Optimal Manoeuvres for Space Manipulators Deployment

Abstract

High cost and risk related to manned space mission calls for the automation\nof in-orbit activities. Several tasks currently performed by\nastronauts could be indeed exploited by servicing orbiters, conceived\nas graspers with arm-like appendages. This paper aims to present the\nfirst findings of a research program recently started at the University of\nRome "La Sapienza", including theoretical, numerical and experimental\naspects. Dynamics of multibody systems obviously apply to this special\nkind of manipulators, which peculiar asset is their intended operations\nin a free, completely unrestrained configuration.\nThe study of the motion of a free-flying robot is rather more complex\nthan the study of a similar system working on the Earth. A coupling\nbetween attitude and orbital dynamics results, leading to special requirements\nof analysis and simulation of this complex system. Space\ngraspers need suitable laws for the guidance of the arms, in order to\n"capture" the to-be-repaired spacecraft and therefore perform the required\nfixes. Furthermore the attitude control of the in-orbit platform\nhas to be fulfilled, in order to compensate the attitude variation of the\ngrasper due to the manipulator motion. This paper presents the study\nof a 2D flexible manipulator. The dynamic equations are recalled. The\noptimization of both the guidance law for the arms and the attitude control\nof the platform is carried out, taking into account also the flexibility\nof the arms. Extensive numerical simulations are presented to validate\nthe approach.