A Cable Based Active Variable Stiffness Module With Decoupled Tension

Abstract

Variable-stiffness modules add significant robustness to mechanical systems during forceful interactions with uncertain environments. Traditionally, most existing variable stiffness modules tend to be bulky by virtue of their use of solid components making them less suitable for mobile applications. In recent times, pretensioned cable-based modules have been proposed to reduce weight. While passive, these modules depend on significant internal tension to provide the desired stiffness and stiffness modulation capability tends to be limited. In this paper, we present design, analysis and testing of a cable based active variable stiffness module that can be realized to achieve a large stiffness range. Controlled changes in structural parameters (independent of cable length actuation) now permits independent modulation of the perceived stiffness with desired tension. This capability is now systematically evaluated on a hardware-in-the-loop experimental setup and results are analyzed.