Minimum Cable Tensions for a Cable-based Parallel Robot with Application to Stability Analysis: A Descriptive Study

Abstract

Cable-based parallel robots are a special kind of parallel robots, where rigid links are replaced by cables. The robots show several promising advantages over their rigid-link counterparts. Using the cables with unilateral driving properties, however, introduces many new challenges, and one most critical challenge focused herein is the stability of the robot. The minimum cable tension distributions in the workspace for cable-based parallel robots are investigated in this research to determine the relationship between stability and minimum cable tensions. The wrench matrix is used to create the kinematic model of a cable-based parallel robot. Then, using convex optimization theory, a non-iterative polynomial-based optimization algorithm with the suitable optimal objective function is developed, in which the least cable tension at every position is determined. Furthermore, three performance indices are presented to depict the distributions of minimum cable tensions in a given workspace region. The three performance indicators can be used to assess the stability of cable-based parallel robots, which is crucial. A new workspace, the Preset Minimum Cable Tension Workspace (SMCTW), is also added, in which all minimum tensions exceed a given amount, achieving the specified stability criteria. Finally, to show the distributions of the minimum cable tensions in the workspace and the relationship between the three performance indices and the stability, a camera robot parallel driven by four cables for aerial panorama photography is chosen.