On the Actuation Modes of a Multiloop Mechanism for Space Applications

Abstract

A symmetric, double-tripod multiloop mechanism (DTMLM), intended for grabbing objects in outerspace, is the subject of this article. Actuation modes are analyzed while introducing a novel tool applicable to space mechanisms. The key issue here lies in establishing the criteria for selecting the optimum mode from multiple actuation possibilities. The evaluation procedure includes generalized-force values, power requirement, and actuation-strategy models, along with their optimization. Accordingly, the optimization procedure targets the mode(s) with 1) uniformity of generalized-force distribution, 2) uniformity of power-requirement distribution, and 3) the fewest working actuators in a given maneuver. In this way, a rather complex problem is formulated in a simple manner, whereby the optimum actuation mode is found by listlookup, from a reduced number of candidates. The DTMLM, which carries three compound hinges plus three prismatic, and six revolute joints, has three degrees of freedom. To analyze the actuation modes of the mechanism, the dynamics model of the DTMLM is established; as well, five representative modes are selected from 84 possibilities. It turns out that the 3R-type (three revolute actuators) shows a uniform power-requirement distribution among the three actuators in the bending motion mode; in the 3P-type (three prismatic actuators), one single actuator is operational, and hence, takes all the load. Thus, the 3R-type is the best from the power-distribution viewpoint, thereby providing strong power support, but complex from the actuation-strategy viewpoint, as illustrated in the article. Simulation results and prototype experiments of the DTMLM are reported, thereby verifying the analysis results.

Novel Four-Cell Lenticular Honeycomb Deployable Boom with Enhanced Stiffness

“…In addition, an optimal design of lenticular booms has been developed for its modal and wrapping analysis [ 10 , 11 , 12 ]. Experiments and numerical studies of the flattening and wrapping processes of deployable composite thin-walled lenticular tubes have been conducted [ 13 , 14 , 15 , 16 , 17 ]. A TRAC boom has been designed using a data-driven computational framework without considering the influence of the bonding web between two tape-springs [ 18 , 19 ].…”