On the Relation of a Hand Trajectory of a Space Robot and Its Attitude Variation

Abstract

The subject of this paper is a space robot that has a manipulator arm mounted on a satellite body. As the attitude of the space robot is varied due to the arm motion, it is necessary to understand the relation of the arm trajectory and the attitude variation. In this paper, we evaluate the attitude variation and obtain the hand trajectory to minimize it for the simple case where the arm mass is concentrated on the hand. We study here two coordinate frames of the hand: an inertial frame and a satellite-fixed frame. For the inertial frame, the attitude variation is proportional to the area bounded by the hand trajectory and the origin. For the satellite-fixed frame, after the coordinate frame is transformed, the attitude variation is also proportional to the area bounded by the hand trajectory and the origin. In both cases, the hand trajectory to minimize the attitude variation is approximated by a hyperbola. Numerical simulation is executed to examine these results.