A novel design for fully constrained planar Cable-Driven Parallel Robots to increase their wrench-feasible workspace

Cable-Driven Parallel Robots (CDPRs) are a special kind of parallel manipulators that offer several advantages compared to the conventional rigid parallel robots. One of the most interesting advantages is their ability to cover large working areas since long cables can be easily coiled. The practical limitation on the permissible cable tensions, however, causes a considerable decrease in the size of the wrench-feasible workspace (WFW) of these robots. To solve this problem in the case of fully-constrained planar CDPR with 3 degrees-of-freedom, this work proposes a novel design, based on the addition of passive carriages to the robot frame. It allows to significantly reduce the variation in the cables direction and therefore in the cable forces, resulting in a notable increase in the size of the WFW. This work presents the kinematic and static models of the new robot and proposes a preliminary approach for the resolution of the static equilibrium. The WFW of the new robot is investigated in different situations and compared to that of a conventional planar CDPR, showing a significant improvement in every case studied.