Cable-Driven Parallel Mechanisms: Application to a Locomotion Interface

Abstract

Over the past decade, cable-driven parallel mechanisms have been used for several purposes. In this paper, a novel application is proposed, namely, using two 6DOF cable-driven parallel mechanisms sharing a common workspace to obtain the mechanical base for the design of a locomotion interface. The methodology used to develop the architecture of the mechanisms is presented, and the two main criteria used to optimize the geometry are described. These criteria are based on the wrench-closure workspace and a detection of the mechanical interferences between all the entities of the locomotion interface (cables and moving bodies). Then, the final design is described and its performances are given. Finally, in order to validate the relevance of the mechanism for the locomotion interface’s design, tensile forces in the cables are computed to observe the maximal values reached during a typical human gait trajectory.

Interference estimated time of arrival on a 6-DOF cable-driven haptic foot platform

“…Due to the geometry of cable-driven platforms described in [2] and the trajectories of the feet, cable interferences can occur. As interferences restrict the size of the workspace, various methods were previously devised to analyze them.…”

Cartesian Control of a Cable-Driven Haptic Mechanism

“…the overall dimension of the complete CDLI) so as to avoid cable interferences and to minimize human-cable interferences while the user is walking (Perreault & Gosselin, 2008). It must be noted that due to the unilaterality of the actuation principle, a cable-driven parallel platform needs at least seven cables in order to control a six DOF platform.…”

“…the wrench applied by the cables on that platform), τ i is the tension vector of the ith (of n) cable, W is the pose-dependent wrench matrix computed by the platform Jacobian matrix that links Cartesian to articular velocities, G is a weighting matrix with its diagonal elements such that g i = 1 for all i, where the mathematical derivation of (3) is presented in (Barrette & Gosselin, 2005) and an application is described in (Perreault & Gosselin, 2008).…”

“…CDLI employs two independent cable-driven haptic platforms constrained in six degrees of freedom (Perreault & Gosselin, 2008). Each platform is attached to a foot of the walker.…”

Human Safety Algorithms for a Parallel Cable-Driven Haptic Interface

“…A user can walk inside a virtual environment and interact with any objects in it, including the environment itself. Due to the geometry of cable-driven haptic platforms described in [13] and the trajectories of the feet, cable interference can occur, and the platform can leave its designated workspace. Furthermore, when in use, cables can snap, wind up incorrectly on their reels, or damage their tension sensors, all potentially leading to failure.…”