Sensitivity comparison of planar parallel manipulators

This paper deals with the sensitivity comparison of three Degree-of-Freedom planar parallel manipulators. First, a methodology is described to obtain the sensitivity coefficients of the pose of the moving platform of the manipulators to variations in their geometric parameters and actuated variables. Their sensitivity coefficients are derived and expressed algebraically for a matter of analysis simplicity. Moreover, two aggregate sensitivity indices are determined, the first one is related to the orientation of the moving platform of the manipulator and the other one to its position. Then, a methodology is proposed to compare planar parallel manipulators with regard to their workspace size and sensitivity. Finally, 3-RPR, 3-RPR, 3-RRR, 3-RRR and 3-PRR PPMs are compared in order to highlight the contributions of the paper.