Analysis of a High Stiffness Warehousing Cable-Based Robot

Abstract

This paper presents and analyzes a novel architecture for a fully constrained cable-based robot that is used in warehousing tasks. A mobile platform is connected to a static box by a set of twelve cables; the cables arrangement allows the mobile platform to achieve stiff positions with constant orientation along with large planar motions. The mechanical analysis of the robot includes inverse and forward kinematics, as well as static analysis and stiffness models. In addition, a workspace analysis describes the feasible boundaries for the suspended and fully constrained cases. Then, the stiffness attributes for both cases are analyzed and discussed. Simulation results show that the proposed robot meets the warehousing requirements of large workspace, high stiffness, and low force input.

Design of a Planar Cable-Driven Parallel Robot for Non-Contact Tasks

“…This expedient allows obtaining a translational motion of the EE without any external constraint, provided that all cables are taut. This is useful in the case of large-scale industrial tasks, such as pick-and-place and warehousing [23], or operations that need deployable systems, such as rescue and contour crafting [24,25].…”

“…In addition, the pulley swivel axes are equipped with rotary encoders to achieve redundant kinematic measures, and cable tensions are measured with shear beam load cells integrated into the proximal anchor systems. Like other planar CDPR that share the idea of parallelogram mechanisms [23,26], this system allows the platform to move on a defined plane, excluding low-amplitude oscillatory motions induced by external disturbances [27,28]. On the other hand, unlike the others, the proposed system shows three advantages: the use of a single cable loop, instead of two separate cables, ensures that the parallel cable segments are in tension when controlled by a single actuator, thus reducing the number of actuators to be used; the cable anchor system includes a measurement unit to continuously monitor cable tensions and cable angles with respect to the frame; the mounting arrangement of the swivel pulleys allows to estimate the cable lengths as distances between two precisely defined points, which are the intersections between the swivel axes and the work plane, without introducing geometrical approximations.…”