A Three-Actuator Cable-Driven Parallel Robot with a Rectangular Workspace

In the realm of cable-driven parallel robots (CDPRs), the conventional notion entails that each cable is directly actuated by a corresponding actuator, implying a direct relationship between the number of cables and actuators. However, this paper introduces a paradigm shift by contending that the number of cables should be contingent upon the desired workspace, while the number of actuators should align with the robot's degrees of freedom (DoF). This novel perspective leads to an unconventional design methodology for CDPRs. Instead of commencing with the number of actuators and cables in mind, we propose an approach that begins with defining the required workspace shape and determines the requisite number of cables. Subsequently, an actuation scheme is established where each actuator can drive multiple cables. This process entails the formulation of a transmission matrix that captures the interplay between actuators and cables, followed by the mechanical implementation of the corresponding cable-pulley routing. To illustrate this approach, we provide an example involving a 2-DoF CDPR aimed at covering a rectangular workspace. Notably, the resulting Wrench-Closure Workspace (WCW) and Wrench-Feasible Workspace (WFW) of the proposed designs exhibit favorable comparisons to existing CDPRs with more actuators.