Résumé
This paper studies the shaking force balancing of a redundant planar 4-RRR parallel manipulator. Instead of considering the balancing of the parallel manipulator link-bylink or leg-by-leg, the architecture is considered altogether. To derive the complete manipulator force balance conditions, the linear momentum equations are obtained in which the loop equations are substituted. For both the force balance conditions with and without the loop equations, the resulting balance topologies are illustrated and discussed. By including the loop equations, linear relations between the motion of mechanism elements are included, which increases the balancing possibilities considerably. For specific kinematic arrangements additional linear relations between the motion of mechanism elements are obtained, resulting in simplified balance solutions. For this, symmetry is an important feature, for which redundancy can be an useful contribution.