Development of New Terminal Fixation Method for Synthetic Fiber Ropes

Abstract

A synthetic fiber rope is potentially capable of replacing a stainless steel wire rope because it is light weight, and has high tensile strength and flexibility. In order to exploit the maximum tensile strength of the rope, a terminal fixation method with a sufficient fixing force is essential. However, this is extremely difficult in the case of synthetic fiber ropes due to their small friction coefficients. This paper proposes a new terminal fixation method combined with a grooved pulley and pin. The grooved pulley is utilized in order to increase the friction between the synthetic fiber rope and the pulley, and the rope is wound around the grooved pulley. The extremity of the rope is fixed at a pin by hanging a loop with a figure-eight knot. The appropriate groove shape is found experimentally and it is confirmed that our method achieves maximum fixation force of 91.3% against the rope breaking force. We provide implementations examples for a long-reach tendon-driven manipulator.

Repetitive Twisting Durability of Synthetic Fiber Ropes

“…The rope is wound around the fixed pulley several times so that the tension is sufficiently damped at the end as per Euler s belt theory. Then, a loop is formed at the end of the wrapped rope by tying a double figure-eight knot; the loop is fixed by hanging it on a pin [18]. The tensile strength is measured when the rope breaks in the straight section between the jigs.…”

Super Dragon: A 10-m-Long-Coupled Tendon-Driven Articulated Manipulator

“…However, fixing the Dyneema rope to the drive pulley is very difficult because of the low friction coefficient. Therefore, we developed a new terminal fixation method using a grooved pulley and a figure-eight knot hanging on a pin [18] shown in Fig. 8.…”

“…Arrangement of tendons: (a) coupled tendon-driven mechanism and (b) weight compensation mechanism[18].…”

Bundled Wire Drive: Proposal and Feasibility Study of a Novel Tendon-Driven Mechanism Using Synthetic Fiber Ropes

“…Thus, if we were to fully exploit these advantages of synthetic fiber ropes, it may be possible to develop a high performance robot, which is not feasible with conventional mechanisms. In our previous works, we investigated modeling of synthetic fiber ropes [3], tensile strength degradation by bending [4], repetitive bending durability [5], and the terminal fixation method [6].…”