Structure Comparison and Optimal Design of 6-RUS Parallel Manipulator Based on Kinematic and Dynamic Performances

The effects of distinctive parameters such as revolute joint angle or spherical joint location of mobile platform in a 6-DOF 6-RUS parallel manipulators on workspace, kinematic, and dynamic indices are investigated in this study to select proper structure commensurate with performance. Intelligent multi-objective optimization method is used to design the manipulator. Considering distinctive parameters, relevant relations for developing inverse kinematic and Jacobin matrix are obtained. In order to study dynamic properties, mass matrix is obtained from calculating the total kinetic energy of the manipulator. After modifying multi-objective Bees algorithm, it used to optimize the manipulator structure considering all geometrical parameters with proper constraints. In addition of comparison of three well known 6-RUS manipulators' types, variation diagram of workspace, local and global dynamics and kinematics performance indices have been drawn with respect to structural parameters variation and limitation of these parameters with proper value are determined. Moreover, considering all dimensional parameters, Pareto front line of multi objective optimization of structure is presented based on dynamic and kinematic performance in pre-determined workspace. Based on the results, a fairly comparison among various types of 6-RUS manipulators can be conducted and the most appropriate set of dimensional parameters are selected based on specific demand.