Modeling of Synthetic Fiber Ropes and Frequency Response of Long-Distance Cable–Pulley System

Abstract

In recent years, synthetic fiber ropes have attracted much attention because of their potential to increase the load capacity, reduce the size, and lighten the weight of tendondriven mechanisms. However, the mechanical characteristics of synthetic fiber ropes in a dynamic loading situation remain an open problem because of their visco-elasto-plasticity. This paper focuses on modeling synthetic fiber ropes, and the frequency response of a long-distance cable-pulley system for a tendondriven robot. We show that a synthetic fiber rope can be modeled by Flory's model, and that it can be reduced to a conventional four-element model with sufficient preloading. After empirically acquiring the parameters of the four-element model for four different synthetic fiber ropes, each frequency response of a longdistance cable-pulley servo system was measured and compared to the analytical results based on the model, as well as the results of a stainless wire rope. Consequently, we show that synthetic fiber ropes achieved comparable bandwidth to that of the stainless wire rope. The damping of synthetic fiber ropes was found to suppress the servo system gain. This is useful for joint control of a tendon-driven robot with a relatively large amount of inertia, such as a long-reach robot arm.

Empirical Study for 3D-Printed Robot Design: Dimensional Accuracy of a Hole and Proposal of a New Shaft-Fastening Method

“…On the other hand, the tension increased immediately after the current command value was changed and then decreased gradually. This is considered to result from the viscoelasticity of the synthetic fiber rope, as shown in the literature [22]. The above demonstrates that this method is very effective for mounting press-fit parts on robots made by 3D printers.…”

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

“…We selected a 2 mm-diameter Dyneema rope (tensile strength of 4.29 kN, DB-96HSL, Hayami industry) as the JCTs because of these characteristics. We intensively investigated the basic mechanical properties of various types of synthetic fiber ropes in our previous work [15] [16] [17], and found that Dyneema had the highest durability against sharp repetitive bending.…”

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].…”