Workspace Analysis of Redundant Cable-Suspended Parallel Robots

This paper focuses on cable-suspended parallel robots (CSPRs), a subclass of cable-driven parallel robots, and particularly on the analysis of their workspace. CSPRs present, among other interesting characteristics, large workspaces and high reconfigurability, which make them attractive for a large variety of applications, especially for pick and place operations over wide spaces. This paper is based on the assumption that the safest (and cheapest) control scheme for a redundant CSPR consists, at the current state of development, in actuating only 6 cables at a time. This paper shows how, under this assumption, it is still possible to take advantage of redundancy to enhance the workspace and eventually reduce the maximal tension among cables. A simple interval-analysis routine is presented as a tool for the workspace and trajectory analysis of a redundant CSPR, and the results of a case study on an existing prototype are discussed.