The determination of workspace and the performance evaluation of PRoM-120 with 3 and 4 kinematic constants

This paper presented a parallel robotic manipulator having combined DOF, i.e., one translational and two rotational DOF, called PRoM-120. PRoM-120 is constructed by using 2PRU/PRS kinematic chains (KCs) and arranged in an asymmetric configuration. The objective of the research is to determine the workspace and to evaluate the performance of PRoM-120 for three cases based on the numerical values of its kinematic constants. The workspace is calculated by applying the discretization method. The inverse kinematic solution, direct singularity, inverse singularity, and actuators limit are taken as the significant factor to determine the workspace. Meanwhile, the performance of PRoM-120 is evaluated by applying conditioning index and transmission based index. It shows the conditioning index cannot be used for PRoM-120, or parallel manipulator having combined DOF. Assessing the performance of PRoM-120 using transmission based index exposes only less than 20% of the workspace be in the good transmission workspace. (paper)