Coordinated control of a satellite mounted robot arm and the satellite attitude - Results of the on-orbit experiments on NASDA's ETS-VII satellite

When a robot arm(s) moves on a satellite to conduct some tasks, it provides reaction torque to the satellite platform. However, satellite's attitude must be maintained against the reaction to maintain the communication link with a data relay satellite and to generate electrical power from its solar panel(s). National Space Development Agency of Japan (NASDA) launched a such satellite named ETS-VII which is shown in Fig.1 in 1997 to conduct the rendezvous docking and space robot technology experiments. The satellite has a 2m long robot arm and it handles payload weighing up to 400kg. Mass of the satellite is 2.5t and therefore, the reaction form the robot arm is not negligible. This paper introduces how the coordinated control of the satellite attitude and the onboard robot arm is realized.