Torque Transmission Analysis and Design of a 3-DOF Spherical Parallel Manipulator

Static analysis plays an important role on the design and applications of manipulator. In this paper, The torque balance equations of the spherical 3-DOF manipulator was derived in closed forms by analyzing the relationship of its input and output torques, then the torque transmission evaluation index and the global torque transmission evaluation index were defined based on the torque balance equation and discussed in detail, at last, by using the physical model technique, the parameters of the spherical 3-DOF manipulator were optimized based upon the global torque transmission evaluation index. Moreover, an integrated design scheme of the spherical 3-DOF manipulator was confirmed when satisfied the assembly conditions, which can provide theoretical base for the applications of the spherical 3-DOF manipulator. The spherical 3-DOF manipulator can be used as the waist, wrist and the ultra-precision machine in which the requirements for high stiffness, high accuracy and good technological efficiency.