Planar Cable-Driven Robots with Enhanced Orientability
Cable-driven robots consist of a moving platform to which cables are attached and pulled using ground-mounted motors. Even though there are many advantages of these over conventional robots, there is a serious limitation of restricted orientations of the platform. Furthermore, the orientation depends on the external load. In this work, the inherent limited orientation attribute of planar cable robots is demonstrated with analysis and simulations. Also presented is a concept and implementation of complete orientability of the end-effector attached to the moving platform of a planar cable-driven robot by using only one additional cable. The new concept, by design, gives rise to a moment load on the moving platform, which does not yet appear to have been considered in cable-driven robots. Implications in this analysis and path planning are discussed. Working prototype of a planar three-cable robot with an extra cable to enhance the orientability was built and tested. Additionally, for a given configuration and loading, cable tensions were pre-calculated and stored in a structured database for expeditious execution of the path and orientation of the robot.
KeywordsPlanar cable-driven robot orientations
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