Analytical and experimental investigations of friction between synthetic fiber ropes and grooved pulleys

Abstract

Ropes made of ultrahigh molecular weight polyethylene fibers (one of synthetic fibers) are used for tendon driven robots because the synthetic fibers have both high strength and flexibility. In general tendon driven robots, the rope is wound around a grooved pulley. Although tension is applied to the rope by frictional force on the groove surface, the relation between the groove shape and the frictional force for the synthetic fibers is unknown. Since the rope is made of a lot of fibers, it requires a huge calculation cost to finely model and analyze the fiber. In this study, we propose a method to analyze frictional force between rope and pulley. We treat the rope as a homogeneous elastic body to reduce the calculation cost. By comparing with experimental results, we examined the effectiveness of the method. The tendency of analytical results agreed with experimental results.