A new index for the performance evaluation of parallel manipulators: A study on planar parallel manipulators

This paper addresses the issue of performance evaluation of parallel manipulators. In the analysis and design process of parallel manipulators, the performance evaluation is the most important problem. The developed index will be fundamentally involved in the process, especially in that of optimum design. Although parallel manipulators have been extensively studied for more than twenty years, unfortunately, the concepts of manipulability and condition number, which are used extensively in the analysis and design of parallel manipulators, were, in general, directly transposed from serial robots from the very beginning. Recently, both theoretical analysis and experiences indicate that these concepts, especially the local conditioning index (LCI), seem defective when they are applied in parallel manipulators. This paper introduces a new index for parallel manipulators. This study will first investigate the application of the new index in parallel manipulators with a planar structure. The proposed concept shall be said to be extended to other parallel manipulators.