Modeling and analysis of cable vibrations for a cable-driven parallel robot

In this paper we study if approximated linear models are accurate enough to predict the vibrations of a cable of a Cable-Driven Parallel Robot (CDPR) for different pretension levels. In two experiments we investigated the damping of a thick steel cable from the Cablerobot simulator [1] and measured the motion of the cable when a sinusoidal force is applied at one end of the cable. Using this setup and power spectral density analysis we measured the natural frequencies of the cable and compared these results to the frequencies predicted by two linear models: i) the linearization of partial differential equations of motion for a distributed cable, and ii) the discretization of the cable using a finite elements model. This comparison provides remarkable insights into the limits of approximated linear models as well as important properties of vibrating cables used in CDPR.