New performance indices for 6-dof UPS and 3-dof RPR parallel manipulators

In this paper we introduce two new posture-dependent performance indices for 6-dof UPS and 3-dof RPR parallel manipulators. One is based on an object-oriented metric in the workspace (end-effector dependent) and the other one takes the angular velocities of the passive joints into consideration (end-effector independent). Both newly defined indices are invariant under rigid-body motions and similarities, they have a geometric meaning, and they can be computed in real time. Moreover these indices can also be used for robot design, especially the end-effector independent index is suited for that problem by taking the geometry of the manipulator into consideration. We also optimize the design of 6-dof UPS and 3-dof RPR parallel manipulators with respect to both newly presented indices.