Coordination of Motion in a Spacecraft/ Manipulator System

A control scheme for the coordination of motion in a space craft/manipulator system is presented. It is shown how end- effector motion can be decoupled from satellite motion, satellite rotation, or total system momentum by selecting suitable gen eralized speeds for the satellite. The schemes are based on recursive calculation of kinematics and dynamics, and 12 degrees of freedom can be controlled without excessive com putational effort. Feedback linearization and decoupling of end-effector motion and total system momentum are discussed in detail. The satellite controller can then be developed in dependently of the manipulator controller, and reaction jets and momentum wheels are used only to reposition the satel lite. The end effector can be controlled accurately with a high bandwidth, while a slow, gross positioning can be used for the satellite. The resulting controller is very efficient in terms of fuel. The spacecraft/manipulator system is regarded as a re dundant manipulator of the macro-micro type with 12 degrees of freedom, and a redundancy resolution scheme based on the augmented task space approach is used to generate the position and orientation reference for the spacecraft. The proposed con troller was simulated with a 12-degrees-of-freedom model that was generated with a recursive formulation of the Jacobians. The results are presented in this article.