Quaternion-based kinematic control of redundant spacecraft/manipulator systems

This paper addresses kinematic control of a redundant space manipulator mounted on a free-floating spacecraft. Redundancy of the system with respect to the number of task variables for spacecraft attitude and manipulator end-effector pose is considered. Also, the problem of both spacecraft attitude and end-effector orientation representation is tackled. A nonminimal singularity-free representation of rigid body orientation is adopted: the unit quaternion; this allows avoiding representation singularities and formulating the inverse kinematics algorithms in terms of geometrically meaningful variables. Depending on the nature of the task for the spacecraft/manipulator system, a number of closed-loop inverse kinematics algorithms are proposed. Case studies are developed for a system of a spacecraft with a six-joint manipulator attached.