On the non-linear dynamics of a space platform based mobile flexible manipulator

Abstract

This paper aims at development of a rather versatile tool for studying the dynamics and control of an orbiting flexible manipulator. It is motivated by the Canadian contribution, in the form of the mobile servicing system (MSS), to the U.S. led Space Station program, scheduled to be operational by the turn of the century. To begin with, a relatively general dynamical formulation is developed for a large class of systems characterized by interconnected beam and/or rigid articulating members forming a chain-type geometry. As can be expected, the governing non-linear, non-autonomous and coupled equations of motion, extremely long even in matrix notation, are not amenable to any known closed form solution. Hence attention is focused towards development of an efficient numerical code, in a modular format, to help assess the relative importance of the various system parameters. Validity of the formulation and the computer code are assessed and their operational aspects demonstrated through a parametric response analysis. Emphasis throughout is on methodology and general approach leading to understanding of the multibody dynamics problem at the fundamental level. The versatility of the formulation and corresponding code permits dynamical analysis and non-linear control of a wide class of space- and ground-based manipulators. Results suggest that interaction between the Space Station and MSS can lead to undesirable librational and vibrational response for the station. The station response, in turn, may diminish performance of the highly flexible manipulator system. The versatility of the formulation is demonstrated in its application to several other configurations: scientific and communications satellites with flexible beam-type members as well as tethered systems.