Dynamic balancing of two planar parallel 3-DOF mechanisms without counter-rotations

This article deals with dynamic balancing of two planar parallel 3-DOF mechanisms, namely 3-PRR and 3-RPR. The goal of this paper consists in cancellation of forces and moments transmitted from the end-effector to the base. Several approaches have been used to compensate the shaking forces and shaking moments of parallel mechanisms, but in all of them, using counter rotations was essential, especially when the mechanism consists of prismatic pair. In order to eliminate the counter rotation, dynamic balanced four-bar mechanisms are used. Symmetric mechanisms are used to achieve dynamic balanced situation. This solution is used for presenting manipulators with prismatic pairs. Numerical simulations are carried out using Adams software and the results reveal that no force or moment is applied to the base.