical load are obtained. The simulation results are evaluated by experiments. Instability property analysis of steel-band parallel robot as a whole is analyzed systematically at different postures of translation motion, and the relationships between posture parameters and instability critical force are obtained. The results show that steel band with cross sections from arc to straight line can receive certain pressure, the instability critical force increases in direct ratio to the magnitude of central angle or thickness, but in inverse ratio to the length of steel band. For ascending motion of mobile platform, the instability critical force reaches maximum at the altitude of 500 mm which can be specified as the optimal posture. For mobile platform translating along Y axis or the path with =60 at the same altitude, when 100 mm200 mm, the instability critical forces are relatively great. For mobile platform along the path of =500 mm with 1050 at the same altitude, the instability critical forces are also relatively great. These results can be used to optimize structural design and determine the stiffness working space of a steel band parallel robot.

Key words: Arc-shaped cross section, Finite element analysis, Instability characteristics, Steel band parallel robot