A dexterity comparison for 3-DOF planar parallel manipulators with two kinematic chains using genetic algorithms

In this research work, a dexterity comparison is performed for seven three-degree-of-freedom (3-DOF) Planar Parallel Manipulators with two kinematic chains (PPM2KCs) using genetic algorithms. Introducing a new design approach, one of the three kinematic chains of seven possible fully planar parallel manipulators (FPPMs) is disconnected in order to design the new seven PPM2KCs, and one active actuator is added to the first leg to maintain the 3-DOF. These manipulators are designed on the basis of two purposes: (i) increasing the workspace area, and (ii) reducing the chance of interference since the three independent kinematic chains not only cause interference among the mechanical components but also reduce the workspace, which are the major challenges for parallel manipulators. Afterwards base distances are optimized using genetic algorithms (GAs) to compute the performance indices kappa and GDI for the PPM2KCs. The results have been examined regarding especially two objectives: (i) selecting the best possible architecture among the seven new designed configurations for a specific task, and (ii) analyzing the correlation between joint types (prismatic or revalue) and dexterous maneuverability for PPM2KCs. It has been concluded that the PPR (prismatic-prismatic-revolute) planar parallel manipulator is the best configuration, providing the best dexterous maneuverability among the others. (C) 2009 Elsevier Ltd. All rights reserved.