Abstract
Future space missions are expected to use space robots that will support or replace astronauts to prevent them from having to carry out dangerous operations. One of the most important issues for such astronaut support robots is locomotion technology. Locomotion mechanisms require a long reach, lightweight materials, and robustness. JAXA has developed a novel locomotion system that has a long reach and is lightweight and robust. The system uses an extendable robot arm and several tethers. By controlling the length of the tethers, the robot can move within a triangular plane as defined by the anchor points of the tethers. The anchor point can be replaced by an extendable robot arm using a STEM (storable tubular extendible member) mechanism. The SRA (STEM robot arm) is lightweight and has a compact housing and long reach. However, it is also flexible, and this causes control difficulty. The REX-J [robot experiment on JEM (Japan experiment module)] demonstration mission was conducted at the International Space Station between August 2012 and May 2013. In the experiment, the vibrations of the SRA and tether system under various triggers were measured by a vision system. In this paper, the flexibility and vibration characteristics of the SRA of the REX-J robot in the space environment are analyzed based on the flight data, and their effects on the control of the robot and the utility of the system are evaluated.
