On singularity avoidance and workspace enlargement of planar parallel manipulators using kinematic redundancy

The present paper applies kinematic redundancy to a 3 (R) under bar RR planar parallel manipulator in order to reduce the effect of singularity loci within the workspace. The proposed approach consists of an additional prismatic actuator at the base allowing a selective reconfiguration. The relationship between the redundancy and the effective workspace is studied by introducing a performance index called operational effectiveness. It is demonstrated that the proposed simple-redundant scheme is able to outperform more complex approaches in the sense of singularity avoidance and operational effectiveness improvement.