Cable Routing Design and Performance Evaluation for Multi-Link Cable-Driven Robots With Minimal Number of Actuating Cables

A multi-link cable-driven robot (MCDR) usually has a large number of redundant actuating cables due to its modular cable routing scheme. To reduce the number of actuating cables while keeping the advantages of the modular MCDRs, a hybrid modular cable routing method is proposed, in which some actuating cables are co-shared by adjacent cable-driven joints. Consequently, the total number of actuating cables can be reduced to n + 1 for an n-degree-of-freedom (n-DOF) MCDR. Focusing on MCDRs composed of identical 2-DOF cable-driven universal joint modules, the performance of the MCDR with the hybrid modular cable routing scheme is evaluated. It is concluded that: 1) the wrench-closure workspace of an MCDR with the hybrid modular cable routing scheme remains unchanged compared to the conventional modular cable routing scheme; 2) the maximal joint speed is inversely proportional to the total number of joint modules that co-share one actuating cable; and 3) the loading capability of an MCDR is a monotone decreasing function of the number of co-shared actuating cables. To verify the conclusions obtained, computer simulations are conducted on an MCDR with different cable routing schemes. Besides, the hybrid modular cable routing with alternatively co-shared actuating cables is an ideal cable routing scheme as it has the minimum loss of performance on motion speed and loading capability.