S.M.K Akhlaghi - Mechanical Engineering Department, Babol University of Technology, Mazandaran
Mojtaba Monjezi - Mechanical Engineering Department, Islamic Azad University, Susangerd Branch, Susangerd
Mehdi Monjezi - Mechanical Engineering Department, Islamic Azad University, E-Campus, Tehran

In this paper, the optimal designs of three planar 3-DOF parallel manipulators with 4-RPR, 3-RPR and 2-RPR structures are compared. The optimization of themanipulators are performed based on dexterity index, subject to constant orientation workspace. The optimizations are performed using particle swarmoptimizer with Semi-active congregation which improves the performance of PSO with passive congregation. Finally, it is shown that the 4-RPRparallel manipulator has a better performance than 2- RPR and 3-RPR manipulators according to the dexterityindex

Manipulator, dexterity,optimization, semiactive congregation