ETS-VII Flight Experiments for Space Robot Dynamics and Control - Theories an Laboratory Test Beds Ten Years Ago, Now in Orbit

The Engineering Test Satellite VII (ETS-VII), an unmanned spacecraft equipped with a 2-m long, six-degree-of-freedom manipulator arm, was developed and launched by the National Space Development Agency of Japan (NASDA). ETS-VII has successfully carried out a variety of on-board experiments with its manipulator arm, and these key technologies are essential for an orbital free-flying robot. These results will provide a solid basis for future satellite servicing missions. This paper highlights manipulator control utilizing the concepts of the generalized Jacobian matrix and the reaction nullspace. These concepts have been proposed and discussed for the past ten years using laboratory test beds, and their practical application has now been demonstrated in orbit. KEY WORDS—space manipulator, reaction dynamics, satellite servicing