Seamlessly wound multi-level cable drive system for high reduction gear ratio

Abstract

In this paper, cable drive mechanism is proposed to implement high reduction gear ratio. Although cable drive mechanism has great advantages such as light weight, zero backlashes and high degree of freedom in terms of mechanical design, it is restrictively utilized for the robotic applications because it is hard to implement high reduction gear ratio over 10 to 1. This is due to the complexity of tension adjustment units which should be installed at every reduction level for the conventional mechanism. Therefore mechanical structure becomes rather bulky and heavy to mount in the robotic joint. Proposed mechanism implements multi-level reductions by adopting seamless winding method which links the previous output axis to the next input axis. This enables high reduction with only one single wire cable. Consequently, it is possible to reduce the mechanical complexity significantly. Based on the proposed method, 3D CAD design was provided and prototype was manufactured. Moreover, experiments were carried out and the results were analyzed.